IPAC2018 - List of Keywords (lattice)

Paper	Title	Other Keywords	Page
MOZGBF5	Analysis of Polarization Decay at RHIC Store	polarization, resonance, emittance, target	76
	H. Huang, P. Adams, E.C. Aschenauer, A. Poblaguev, W.B. Schmidke BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. There are polarization losses in RHIC store due to various sources, such as emittance growth and higher order spin resonances. The beam polarization was measured several times over a store by the p-carbon polarimeters situated in both rings. These provide information on the polarization decay over time and also polarization profile development over time. A polarized jet was also used to monitor the polarization continuously through store, though with limited statistical accuracy. These polarization measurements and emittance measurements from the IPM are analyzed and the polarization loss from different sources are reviewed.
	Slides MOZGBF5 [4.526 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBF5
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MOPMF014	Polarization at eRHIC Electron Storage Ring, an Ergodic Approach	polarization, electron, simulation, storage-ring	112
	F. Méot BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Based on considerations of ergodicity of the dynamical system of an electron bunch at equilibrium, the preservation of polarization in an electron storage ring is estimated from the tracking of a very limited number of electrons. This has a substantial impact on required High Power Computing resources, in noticeable contrast with the method generally used that tracks tens of electron bunches, each comprised of thousands of particles, for several thousands of turns. It is also shown that a minimum number of tracking turns is required in order to ensure the numerical convergence of the linear regressions that yield depolarizing time constant values from tracking, in both methods.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF014
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MOPMF016	Progress on RCS eRHIC Injector Design	resonance, polarization, emittance, detector	115
	V.H. Ranjbar, M. Blaskiewicz, J.M. Brennan, S.J. Brooks, D.M. Gassner, H.-C. Hseuh, I. Marneris, F. Méot, M.G. Minty, C. Montag, V. Ptitsyn, K.S. Smith, S. Tepikian, F.J. Willeke, H. Witte, B. P. Xiao, A. Zaltsman BNL, Upton, Long Island, New York, USA I.V. Pogorelov Tech-X, Boulder, Colorado, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. We have refined the design for the Rapid Cycling Synchrotron (RCS) polarized electron injector for eRHIC. The newer design includes bypasses for the eRHIC detectors and definition of the lattice layout in the existing RHIC tunnel. Additionally, we provide more details on the RF, alignment and orbit control, and magnet specifications.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF016
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MOPMF021	Ground Motion Measurement and Analysis for HEPS	ground-motion, site, emittance, ion-source	125
	F. Yan, Z. Duan, D. Ji, Y. Jiao, Z.Z. Wang, Y. Wei, G. Xu IHEP, Beijing, People's Republic of China
	HEPS have very challenging beam stability require-ments. Special cares are mandatory in developing site vibration specifications, stable building design concepts, and passive and active ways to minimize effects on the stability of the photon beam and critical accelerator and beamline components caused by ambient ground motion sources. However, among all these work, reasonable as-sessment of the vibration induced beam instability has to be the first step. This paper will focuses on the measure-ment results of the ground motion on HEPS site, the es-tablishment of reasonable beam dynamic models, the influences of ground motion to the beam of main ring.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF021
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MOPMF028	A Superconvergent Algorithm for Invariant Spin Field Stroboscopic Calculations	simulation, resonance, polarization, storage-ring	145
	D. Sagan Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: National Science Foundation and the Department of Energy Stroboscopic averaging can be used to calculate the invariant spin field \bfn for particles with a finite oscillation amplitude in phase space. The standard technique starts with making a guess for \bfn(\bfr), which is a function of the phase space position \bfr. By tracking a particle's orbital position forward in time and then projecting the guessed \bfn backwards to the starting phase space point, the average of the backward projected spins will converge to the invariant spin direction linearly as 1/N where N is the number of turns tracked. The convergence can be accelerated by an iterative method that uses an approximate invariant spin field constructed by averaging the calculated spin field over points that are close in orbital phase space. This superconvergent algorithm has been built into a new program based upon the Bmad toolkit for charged particle and X-ray simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF028
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MOPMF067	Optimized Arc Optics for the HE-LHC	dipole, injection, sextupole, optics	277
	Y.M. Nosochkov, Y. Cai SLAC, Menlo Park, California, USA M.P. Crouch, M. Giovannozzi, M. Hofer, J. Keintzel, T. Risselada, E. Todesco, R. Tomás, F. Zimmermann CERN, Geneva, Switzerland D. Zhou KEK, Ibaraki, Japan L. van Riesen-Haupt JAI, Oxford, United Kingdom
	Funding: Work supported by the European Commission under Capacities 7th Framework Programme project EuCARD-2, grant agreement 312453, and the HORIZON 2020 project EuroCirCol, grant agreement 654305. The High Energy LHC (HE-LHC) proton-proton collider is a proposed replacement of the LHC in the existing 27-km tunnel, with the goal of reaching the centre-of-mass beam energy of 27 TeV. The required higher dipole field can be realized by using 16-T dipoles being developed for the FCC-hh design. A major concern is the dynamic aperture at injection energy due to degraded field quality of the new dipole based on Nb3Sn superconductor, the potentially large energy swing between injection and collision, and the slightly reduced magnet aperture. Another issue is the field in quadrupoles and sextupoles at top energy, for which it may be cost-effective, wherever possible, to stay with Nb-Ti technology. In this study, we explore design options differed by arc lattice, for three choices of injection energy, with the goal of attaining acceptable magnet field and maximum injection dynamic aperture with dipole non-linear field errors.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF067
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MOPMF079	The CEPC lattice design with combined dipole magnet	sextupole, dipole, collider, dynamic-aperture	315
	D. Wang, S. Bai, F.S. Chen, W. Chou, J. Gao, Y.M. Peng, Y. Wang, M. Yang, C.H. Yu, Y. Zhang IHEP, Beijing, People's Republic of China
	For the lattice of CEPC collider ring, the combined magnet (dipole+sextupole) scheme has been developed to reduce the power consumption of the stand-alone sextu-poles. The power consumption of sextupoles has been decreased by 75% due to 50% reduction of strength. The dynamic aperture for the combined magnet scheme is as good as the original lattice. The magnet design for this kind of combined dipole has been done which provides a good support for this new idea.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF079
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MOPMK002	Integrated Full HE-LHC Optics and Its Performance	dipole, injection, insertion, target	348
	M. Hofer TU Vienna, Wien, Austria M.P. Crouch, J. Keintzel, T. Risselada, R. Tomás, F. Zimmermann CERN, Geneva, Switzerland Y.M. Nosochkov SLAC, Menlo Park, California, USA D. Zhou KEK, Ibaraki, Japan L. van Riesen-Haupt JAI, Oxford, United Kingdom
	One possible future hadron collider design investigated in the framework of the Future Circular Collider (FCC) study is the High-Energy LHC (HE-LHC). Using the 16 T dipoles developed for the FCC-hh the center of mass energy of the LHC is set to increase to 27 TeV. To achieve this set energy goal, a new optics design is required, taking into account the constraint from the LHC tunnel geometry. In this paper, two different lattices for the HE-LHC are presented. Initial considerations take into account the physical aperture at the proposed injection energy as well as the energy reach of these lattices. The dynamic aperture at the injection energies is determined using latest evaluations of the field quality of the main dipoles.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK002
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MOPMK014	Resistive-Wall Impedance of Insertions for FCC-hh	impedance, insertion, optics, experiment	378
	B. Riemann, S. Khan DELTA, Dortmund, Germany S. Arsenyev, D. Schulte CERN, Geneva, Switzerland
	Funding: This work is supported by the German Ministry of Education & Research (BMBF, funding code 05P15PERB1) and CERN (reference numbers KE3123, EDMS 1606722). In this work, transverse and longitudinal resistive-wall impedances for beam pipes in the experiment, injection, extraction and RF systems insertion regions of the Future Hadron-Hadron Collider (FCC-hh) are computed based on contributions from different given cross sections of the surrounding (elliptical) chamber parts along the beam path, their temperature-dependent conductivities, and optical functions. An emphasis is placed on the behaviour of transverse impedance in the main experimental regions (A and G), where maximum beta values of 10⁴ to 10⁵ m occur in dependence of the operation mode respectively lattice configuration. Main contributions to the transverse and longitudinal impedance budget are identified, and possibilities of reducing them are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK014
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MOPML008	JLEIC Electron Ring Dynamic Aperture with Non-linear Field Errors	dynamic-aperture, electron, emittance, sextupole	404
	Y.M. Nosochkov, Y. Cai SLAC, Menlo Park, California, USA F. Lin, V.S. Morozov, G.H. Wei, Y. Zhang JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under US DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357. Work supported by the US DOE Contract DE-AC02-76SF00515. We present results of dynamic aperture study for the updated electron ring lattice of the Jefferson Lab Electron-Ion Collider (JLEIC). The lattice design features low emittance arcs with local compensation of sextupole non-linear effects, and low emittance non-linear chromaticity correction sections. Dynamic aperture tracking simulations are performed to evaluate the effects of non-linear field errors, the sensitivity to betatron tune, and the impact of momentum error. Dynamic aperture is also evaluated with the measured PEP-II field errors. Preliminary tolerances to the non-linear field errors in the Final Focus quadrupoles are estimated.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML008
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MOPML010	Challenges and Status of Tuning Simulations for CLIC Traditional Beam Delivery System	luminosity, linear-collider, collider, simulation	412
	R.M. Bodenstein, P. Burrows JAI, Oxford, United Kingdom E. Marín CERN, Geneva, Switzerland
	The beam delivery system (BDS) for the 3 TeV version of the Compact Linear Collider (CLIC) has two main design types. One type is referred to as the local scheme, as it is approximately one kilometer shorter and corrects the chromaticity in both planes. The other type is referred to as the traditional scheme, and separates the chromaticity correction of each plane into different areas. The expectation early in the studies was that the traditional scheme would be easier to tune. This work will address the problems experienced in tuning simulations for the traditional BDS and describe the current state of these simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML010
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MOPML061	Hadron Therapy Machine Simulations Using BDSIM	simulation, hadron, hadrontherapy, proton	546
	W. Shields JAI, Egham, Surrey, United Kingdom S.T. Boogert, L.J. Nevay Royal Holloway, University of London, Surrey, United Kingdom J. Snuverink PSI, Villigen PSI, Switzerland
	Minimising the background radiation dose in hadron therapy from particle losses and secondary emissions is of the highest importance for patient protection. To achieve this, tracking particles from source to the patient delivery region in a single simulation provides a quantitative description that distinguishes the background radiation from the treatment dose arriving at the gantry's isocentre. We demonstrate the ability to simulate beam transport, particle loss studies, and background radiation tracking in an example hadron therapy machine using BDSIM, a Geant4 based Monte Carlo simulation code for tracking high energy particles within a particle accelerator and its surrounding environment. Machine optics verification is also demonstrated through comparison to existing accelerator tracking codes.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML061
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TUPAF073	Simulation of Integrable Synchrotron with Space-charge and Chromatic Tune-shifts	space-charge, simulation, optics, synchrotron	894
	J.S. Eldred, A. Valishev Fermilab, Batavia, Illinois, USA
	We present a nonlinear rapid-cycling synchrotron designed as a high-intensity replacement of the Fermilab Booster. The design incorporates integrable optics, an innovation in particle accelerator design that enables strong nonlinear focusing without generating parametric resonances. We use the Synergia space-charge tracking code to demonstrate the stability of a beam in this lattice with a space-charge tune-shift up to 0.4 and a rms momentum spread up to 0.4\%. We demonstrate the benefit of increased lattice periodicity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF073
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TUPAL027	Design of Multi-MW Rapid Cycling Synchrotron for Accelerator Driven Transmutation System	extraction, acceleration, proton, synchrotron	1057
	Y. Fuwa Kyoto ICR, Uji, Kyoto, Japan N. Amemiya Kyoto University, Kyoto, Japan Y. Ishi, Y. Kuriyama, T. Uesugi Kyoto University, Research Reactor Institute, Osaka, Japan
	For the practical application of Accelerator Driven System (ADS) that reduces the harmfulness of radioactive waste by transmutation, we are studying the development of a compact accelerator using a synchrotron as an accelerator capable of supplying a stable proton beam to a nuclear reactor. In this plan, we aim to realize down-sizing and high reliability by adopting an alternating high temperature superconducting magnet and a high repetition synchrotron applying resonant beam extraction. In this presentation we report the basic design of the optical system and beam acceleration sequence of this synchrotron.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL027
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TUPAL058	Studies for Major ISIS Upgrades via Conventional RCS and Accumulator Ring Designs	injection, simulation, space-charge, emittance	1148
	C.M. Warsop, D.J. Adams, H.V. Cavanagh, P.T. Griffin-Hicks, B. Jones, B.G. Pine, R.E. Williamson STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	ISIS is the spallation neutron source at the Rutherford Appleton Laboratory in the UK, which provides 0.2 MW of beam power via a 50 Hz, 800 MeV proton RCS. Detailed studies are now under way to find the optimal configuration for a next generation, short pulsed neutron source that will define a major ISIS upgrade in ~2031. Accelerator configurations being considered for the MW beam powers required include designs exploiting FFAG rings as well as conventional accumulator and synchrotron rings. This paper describes work exploring the latter, conventional options, but includes the possibility of pushing further toward intensity limits to reduce facility costs. The scope of planned studies is summarised, looking at optimal exploitation of existing ISIS infrastructure, and incorporating results from recent target studies and user consultations. Results from initial baseline studies for an accumulator ring and RCS located in the existing ISIS synchrotron hall are presented. Injection scheme, foil limits, longitudinal and transverse beam dynamics optimization with related beam loss and activation are outlined, as are results from detailed 3D PIC simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL058
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TUPAL064	Extended-Domain Tune-Scans for the HL-LHC Dynamic Aperture in Presence of Beam-Beam Effects	resonance, octupole, dynamic-aperture, beam-beam-effects	1163
	D. Kaltchev TRIUMF, Vancouver, Canada N. Karastathis, Y. Papaphilippou, D. Pellegrini CERN, Geneva, Switzerland
	We report simulations of the HL-LHC dynamic aperture (DA) at collision energy in the presence of beam-beam effects (weak-strong approximation) aiming to determine its dependence on the working point in tune space. Both linear domains working points are explored, spanning over (0.028 – 0.33) in horizontal tune, and two-dimensional ones which focus on more promising sub-regions near the diagonal. The range of parameters, such as bunch intensity and emittance, are chosen to correspond to the more important HL-LHC scenarios. A comparison with the LHC as built is also made. Direct benefit from these studies is the possible identification of working points alternative to the nominal one (in terms of dynamic aperture). They also help to understand the dependence of DA on particular resonance lines present in the vicinity of the footprint. In this work, the necessary resources were provided by the LHC@home project, based on the BOINC-SixTrack platform for distributed Computing.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL064
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TUPMF011	Calculation of Expected Orbit Motion Due to Girder Resonant Vibration at the APS Upgrade	ground-motion, factory, resonance, quadrupole	1269
	V. Sajaev, Z. Liu, J. Nudell, C.A. Preissner ANL, Argonne, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The Advanced Photon Source (APS) is pursuing an upgrade to the storage ring that will provide electron beam with extremely low emittance. To allow users to take advantage of this small beam size, the beam orbit motion has to be kept stable to within a fraction of the beam size. To keep the beam orbit stable on a sub-micron level, one needs to carefully design magnet supports/girders so that the ground motion does not lead to excessive orbit motion due to resonant modes of magnet supports. In this paper, we will describe the process of calculating the expected orbit motion due to girder resonant vibration. First, we will present the simulation results for the girder resonant modes, then we will calculate the orbit amplification factors for the girder deformation modes, then calculate the expected orbit motion using measured ground motion spectrum. This process can be used to evaluate the design of the magnet supports.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF011
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TUPMF012	Determination of the Ground Motion Orbit Amplification Factors Dependence on the Frequency for the APS Upgrade Storage Ring	ground-motion, factory, storage-ring, simulation	1272
	V. Sajaev, C.A. Preissner ANL, Argonne, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The Advanced Photon Source (APS) is pursuing an upgrade to the storage ring that will provide electron beam with extremely low emittance. To allow users to take advantage of this small beam size, the beam orbit motion has to be kept stable to within a fraction of the beam size, which translates to sub-micron orbit stability requirement. Ground motion provides significant contribution to the overall expected beam motion, especially at lower frequencies where the ground motion has larger amplitudes. At the same time, the lattice amplification factors reduce when the ground motion becomes coherent at low frequencies. In this paper, we will present simulation of the lattice amplification factor dependence on the ground motion coherence length and show results of the ground motion coherence measurements at APS. After that, we will determine the lattice amplification factors dependence on the ground motion frequency, that can be used to calculate the expected effect of the ground motion on the orbit stability.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF012
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TUPMF013	Optimizations of Nonlinear Beam Dynamics Performance on APS-U Lattice	MMI, sextupole, multipole, storage-ring	1276
	Y.P. Sun, M. Borland ANL, Argonne, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. For next-generation storage ring light sources, such as the Advanced Photon Source (APS) Multi-Bend Achromat (MBA) upgrade, the strong nonlinearities introduced by the strong chromaticity sextupoles plus the small physical apertures make it challenging to achieve large dynamic acceptance (DA) and long Touschek lifetime, even when using the on-axis swap-out injection scheme. Several different methods have been explored for nonlinear dynamics optimization. The optimization objectives variously include the chromaticities up to third order, resonance driving and detuning terms, on- and off-momentum dynamic acceptance, chromatic and geometric tune footprint, local momentum acceptance (LMA), variation of betatron oscillation invariant, Touschek lifetime, etc. In addition, optimization can be performed without errors, with selected random errors, and with sets of errors that reflect post-commissioning conditions. In this paper, these different optimization methods are compared for the nonlinear beam dynamics performance of the Advanced Photon Source upgrade (APS-U) lattice, in terms of the dynamic acceptance, local momentum acceptance, and other performance measures. The impact from different error sources is also studied.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF013
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TUPMF035	First Demonstration of the Transparent Fast-to-slow Corrector Current Shift in the NSLS-II Storage Ring	feedback, experiment, operation, photon	1323
	X. Yang, V.V. Smaluk, Y. Tian, L. Yu BNL, Upton, Long Island, New York, USA
	To realize the full benefits of the high brightness and ultra-small beam sizes of NSLS-II, it is essential that the photon beams are exceedingly stable (a level of 10% beam size). In the circumstances of implementing local bumps, changing ID gaps, and long-term drifting, the fast orbit feedback (FOFB) requires shifting the fast corrector strengths to the slow correctors to prevent the fast corrector saturation and to make the beam orbit stable in the sub-micron level. As the result, a reliable and precise technique of fast-to-slow corrector strength shift has been developed and tested at NSLS-II. This technique is based on the fast corrector response to the slow corrector change when the FOFB is on. In this article, the shift technique is described and the result of proof-of-principle experiment carried out at NSLS-II is presented. The maximum fast corrector current was reduced from greater than 0.45 A to less than 0.04 A with the orbit perturbation within ±1 μm. Especially when the step size of the shift was below 0.012 A, the amount of noise being added to the beam was none.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF035
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TUPMF038	Design Considerations for an Ultralow Emittance Storage Ring for the Canadian Light Source	emittance, sextupole, quadrupole, electron	1334
	L.O. Dallin CLS, Saskatoon, Saskatchewan, Canada
	Demands from light source scientists for more brilliant xray beams have resulted in the emergence of 4th generation storage rings. These demands include photon beams that are highly focussed and beams with high transverse coherence. Both these requirements are achieved with ultralow electron beam emittance. The practical development of the multi-bend achromat (MBA) concept by MAX IV has spurred many synchrotron light sources around the world to develop similar machines. For existing facilities two options are available: upgrading existing machines or building a new structure. The Canadian Light Source (CLS) has explored both options and has determined a new storage ring is required. Several design options for a 3.0 GeV ring have been developed. Best results are achieved when tracking is used to optimize the phase advance through the MBA structure to reduce the impact of the sextupoles on the dynamic aperture. Structures where no geometric sextupoles are required have been achieved while producing ultralow emittances.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF038
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TUPMF049	Evolution of the Lattice Design for the High Energy Photon Source	emittance, storage-ring, injection, photon	1363
	G. Xu, S.Y. Chen, Y. Jiao, J.L. Li, Y.M. Peng, Q. Qin, J.Q. Wang, C.H. Yu IHEP, Beijing, People's Republic of China
	The High Energy Photon Source (HEPS) is a high-energy, ultralow-emittance, kilometer-scale storage ring light source to be built in China. The HEPS lattice design has been started since 2008. In this paper we will review the evolution of the HEPS lattice design over the past ten years, focusing mainly on the linear optics design and nonlinear optimization.
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TUPMF050	DA Optimization Experiences in the Heps Lattice Design	sextupole, emittance, photon, storage-ring	1367
	Y. Jiao, G. Xu IHEP, Beijing, People's Republic of China
	In the past decade, the so-called diffraction-limited storage ring (DLSR) light sources were proposed, promising much better radiation performance than available in the existing third generation light sources. Regarding the very strong focusing and chromatic sextupoles that required for reaching an ultralow emittance, to optimize the nonlinear dynamics and achieve an adequate dynamic aperture is an important topic in a DLSR design. In this paper we will present some tips distilled from the DA optimization experience of the High Energy Photon Source over the past ten years, hoping it could provide some aids to other ultralow-emittance designs.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF050
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TUPMF052	Progress of Lattice Design and Physics Studies on the High Energy Photon Source	booster, storage-ring, injection, emittance	1375
	G. Xu, X. Cui, Z. Duan, Z. Duan, Y.Y. Guo, D. Ji, Y. Jiao, J.L. Li, X.Y. Li, C. Meng, Y.M. Peng, Q. Qin, S.K. Tian, J.Q. Wang, N. Wang, Y. Wei, H.S. Xu, F. Yan, C.H. Yu, Y.L. Zhao IHEP, Beijing, People's Republic of China
	The High Energy Photon Source (HEPS) is an ultralow-emittance, kilometer-scale storage ring light source to be built in China. In this paper we will introduce the progress of the physical design and studies on HEPS over the past one year, covering issues of storage lattice design and optimization, booster design, injection design, collective effects, error study, insertion device effects, beam lifetime, etc.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF052
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TUPMF054	Performance Comparison of Different Ultralow Emittance Unit Cells	emittance, dipole, storage-ring, quadrupole	1382
	Y. Jiao, X.Y. Li, G. Xu IHEP, Beijing, People's Republic of China
	The available minimum emittance of a storage ring and the ring performance is closely related to the unit cell of the lattice. Up to now, several ultralow-emittance unit cells have been proposed and applied in the lattice design of the diffraction-limited storage ring light sources. In this study we quantitatively compared the performance of three typical unit cells, based on mainly the parameters of the High Energy Photon Source. The results indicate that the modified-TME unit cell with antibend and longitudinal gradient dipole allows the lowest possible emittance, given a long enough cell length.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF054
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TUPMF056	Brightness Dependence Investigation and Optimizaiton for the Heps	brightness, emittance, photon, undulator	1390
	Y. Jiao, M. Li, X.Y. Li IHEP, Beijing, People's Republic of China
	The High Energy Photon Source (HEPS) is an ultralow-emittance, kilometer-scale storage ring light source to be built in China. To maximize the photon spectral brightness, one of the most important performance parameters of the light source, we investigated the dependence of brightness on different parameters, such as the natural emittance, coupling, beta functions of the undulator section, and length of the undulator section. Based on this study, we optimized the HEPS lattice by using brightness as an optimizing objective.
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TUPMF059	Error Study of HEPS Booster	closed-orbit, booster, multipole, simulation	1398
	C. Meng, D. Ji, J.L. Li, Y.M. Peng IHEP, Beijing, People's Republic of China
	The High Energy Photon Source (HEPS) is a 6-GeV, ultralow-emittance light source to be built in China. The injector is composed of a 500-MeV linac and a full energy booster with 1 Hz repetition frequency. The detailed error study of the booster will be presented, including misalignment errors and closed orbit correc-tion, magnetic field errors and power supply errors. The effect of errors on closed orbit, tune, chromaticity and dynamic aperture will be discussed. The dynamic aperture with multipole errors will be presented also.
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TUPMF060	Design of Bunch Lengthening System in Electron Linac	linac, booster, photon, bunching	1401
	C. Meng, Y. Jiao, J.L. Li, S. Pei, Y.M. Peng, H.S. Xu IHEP, Beijing, People's Republic of China
	The High Energy Photon Source (HEPS) is a 6-GeV, ultralow-emittance light source to be built in China. The injector is composed of a linac and a full energy booster. To increase the threshold of TMCI in the booster, the HEPS linac design has been evolved with several iterations. The important middle-version design is a 300 MeV linac with rms bunch length larger than 20 ps. One bunch lengthening system is proposed and discussed in this paper.
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TUPMF062	Status of HEPS Booster Lattice Design and Physics Studies	booster, injection, storage-ring, extraction	1407
	Y.M. Peng, Z. Duan, Y.Y. Guo, D. Ji, Y. Jiao, J.L. Li, C. Meng, S.K. Tian, H.S. Xu IHEP, Beijing, People's Republic of China
	The High Energy Photon Source (HEPS) with an ul-tralow emittance is proposed to be built in Beijing, Chi-na. It will utilize a booster as its full energy injector. On-axis swap-out injection is chosen as the baseline injec-tion scheme for the storage ring. As required by the stor-age ring, a beam with a bunch charge up to 2.5 nC is needed to be injected in the booster. However, limited by the transverse mode coupling instability (TMCI), such a high bunch charge is challenging. To overcome this problem, a lattice with a considerable large momentum compaction factor is designed. This paper reports the lattice design and physics studies of the HEPS booster, including injection and extraction design, error studies, eddy current effects, collective effects, and so on.
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TUPMF063	The Considerations of Improving TMCI Threshhold on HEPS Booster	booster, linac, storage-ring, injection	1411
	Y.M. Peng, J.L. Li, C. Meng, S. Pei, H.S. Xu IHEP, Beijing, People's Republic of China
	The High Energy Photon Source (HEPS) is proposed in Beijing, China. The on-axis swap-out injection scheme will be used in the storage ring mainly because of the small dynamic aperture. Therefore, the booster needs to store more than 2.5 nC bunch charge. Under this requirement, the transverse mode coupling instability (TMCI) at the injection energy becomes the bunch charge restriction in the booster. Several changes in booster and linac for improving bunch charge threshold limited by TMCI are considered. The details will be expressed in this paper.
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TUPMF068	Beam Dynamics on a Coupling Resonance at PETRA III	resonance, coupling, optics, injection	1417
	I.V. Agapov, J. Keil, G. Kube, G.K. Sahoo, R. Wanzenberg DESY, Hamburg, Germany Y.-C. Chae ANL, Argonne, Illinois, USA A.I. Novokshonov TPU, Tomsk, Russia
	Working on a coupling resonance is a usual way of producing round beams in a synchrotron. The beam dynamics in this regime is however more complicated, and the emittance is sensitive to the working point, coupling correction, and bunch current drop with time, which complicates the operation. We present experience with optics setup for working on a coupling resonance in PETRA III, including linear and nonlinear beam optics characteristics, and the measurement of the horizontal and vertical beam emittances with a 2D interferometer. Beam dynamics on a coupling resonance for PETRA IV, the MBA upgrade of PETRA III currently under consideration, is also presented.
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TUPMF071	Status of Impedance Modeling for the PETRA IV	impedance, wakefield, synchrotron, status	1423
	Y.-C. Chae, R. Wanzenberg DESY, Hamburg, Germany
	The diffraction limited synchrotron light source envisioned for the PETRA IV project will require strong focusing to produce the small emittances in both planes. The large natural chromaticity together with small dispersion will require very strong sextupoles. In order to cope with high gradient magnets the radius of vacuum chamber tends to be in the range of 10 mm, which is very small compared to the current 40-mm wide elliptic chamber. The impedance element in the PETRA III was scaled down to fit into the smaller aperture so that the short range wakepotential can be computed numerically. For instance the beam position monitor (BPM) was reduced to 60% in dimension so that it can be used in PETRA IV. Even if the actual design of hardware does not exist yet, we assume that generic feature of PETRA III model is still valid. In this paper we report the up-to-date information on impedance model of PETRA IV together with the preliminary impedance budget based on the analytical formula. We also report the specific studies carried out to understand the kickfactor scaling with the chamber aperture whose radius is in the range of 8-12 mm.
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TUPMF073	Impedance Optimization of Small Gap Chambers for the High Single Bunch Current Operation at the Undulator Based Light Sources	impedance, undulator, ECR, simulation	1430
	Y.-C. Chae DESY, Hamburg, Germany
	In the undulator based light sources the intensity limit of single bunch is often determined by the strong vertical instability caused by the wakefield in the ring, where the undulator itself is large impedance source. The optimization of transition from the large aperture to undulator's small-gap chamber is on-going research topic in an effort to reduce the vertical impedance; at the same time, the demand on single-bunch current is high from the timing-mode x-ray user community. In this paper, after showing the results obtained by exploring the parameter space guided by Stupakov's formula, we propose the linearly-segmented transition which can reduce the impedance down to 60% or less of the original linear taper. The reduction can be utilized either to increase the bunch current substantially or to install a smaller gap chamber without impacting the bunch current limit. For the definite result we considered the transition between two ellipses, namely, (a, b) = (42 mm, 21 mm) and (18 mm, 4 mm) over the length 15-30 cm in beam direction.
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TUPMF074	Control of Collective Effects by Active Harmonic Cavity in an MBA-based Light Source with Application to the PETRA Upgrade	cavity, impedance, emittance, synchrotron	1433
	Y.-C. Chae, J. Keil DESY, Hamburg, Germany
	Based on the reference lattice for PETRA IV* we investigated collective effects with non-zero current. Out of many possibilities we firstly computed the intrabeam-scattering (IBS) effects on the emittance as well as lifetime as a function of current. The result indicated that PETRA IV would benefit from the reduced peak current when the harmonic cavity lengthens the bunch. The operating point of harmonic cavity was explored by tracking simulations as well as analytic formula. In order to compute the energy spread and bunch length we had used the known impedance function of the APS*. In this way more realistic estimation of IBS effects was expected. However, because of the complex nature of PETRA IV lattice, which includes achromatic cells for undulators, arc cells of octants and straight sectors for damping wigglers, we simplify the longitudinal dynamics by assuming the ring made of 92 multi-bend-achromat (MBA) cells. The optics is approximated as a linear-chromatic transfer map enabling fast tracking and the ring impedance is concatenated into the one location. The detailed collective effects with and without harmonic cavities are presented in the paper. J. Keil, "A PETRA IV Lattice Based on Hybrid Seven Bend Achromats", these proceedings. ** Y.-C. Chae and Y. Wang, "Impedance Database II for the Advanced Photon Source Storage Ring", Proc. PAC2007.
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TUPMF075	Lattice Studies of a Booster Synchrotron for PETRA IV	emittance, booster, damping, optics	1436
	H.C. Chao DESY, Hamburg, Germany
	Associated with an upgrade study of the PETRA III light source toward ultra low-emittance is an upgrade study of the booster synchrotron. One possible solution obtained from a scaling of the ALBA booster to a circumference of 300 m is considered. It is based on a modified FODO lattice with combined function magnets and achromat straights. In this paper a method utilizing piecewise matchings supervised and optimized with evolutionary algorithm (PMSOEA) was devised to search the lattice. Some preliminary results are shown and discussed.
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TUPMK003	Advances in the Sirius Delta-Type Undulator Project	undulator, polarization, storage-ring, MMI	1491
	L.N.P. Vilela, R. Basílio, J.F. Citadini, J.R. Furaer, F. Rodrigues LNLS, Campinas, Brazil
	The Delta undulator is a compact adjustable-phase insertion device that provides full light polarization control. Five undulators of this type will be installed in the initial operation phase of Sirius, the new 4th generation synchrotron light source that is being built by the Brazilian Synchrotron Light Laboratory (LNLS). In this work we present the recent advances in the development of Sirius Delta-type undulator, the studies of the effects of this device in the storage ring beam dynamics and assembly and measurements strategies.
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TUPMK014	Dipole Fringe Field Analysis of the NSLS-II Storage Ring	dipole, storage-ring, optics, simulation	1519
	J. Choi, Y. Hidaka, T.V. Shaftan, C.J. Spataro, G.M. Wang BNL, Upton, Long Island, New York, USA
	Funding: DOE Contract No. DE-SC0012704 In the NSLS-II storage ring, the effect of the dipole fringe field is not negligible and was considered already at the design phase. Especially in the vertical direction, the standard simulation codes are using the parameter called FINT (fringe Field INTegral) and, if there is no specific information, it is usually set to 0.5 which is considered as the reasonable average. With the hall-probe measurement data of the NSLS-II storage ring dipoles, we evaluated measured FINTs and applied them to the beam simulation. The paper shows the resulting FINTs and their effects.
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TUPMK018	Round Beam Studies at NSLS-II	coupling, emittance, resonance, experiment	1529
	Y. Hidaka, W.X. Cheng, Y. Li, T.V. Shaftan, G.M. Wang BNL, Upton, Long Island, New York, USA
	Funding: The study is supported by U.S. DOE under Contract No. DE-AC02-98CH10886. Instead of typical flat beam, some synchrotron light us-ers prefer round beam, i.e., with equal horizontal and vertical emittance, for various reasons (e.g., simplified optics, smaller fraction of photons getting discarded, better phase space match between photon and e-beam). Several future upgrade storage rings such as APS-U, ALS-U, and SLS-2 currently plan to operate in round beam mode. We report our beam study results on round beam operating at NSLS-II by driving linear difference cou-pling resonance.
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TUPML017	Longitudinal Phase Space Reconstruction at FLASHForward Using a Novel Transverse Deflection Cavity, PolariX-TDS	plasma, experiment, dipole, simulation	1567
	R.T.P. D'Arcy, A. Aschikhin, P. González Caminal, V. Libov, J. Osterhoff DESY, Hamburg, Germany
	The FLASHForward project at DESY is an innovative beam-driven plasma-wakefield acceleration (PWFA) experiment, aiming to accelerate electron beams to GeV energies over a few centimeters of ionized gas. These accelerated beams are assessed for their capability to drive a free-electron laser. The ultra short, low emittance, and low energy spread properties of bunches produced from certain PWFA injection schemes naturally lend themselves to this task. However, these bunch lengths, typically in the few femtosecond range, are difficult to temporally resolve with traditional diagnostic methods. In order to longitudinally diagnose these bunches it is necessary to utilise the properties of a transverse RF deflecting cavity operating in a high-frequency regime. It is proposed that this type of X-band transverse deflection system, styled the PolariX-TDS due to its novel variable polarisation feature, will be introduced to the FLASHForward beam line in order to perform these single-shot longitudinal phase space measurements. This paper will concern itself with the efficacy of longitudinally reconstructing PWFA-bunches expected at FLASHForward with this TDS, with a focus on the variable bunch properties expected from early commissioning of the experiment.
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TUPML038	Simulation of Phase-Dependent Transverse Focusing in Dielectric Laser Accelerator Based Lattices	focusing, laser, emittance, quadrupole	1622
	F. Mayet, R.W. Aßmann, U. Dorda, W. Kuropka DESY, Hamburg, Germany W. Kuropka, F. Mayet University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
	Funding: Gordon and Betty Moore Foundation. Grant GBMF4744 The Accelerator on a CHip International Program (ACHIP) funded by the Gordon and Betty Moore Foundation aims to demonstrate a prototype of a fully integrated accelerator on a microchip based on laser-driven dielectric structures until 2021. Such an accelerator on a chip needs all components known from classical accelerators. This includes an electron source, accelerating structures and transverse focusing arrangements. Since the period of the accelerating field is connected to the drive laser wavelength of typically a few microns, not only longitudinal but also transverse effects are strongly phase-dependent even for few femtosecond long bunches. If both the accelerating and focusing elements are DLA-based, this needs to be taken into account. In this work we study in detail the implications of a phase-dependent focusing lattice on the evolution of the transverse phase space of a transported bunch.
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TUPML067	Recent Results from the Study of Emittance Evolution in MICE	emittance, solenoid, detector, experiment	1699
	V. Blackmore Imperial College of Science and Technology, Department of Physics, London, United Kingdom
	Funding: STFC, DOE, NSF, INFN, and CHIPP The Muon Ionization Cooling Experiment (MICE) has measured the evolution of emittance due to ionization energy loss. Muons were focused onto an absorber using a large aperture solenoid. Lithium-hydride and liquid hydrogen-absorbers have been studied. Diagnostic devices were placed upstream and downstream of the focus, enabling the phase-space coordinates of individual muons to be reconstructed. By observing the properties of ensembles of muons, the change in beam emittance was measured. Data taken during 2016 and 2017 are currently under study to evaluate the change in emittance due to the absorber for muon beams with various initial emittance, momenta, and settings of the magnetic lattice. The current status and the most recent results of these analyses will be presented.
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WEXGBE2	Compensation of Insertion Device Induced Emittance Variations in Ultralow Emittance Storage Rings	emittance, wiggler, electron, photon	1751
	F. Sannibale, S.C. Leemann, H. Nishimura, D. Robin, C. Steier, C. Sun, M. Venturini LBNL, Berkeley, California, USA
	Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231. With the advent of multi-bend achromat lattices, extremely low emittances are to become the norm in storage ring-based X-ray photon sources. In these lattices, the ratio of beam energy lost to radiation in the Insertion Devices (IDs) to the overall beam energy loss is relatively larger than in 3rd generation light sources. As a result, these machines are more sensitive to the energy loss variations occurring as the users operate variable-gap IDs and to the concurrent variations in radiation damping time, equilibrium emittance, and ultimately transverse properties of the beam. With possibly tens of variable gap IDs continuously and independently varying their gaps to meet the experiment needs, the resulting variation in emittance and beam sizes can be significant and can jeopardize the experimental performance in some of the beamlines. In this paper we describe and discuss possible methods for compensating such emittance variations and maintaining constant transverse beam properties for the experiments.
	Slides WEXGBE2 [4.543 MB]
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WEYGBE1	Suppressing CSR Microbunching in Recirculation Arcs	bunching, dipole, emittance, radiation	1784
	C.-Y. Tsai SLAC, Menlo Park, California, USA
	We provide sufficient conditions for suppression of CSR-induced microbunching instability along transport or recirculation arcs. The example lattices include low-energy (∼100 MeV) and high-energy (∼1 GeV) recirculation arcs, and medium-energy compressor arcs. Our studies show that lattices satisfying the proposed conditions indeed have microbunching gain suppressed. Beam current dependencies of maximal CSR microbunching gains are also demonstrated, which should help outline a beam line design for different scales of nominal currents. We expect this analysis can improve future lattice design.
	Slides WEYGBE1 [10.975 MB]
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WEPAF009	Optimising Response Matrix Measurements for LOCO Analysis	storage-ring, coupling, distributed, quadrupole	1826
	Y.E. Tan AS - ANSTO, Clayton, Australia
	The Linear Optics from Closed Orbit (LOCO) method is a common tool for determining storage ring lattice functions and requires a measured BPM to Corrector response matrix. For very large rings with many correctors, such measurements can be time consuming. The following study investigates how the number of correctors and the signal-to-noise ratio (SNR) affects the LOCO analysis results. For the Australian Synchrotron, the results show that four distributed correctors per plane with a SNR of >1000 is sufficient to fit the betatron functions to an accuracy of less than 0.2%.
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WEPAF032	An Alternative Fast Orbit Feedback Design of HEPS	feedback, emittance, controls, closed-orbit	1888
	X.Y. Huang, J.S. Cao, Y.Y. Du, F. Liu, Y.H. Lu, Y.F. Ma, Y.F. Sui, S.J. Wei, Q. Ye, X.E. Zhang, D.C. Zhu IHEP, Beijing, People's Republic of China
	The High Energy Photon Source (HEPS) is a fourth generation light source in China and will be built in this year. The emittance of HEPS storage ring is approaching diffraction limit and the circumstance of the ring is about 1.3 kilometres. To stabilize the electron beam, fast orbit feedback (FOFB) system is prerequisite. In this paper, the requirements on the HEPS beam stability are discussed and an alternative FOFB design based on DBPM are introduced with algorithm and architecture.
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WEPAF041	Use of Dimension-Reduction Techniques With Multi-Objective Genetic Algorithms to Improve the Vertical Emittance and Orbit at CESR	emittance, storage-ring, simulation, electron	1901
	W.F. Bergan, I.V. Bazarov, C.J. Duncan, D. L. Rubin Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA D. Liarte, J.P. Sethna Cornell University, Ithaca, New York, USA
	Funding: DOE DE-SC0013571 NSF DGE-1650441 In order to reduce the vertical emittance at the Cornell Electron Storage Ring (CESR), we first measure and correct the vertical orbit, dispersion, and coupling. However, due to the finite resolution of our optics measurements, we still retain a significant residual emittance. In order to correct this further, we made use of the theory of sloppy models, according to which certain high-dimensionality systems can be modeled with significantly fewer "eigenparameters" that still contain most of the effect on the desired objective, in this case, the emittance.* However, we noted that using these knobs for tuning often resulted in increased vertical orbit errors. In an attempt to constrain these, we have applied multi-objective genetic algorithms to this problem. We have found that it can be more efficient to run such algorithms using our eigenparameters as the genes to be varied, as opposed to the raw magnet values. When running with the first 8 such knobs as genes, we can get either orbits or beam sizes as good as we obtain with our regular emittance-tuning algorithm which uses all the corrector magnets. *K.S. Brown and J.P. Sethna, Phys. Rev. E 68, 021904 (2003).
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WEPAF050	Simulations of 3D Charge Density Measurements for Commissioning of the PolariX-TDS	cavity, simulation, electron, MMI	1930
	D. Marx, R.W. Aßmann, R.T.P. D'Arcy, B. Marchetti DESY, Hamburg, Germany
	The prototype of a novel X-band transverse deflection structure, the Polarizable X-band (PolariX) TDS, is currently being prepared for installation in the FLASHForward beamline* at DESY in early 2019. This structure will have the novel feature of variable polarization of the deflecting mode, allowing bunches to be streaked at any transverse angle, rather than at just one angle as in a conventional cavity. By combining screen profiles from several streaking angles using tomographic reconstruction techniques, the full 3D charge density of a bunch can be obtained**. It is planned to perform this measurement for the first time during commissioning of the structure. In this paper, simulations of this measurement are presented and the effects of jitter are discussed. P Craievich et al. paper THPAL068, this conference A Aschikhin et al. Nucl. Instr. Meth. Phys. Res. A., vol.806, pp.175-183, 2018 *D Marx et al. J. Phys.: Conf. Ser., vol.874, p.012077, 2017
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WEPAF054	Online Multi Objective Optimisation at Diamond Light Source	injection, sextupole, controls, EPICS	1944
	M. Apollonio, R. Bartolini, R.T. Fielder, I.P.S. Martin DLS, Oxfordshire, United Kingdom R. Bartolini JAI, Oxford, United Kingdom G. Henderson Oxford University, Physics Department, Oxford, Oxon, United Kingdom J. Rogers Imperial College of Science and Technology, Department of Physics, London, United Kingdom
	At Diamond Light Source we have developed an Optimization Package currently used online to improve the performance of the machine, usually measured in terms of lifetime, injection efficiency or beam disturbance at injection. The tool is flexible in that control variables in order to optimise objectives (or their functions) can be easily specified by means of EPICS process variables (PV), making it suitable for virtually any sort of optimization. At present three different algorithms can be used to perform optimizations in a multi-objective fashion: Multi-Objective Genetic Algorithm (MOGA), Particle Swarm Optimizer (MOPSO) and Simulated Annealing (MOSA). We present a series of tests aimed at characterizing the algorithm as well as improving the performance of the machine itself.
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WEPAL062	Bunch Length Measurements with a Streak Camera in Low Alpha Lattice Operation at the TPS	synchrotron, operation, photon, emittance	2316
	C.H. Chen, J.Y. Chen, M.-S. Chiu, P.J. Chou, K.T. Hsu, K.H. Hu, C.-C. Kuo, C.C. Liang, C.Y. Liao, Y.-C. Liu, G.-H. Luo, H.-J. Tsai, F.H. Tseng NSRRC, Hsinchu, Taiwan
	We developed and tested lattice with lower momentum compaction factor (low alpha) in TPS (Taiwan Photon Source) recently. Operating low alpha lattice can provide picosecond bunch length for time-resolved research and coherent IR/THz synchrotron light. The bunch length around 2.5 picosecond rms was measured by a streak camera* in low alpha mode while operating in the routine users mode** it was around 10 picosecond. This paper presents the related processes and measurements. * L.Y. Liao et al., "Preliminary beam test of synchrotron radiation monitoring system at Taiwan Photon Source", IPAC'15. ** C.C. Kuo et al., "Commissioning of Taiwan Photon Source", IPAC'15.
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WEPMF011	Design and Status of Sirius Light Source RF Systems	cavity, storage-ring, booster, LLRF	2391
	R.H.A. Farias, A.P.B. Lima, L. Liu, F.S. Oliveira LNLS, Campinas, Brazil
	Sirius is the new synchrotron light source currently under construction at the site of the Brazilian Synchro-tron Light Laboratory (LNLS) in Campinas, Brazil. The facility comprises a 3 GeV electron storage ring, a full energy booster and a 150 MeV linac. This work provides a brief description of the RF system of the booster and storage ring, presenting their main characteristics and specification goals.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF011
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WEPMF021	Magnet Design Considerations for an Ultralow Emittance Canadian Light Source	quadrupole, emittance, storage-ring, FEL	2413
	L.O. Dallin, D. Bertwistle CLS, Saskatoon, Saskatchewan, Canada
	The strong focusing requirements for ultralow emittance light sources result in high field magnets that are very close together. High fields are readily achieved by using small magnet gaps. This is possible due to the small beam sizes involved. Reduction in the physical aperture and the reduction in the good field region requirements results in magnets with compact transverse dimensions. The very strong focusing of the magnets results in very small drift spaces between the various magnetic elements. To keep these drift spaces clear magnets with recessed coils have been studied. In such magnets the coils do not stick out beyond the end of the magnet yoke in the longitudinal direction. By placing the coils on the outer yoke loss of efficiency can be avoided while maintaining good control of the higher order field harmonics. This is very well suited for quadrupole magnets where only two coils are required. Possible designs for gradient dipoles and sexutpoles are also considered.
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WEPMF035	Investigating the Effect of Inhomogeneous Resistivity on Bulk RRR and Heat Conductivity Using a Lattice Green's Functions Method	cavity, network, niobium, HOM	2436
	N.C. Shipman, A. Macpherson CERN, Geneva, Switzerland G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom J.A. Mitchell Lancaster University, Lancaster, United Kingdom
	A method was developed to calculate the bulk RRR (residual resistivity ratio) which would be measured on a superconducting cavity or sample with an inhomogeneous resistivity and arbitrary geometry. The method involves modelling the object as a network of resistors and employs lattice Green's functions. A further adaptation of the method which allows the heat transport characteristics of such an object to be predicted is also described.
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THXGBD1	The Upgrade of the Advanced Photon Source	feedback, controls, cavity, simulation	2872
	M. Borland, M. Abliz, N.D. Arnold, T.G. Berenc, J.M. Byrd, J.R. Calvey, J.A. Carter, J. Carwardine, H. Cease, Z.A. Conway, G. Decker, J.C. Dooling, L. Emery, J.D. Fuerst, K.C. Harkay, A.K. Jain, M.S. Jaski, P.S. Kallakuri, M.P. Kelly, S.H. Kim, R.M. Lill, R.R. Lindberg, J. Liu, Z. Liu, J. Nudell, C.A. Preissner, V. Sajaev, N. Sereno, X. Sun, Y.P. Sun, S. Veseli, J. Wang, U. Wienands, A. Xiao, C. Yao ANL, Argonne, Illinois, USA A. Blednykh BNL, Upton, Long Island, New York, USA
	After decades of successful operation as a 7-GeV synchrotron radiation source, the Advanced Photon Source is pursing a major upgrade that involves replacement of the storage ring with an ultra-low emittance multi-bend achromat design. Using a seven-bend hybrid multi-bend achromat with reverse bending magnets gives a natural emittance of 42 pm operated at 6 GeV. The x-ray brightness is predicted to increase by more than two orders of magnitude. Challenges are many, but appear manageable based on thorough simulation and in light of the experience gained from world-wide operation of 3^\text{rd}-generation light sources. The upgraded ring will operate in swap-out mode, which has allowed pushing the performance beyond the limits imposed by conventional operation.
	Slides THXGBD1 [14.684 MB]
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THPAF014	Studies of the Single-Bunch Instabilities in the Booster of HEPS	booster, impedance, storage-ring, injection	2971
	H.S. Xu, Z. Duan, J.L. Li, Y.M. Peng, S.K. Tian, N. Wang IHEP, Beijing, People's Republic of China
	High Energy Photon Source (HEPS), which is proposed in China, is an ultra-low emittance storage ring based synchrotron light source. Because of the requirement of the relatively high single-bunch charge, the booster may suffer from the single-bunch instabilities. A preliminary impedance model has been developed for the studies of collective instabilities in the booster. Based on this impedance model, the longitudinal and transverse single-bunch instabilities have been studied.
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THPAF021	Start to End Simulation of the CBETA Energy Recovery Linac	linac, simulation, optics, space-charge	2993
	W. Lou, A.C. Bartnik, J.A. Crittenden, C.M. Gulliford, G.H. Hoffstaetter, D. Sagan Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA J.S. Berg, S.J. Brooks, F. Méot, D. Trbojevic, N. Tsoupas BNL, Upton, Long Island, New York, USA C.E. Mayes SLAC, Menlo Park, California, USA
	Funding: This manuscript has been authored by employees of Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. CBETA is an energy recovery linac accelerating from 6 MeV to 150 MeV in four linac passes, using a single return line accepting all energies from 42 MeV to 150 MeV. We simulate a 6-dimensional particle distribution from the injector through the end of the dump line. Space charge forces are taken into account at the low energy stages. We compare results using field maps to those using simpler magnet models. We introduce random and systematic magnet errors to the lattice, apply an orbit correction algorithm, and study the impact on the beam distribution.
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THPAF022	Beam Breakup Studies for the 4-Pass Cornell-Brookhaven Energy Recovery Linac Test Accelertor	HOM, simulation, cavity, dipole	2996
	W. Lou, G.H. Hoffstaetter Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Cornell University and Brookhaven National Laboratory are currently designing the Cornell-BNL ERL-FFAG Test Accelerator (CBETA). To be built at Cornell Wilson Lab, CBETA utilizes the existing ERL injector and main linac cryomodule (MLC). As the electron bunches pass through the MLC cavities, higher order modes (HOMs) fields are excited. The recirculating bunches interact with the HOMs, which can give rise to beam-breakup instability (BBU). We would present simulation results on how BBU limits the maximum achievable current, and potential ways to improve the threshold current.
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THPAF028	Multi-Objectives Genetic Algorithms (MOGA) Optimization of PETRA IV Scenarios	injection, sextupole, SRF, dynamic-aperture	3015
	X.N. Gavaldà, J. Keil, R. Wanzenberg DESY, Hamburg, Germany
	This paper reports the application of Multi-Objective Genetic Algorithms (MOGA) to optimize the linear and nonlinear beam dynamics of the different PETRA IV scenarios to transform PETRA III storage ring in a diffracted limited one. As it is well known, the dynamic aperture and momentum acceptance of these kinds of lattices are dramatically reduced due to the increase of the sextupoles strengths to compensate its strong focusing. The reduction of the dynamic aperture jeopardizes the current off-axis injection system and lower beam lifetimes increase the beam instabilities and the radiation safety concerns of the storage ring. MOGA searches the best settings of quadrupoles and sextupoles in a multi-dimensional parameter space taking into account the dynamic properties and the natural emittance as objectives at the level of ten picometers. The lattices studied are the so-called 'Twist lattice' based in a phase space exchange lattice, a solution based in the ESRF-Hybrid Multi-bend Achromat (HMA) design and finally the 'double 'I' lattice combining a non-interleaved sextupoles cell with an ESRF-HMA cell.
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THPAF031	A PETRA IV Lattice based on Hybrid Seven Bend Achromats	emittance, damping, wiggler, sextupole	3021
	J. Keil, I.V. Agapov, R. Brinkmann, X.N. Gavaldà, R. Wanzenberg DESY, Hamburg, Germany
	For the PETRA IV project at DESY it is planned to convert the 6 GeV synchrotron light source PETRA III into a diffraction limited storage ring with ultra-low emittances. PETRA IV should provide a natural emittance two orders of magnitude smaller as now. The energy and the current of 100 mA should be unchanged. Currently different lattice options are investigated to achieve an emittance in the range of 10-30 pm*rad. As one candidate for a lattice of PETRA IV a ring based on the concept of hybrid multi-bend achromats (HMBA) has been studied in detail. Due to the unique layout of PETRA III with long straight sections it is possible to use damping wigglers to reduce the emittance further. While this helps to mitigate intrabeam scattering it has the disadvantage of an increased energy spread. The linear and nonlinear parameters of this HMBA-based lattice and the influence of damping wigglers on beam parameters are discussed.
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THPAF045	Performance Optimisation of Turn-by-Turn Beam Position Monitor Data Harmonic Analysis	betatron, optics, software, electron	3064
	L. Malina, J.M. Coello de Portugal, J. Dilly, P.K. Skowroński, R. Tomás, M.S. Toplis CERN, Geneva, Switzerland J.M. Coello de Portugal UPC, Barcelona, Spain
	Nowadays, turn-by-turn beam position monitor data is increasingly utilized in many accelerators, as it allows for fast and simultaneous measurement of various optics parameters. The accurate harmonic analysis of turn-by-turn data costs beam time when needed online. Generally, the electronic noise is avoided by cleaning of the data based on singular value decomposition. In this paper, we exploit the cleaning procedure to compress the data for the harmonic analysis. This way the harmonic analysis is sped up by an order of magnitude. The impact on measurement accuracy is discussed.
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THPAF055	Space Charge Studies on LEIR	resonance, space-charge, emittance, simulation	3095
	Á. Saá Hernández, H. Bartosik, N. Biancacci, S. Hirlaender, A. Huschauer, D. Moreno Garcia CERN, Geneva, Switzerland
	The performance of the CERN Low Energy Ion Ring with electron cooled ion beams is presently limited by losses occurring once the beam has been captured in the RF buckets. An intense machine study program was started by the end of 2015 to mitigate the losses and improve the performance of the accelerator. The measurements pointed to the interplay of direct space charge forces and excited betatron resonances as the most plausible driving mechanism of these losses. In this paper, we present the systematic space-charge measurements performed in 2017 and compare them to space-charge tracking simulations based on an adaptive frozen potential.
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THPAF059	Ultra Compact Symplectic Scheme for Fast Multi-Particle Tracking	flattop, target, octupole, sextupole	3107
	K. Skoufaris, Y. Papaphilippou, D. Pellegrini CERN, Geneva, Switzerland
	A versatile symplectic integration scheme has been developed in order to produce simplified versions of non linear lattices, preserving fundamental non-linear properties such as the detuning with amplitude and energy, in addition to the linear transport. The method has been applied to the LHC and benchmarked against tracking simulations with Sixtrack. This reduced lattice is made available as a refined replacement of the simple rotation matrix often used in multi-particle studies requiring a fast beam transport routine.
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THPAF060	A Benchmark Study of a High Order Symplectic Integration Method With Only Positive Steps	quadrupole, sextupole, multipole, target	3111
	K. Skoufaris, Y. Papaphilippou CERN, Geneva, Switzerland J. Laskar IMCCE, Paris, France Ch. Skokos University of Cape Town, Cape Town, South Africa
	The symplectic integrators CSABA & CSBAB are used in order to calculate single particles dynamics in accelerators and storage rings. These integrators include only forward drift steps while being highly accurate. Their efficiency to describe various optical and dynamical quantities for main magnetic elements and non-linear lattices is calculated and compared with the efficiency of the splitting methods used in MAD-X - PTC.
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THPAF067	Effects of Synchrotron Motion on Nonlinear Integrable Optics	synchrotron, optics, coupling, betatron	3131
	S.D. Webb, N.M. Cook RadiaSoft LLC, Boulder, Colorado, USA J.S. Eldred Fermilab, Batavia, Illinois, USA
	Funding: This work was supported in part by the Department of Energy, Office of Science, Office of High Energy Physics under contract number DE-SC0011340. An integrable Rapid-Cycling Synchrotron (iRCS) has been proposed as a replacement for the Fermilab Booster to achieve multi-MW beam power for the Fermilab high-energy neutrino program.* The successful application of nonlinear integrable optics to proton synchrotrons requires careful examination of single-particle longitudinal effects, especially synchrotron motion. For example, synchrobetatron coupling may excite transverse resonances in the ring. We will use the Synergia code to simulate the effects of this synchrobetatron coupling on the iRCS design with nonlinear inserts. Our goal will be to identify new invariants in the presence of this coupling. Assuming the synchrotron tune is sufficiently small, we have identified one or more adiabatic invariants of the motion. These invariants suggest that integrable optics with synchrobetatron coupling retains integrability when averaged over a synchrotron period. * J. Eldred and A. Valishev, "Design Considerations for Proposed Fermilab Integrable RCS," arXiv 1703.00952 (2017).
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THPAF068	Suppression of Instabilities Generated by an Anti-Damper With a Nonlinear Magnetic Element in IOTA	simulation, experiment, optics, damping	3134
	E.G. Stern, J.F. Amundson, A. Macridin Fermilab, Batavia, Illinois, USA
	Funding: US Department of Energy The Integrable Optics Test Accelerator (IOTA) storage ring is being constructed at Fermilab as a testbed for new accelerator concepts. One important series of experiments tests the use of a novel nonlinear magnetic insert to damp coherent instabilities. To test the damping power of the ele- ment, an instability of desired strength may be intentionally excited with an anti-damper. We report on simulations of beam stabilization using the Synergia modeling framework over ranges of driving and damping strengths.
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THPAF070	Design of a One-Dimensional Sextupole Using Semi-Analytic Methods	sextupole, quadrupole, coupling, focusing	3140
	L. Gupta Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA S. Baturin Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA Y.K. Kim University of Chicago, Chicago, Illinois, USA S. Nagaitsev Fermilab, Batavia, Illinois, USA
	Funding: Work supported by the U.S. National Science Foundation under Award No. PHY-1549132, the Center for Bright Beams Sextupole magnets provide position-dependent momentum kicks and are tuned to provide the correct kicks to particles within a small acceptance region in phase space. Sextupoles are useful and even necessary in circular accelerators for chromaticity corrections. They are routinely used in most rings, i.e. CESR. Although sextupole magnets are necessary for particle energy corrections, they also have undesirable effects on dynamic aperture, especially because of their non-linear coupling term in the momentum kick. Studies of integrable systems suggest that there is an analytic way to create transport lattices with specific transfer matrices that limit the momentum kick to one dimension. A one-dimension sextupole is needed for chromaticity corrections: a horizontal sextupole for horizontal bending magnets. We know how to make a "composite" horizontal sextupole using regular 2D sextupoles and linear transfer matrices in an ideal thin-lens approximation. Thus, one could create an accelerator lattice using linear elements, in series with sextupole magnets to create a '1d sextupole'. This paper describes progress towards realizing a realistic focusing lattice resulting in a 1d sextupole.* *S.A. Antipov, et. al., Single-particle dynamics in a nonlinear accelerator lattice: attaining a large tune spread with octupoles in IOTA, Journal of Instrumentation, Volume 12, April 2017.
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THPAF071	McMillan Lens in a System with Space Charge	emittance, simulation, resonance, quadrupole	3143
	I. Lobach University of Chicago, Chicago, Illinois, USA S. Nagaitsev, E.G. Stern, T. Zolkin Fermilab, Batavia, Illinois, USA
	Space charge (SC) in a circulating beam in a ring produces both betatron tune shift and betatron tune spread. These effects make some particles move on to a machine resonance and become unstable. Linear elements of beam optics cannot reduce the tune spread induced by SC because of its intrinsic nonlinear nature. We investigate the possibility to mitigate it by a thin McMillan lens providing a nonlinear axially symmetric kick, which is qualitatively opposite to the accumulated kick by SC. Experimentally, the proposed concept can be tested in Fermilab's IOTA ring. A thin McMillan lens can be implemented by a short (70 cm) insertion of an electron beam with specifically chosen density distribution in transverse directions. In this article, to see if McMillan lenses reduce the tune spread induced by SC, we make several simulations with particle tracking code Synergia. We choose such beam and lattice parameters that tune spread is roughly 0.5 and a beam instability due to the half-integer resonance 0.5 is observed. Then, we try to reduce emittance growth by shifting betatron tunes by adjusting quadrupoles and reducing the tune spread by McMillan lenses.
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THPAF073	Beam Phase Space Tomography at Fast Electron Linac at Fermilab	experiment, coupling, MMI, linac	3146
	A.L. Romanov Fermilab, Batavia, Illinois, USA
	FAST linear accelerator has been commissioned in 2017. Experimental program of the facility requires high quality beams with well-defined properties. Solenoidal fields at photoinjector, laser spot shape, space charge forces and other effects can distort beam distribution and introduce coupling. This work presents results of a beam phase space tomography for a coupled 4D case. Beam was rotated in two planes with seven quads by 180 degrees and images from YaG screen were used to perform SVD based reconstruction of the beam distribution.
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THPAF075	Numerical Simulations of Space Charge Compensation with an Electron Lens	space-charge, electron, simulation, emittance	3154
	E.G. Stern, Y.I. Alexahin, J.F. Amundson, A.V. Burov, A. Macridin, V.D. Shiltsev Fermilab, Batavia, Illinois, USA
	The future high energy physics program at Fermilab requires that the proton complex operate with beam bunch intensities four times larger than is currently handled. At these intensities space charge nonlinear defocussing effects cause unacceptable particle losses especially in the low energy rapid-cycling-synchrotron (RCS) Booster. Focusing electron lens elements may offer a solution by providing partial space charge compensation but there is a need for detailed simulations as this technique has not been demonstrated. We report on high fidelity numerical 6D space charge simulations in a model accelerator lattice with a record high space charge tune shift approaching unity.
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THPAF084	Impact of RF Coupler Kicks on Beam Dynamics in BESSY VSR	cavity, simulation, kicker, SRF	3182
	T. Mertens Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany T. Atkinson, F. Glöckner, A. Jankowiak, M. Ries, A.V. Tsakanian HZB, Berlin, Germany
	The expected BESSY II upgrade to BESSY VSR requires the installation of a superconducting RF system, consisting of four cavities. Two cavities will operate at 1.5 GHz and two at 1.75 GHz. Each of them is equipped with a Fundamental Power Coupler and with Higher Order Mode (HOM) damping waveguide couplers. Dedicated simulations of these cavities and couplers have shown that at the location of the FPC the beam will see a transverse kick [], perturbing the closed orbit and affecting transverse beam dynamics. We present the results of simulations and experiments of the impact on transverse beam dynamics of these coupler induced kicks for different FPC orientations. [] Study on RF Coupler Kicks of SRF Cavities in the BESSY VSR Module A. Tsakanian#, H.-W. Glock, T. Mertens, M. Ries, A. Velez, J. Knobloch IPAC18
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THPAK008	Space Charge and Microbunching Studies for the Injection Arc of MESA	space-charge, bunching, simulation, injection	3221
	A. Khan, O. Boine-Frankenheim Institut Theorie Elektromagnetischer Felder, TU Darmstadt, Darmstadt, Germany C.P. Stoll IKP, Mainz, Germany
	For intense electron bunches traversing through bends, as for example the recirculation arcs of an ERL, space charge (SC) may result in beam phase space deterioration. SC modifies the electron transverse dynamics in dispersive regions along the beam line and causes emittance growth for mismatched beams or for specific phase advances. On the other hand, longitudinal space charge together with dispersion can lead to the microbunching instability. The present study focuses on the 180° low energy (5 MeV) injection arc lattice for the multi-turn Mainz Energy-recovering Superconducting Accelerator (MESA), which should deliver a CW beam at 10⁵ MeV for physics experiments with an internal target. We will discuss matching conditions with space charge together with the estimated microbunching gain for the arc. The implication for the ERL operation will be outlined, using 3D envelope and tracking simulations. Supported by the DFG through GRK 2128
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THPAK024	A new method to measure the Beta function in a Paul trap	dipole, experiment, emittance, resonance	3262
	L. Martin, S.L. Sheehy JAI, Oxford, United Kingdom K. Ito, H. Okamoto HU/AdSM, Higashi-Hiroshima, Japan D.J. Kelliher STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom S. Machida STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	The Simulator of Particle Orbit Dynamics (S-POD) is a linear Paul trap at Hiroshima University, Japan, used to study beam physics. S-POD has so far been used to study resonances in high intensity beams, predominantly using a simple alternating gradient lattice configuration. Recently a similar apparatus, the Intense Beam Experiment (IBEX), has been constructed at the Rutherford Appleton Lab in the UK. To use either of these experiments to study beam dynamics in more complex lattice configurations in the future further diagnostic techniques must be developed for Paul traps. Here we describe a new method to measure the beta function and emittance at a given time in a Paul trap.
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THPAK035	Numerical Tools for Modeling Nonlinear Integrable Optics in IOTA with Intense Space Charge Using the Code IMPACT-Z	space-charge, optics, simulation, proton	3290
	C.E. Mitchell, J. Qiang LBNL, Berkeley, California, USA
	Funding: This work is supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics. The Integrable Optics Test Accelerator (IOTA) is a novel storage ring under commissioning at Fermi National Accelerator Laboratory designed to investigate the dynamics of beams with large transverse tune spread in the presence of strongly nonlinear integrable optics. Several new numerical tools have been implemented in the code IMPACT-Z to allow for high-fidelity modeling of the IOTA ring during Phase II operation with intense proton beams. A primary goal is to ensure symplectic treatment of both single-particle and collective dynamics. We describe these tools and demonstrate their application to modeling nonlinear integrable dynamics with space charge in IOTA.
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THPAK036	Accurate Modeling of Fringe Field Effects on Nonlinear Integrable Optics in IOTA	optics, quadrupole, octupole, betatron	3294
	C.E. Mitchell, R.D. Ryne LBNL, Berkeley, California, USA F.H. O'Shea RadiaBeam, Santa Monica, California, USA
	Funding: This work is supported by the U.S. Department of Energy, Office of High Energy Physics. The Integrable Optics Test Accelerator (IOTA) is a novel storage ring under commissioning at Fermi National Accelerator Laboratory designed to investigate the dynamics of beams with large transverse tune spread in the presence of strongly nonlinear integrable optics. Uncontrolled nonlinear effects resulting from magnetic fringe fields can affect the integrability of particle motion, and long-term numerical tracking requires an accurate representation of these effects. Surface fitting algorithms provide a robust and reliable method for extracting this information from 3-dimensional magnetic field data provided on a grid. These algorithms are applied to investigate the unique nonlinear magnetic insert of the IOTA ring, and consequences of the fringe fields to the long-term dynamics of the beam are discussed.
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THPAK040	Bunched Beam Envelope Instability in a Periodic Focusing Channel	emittance, focusing, simulation, solenoid	3301
	J. Qiang LBNL, Berkeley, California, USA
	The space-charge driven envelope instability presents a great danger in high intensity accelerator design. In this paper, we report on the study of bunched beam envelope instability in a periodic focusing channel using three-dimensional envelope model for a 3D uniform Waterbag distribution and a 3D Gaussian distribution. Our results show that the envelope instability stopband becomes broader with the increase of longitudinal focusing and are not sensitive to the type of distribution. Self-consistent macroparticle simulations using both distributions show similar structure in emittance growth but also extra instability stopbands. The emittance growth from the Waterbag distribution has larger stopband than that from the Gaussian distribution.
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THPAK042	On Long-Term Space-Charge Tracking Simulation	space-charge, simulation, emittance, optics	3305
	J. Qiang LBNL, Berkeley, California, USA
	The nonlinear space-charge effects in high intensity accelerator can degrade beam quality and cause particle losses. Self-consistent macroparticle tracking simulations have been widely used to study these space-charge effects. However, it is computationally challenging for long-term tracking simulation of these effects. In this paper, we study a fully symplectic self-consistent particle-in-cell model and numerical methods to mitigate numerical emittance growth. We also discuss about a fast alternative frozen space-charge model that has a potential to improve computational speed significantly.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK042
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THPAK049	Simulation Code Design for the Interpreted Language Using the Compiled Module	simulation, interface, EPICS, linac	3327
	K. Fukushima, M.A. Davidsaver, Z.Q. He, M. Ikegami, G. Shen, T. Yoshimoto, T. Zhang FRIB, East Lansing, USA J. Qiang LBNL, Berkeley, California, USA
	Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DESC0000661. We are planning to use two types of the accelerator simulation codes for FRIB (Facility for Rare Isotope Beams). One is the linear envelope tracking code "FLAME" for fast simulations. FLAME can calculate the FRIB-linac beam envelope within an order of ms. This is useful in systematic surveys, wide range optimizations and so forth. This code, written in C++, was designed with Python interface from the beginning. On the other hand, "Advanced-IMPACT" is the particle tracking code dedicated for precise and realistic calculations, which can simulate the particle losses, nonlinear and space-charge effects. This code is refactored from the Fortran code IMPACT-Z developed in LBNL. Both codes provide the compiled modules for Python to support flexible inputs and direct outputs management in memory. In other words, they can be directly connected to the modern scientific tools through the Python interface without delay in the data transport. In addition, these modules can accomplish the interactive simulation processes without losing computational efficiency. We report the knowledges applicable for other accelerator simulation codes among those obtained through these developments and designs.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK049
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THPAK054	Optics Calibration and Measurement for Low Alpha Lattices in TPS Storage Ring	emittance, optics, coupling, operation	3343
	F.H. Tseng, C.H. Chen, J.Y. Chen, P.C. Chiu, C.H. Huang, C.-C. Kuo, C.C. Liang, C.Y. Liao, Y.-C. Liu, H.-J. Tsai NSRRC, Hsinchu, Taiwan
	In order to provide short-pulse radiation for pump-probe experiments and coherent radiation for THz/IR measurements, we develop low alpha lattices to reduce the momentum compaction factor from nominal operation values 2.410^-4 to 2.610-5 or lower. The corresponding bunch length at 2.8 MV RF voltage and zero current are from 10.78 ps to 3.55 ps or less. In the low alpha operations, the bunch lengthening as a function of bunch current, the orbit drift and noise enhancements as well as rf stability effect are observed. In this report we will present our studies on the lattice design, optics correction, beam parameters measurements and alpha measurements.
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THPAK063	Electron Beam Pattern Rotation as a Method of Tunable Bunch Train Generation	electron, laser, HOM, experiment	3372
	A. Halavanau, P. Piot Northern Illinois University, DeKalb, Illinois, USA P. Piot Fermilab, Batavia, Illinois, USA
	Transversely modulated electron beams can be formed in photo injectors via microlens array (MLA) UV laser shaping technique. Micro lenses can be arranged in polygonal lattices, with resulting transverse electron beam modulation mimicking the lenses pattern. Conventionally, square MLAs are used for UV laser beam shaping, and generated electron beam patterns form square beamlet arrays. The MLA setup can be placed on a rotational mount, thereby rotating electron beam distribution. In combination with transverse-to-longitudinal emittance exchange beam line, it allows to vary beamlets horizontal projection and tune electron bunch train. In this paper, we extend the technique to the case of different MLA lattice arrangements and explore the benefits of its rotational symmetries.
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THPAK064	Theoretical Modeling of Electromagnetic Field from Electron Bunches in Periodic Wire Medium	radiation, simulation, electron, FEL	3376
	S.S. Chuchurka, A.I. Benediktovitch BSU, Minsk, Belarus, Belarus S.N. Galyamin, V.V. Vorobev Saint Petersburg State University, Saint Petersburg, Russia A. Halavanau Northern Illinois University, DeKalb, Illinois, USA
	Funding: Work supported by the Grant from Russian Foundation for Basic Research (No. 17-52-04107). The interaction of relativistic electrons with periodic structures results in radiation by a number of mechanisms. In case of crystals one obtains parametric X-ray radiation, its frequency is determined by distance between crystallographic planes and direction of electron beam. If instead of crystal one considers a periodic structure of metallic wires with period of the order of mm, one can expect emission of THz radiation. In the present contribution we consider theoretical approaches for modeling of the distribution of electromagnetic field from electron bunches in lattice formed by metallic wires. The analytical description is possible for the case of wires with small radius, the range of validity is checked by numerical simulations. The intensity of radiation will be significantly increased if the electrons in the bunch could radiate coherently. Two possibilities will be discussed: the prebunching of the beam and the self-modulation of the beam due to interaction with radiated field.
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THPAK082	Simulation of Perturbative Effects in IOTA	simulation, optics, octupole, emittance	3422
	C.C. Hall, D.L. Bruhwiler, N.M. Cook, J.P. Edelen, S.D. Webb RadiaSoft LLC, Boulder, Colorado, USA
	The Integrable Optics Test Accelerator (IOTA) is being commissioned at Fermi National Laboratory for study of the concept of nonlinear integrable optics. The use of a special nonlinear magnetic element introduces large tune spread with amplitude while constraining the idealized dynamics by two integrals of motion. The nonlinear element should provide suppression of instabilities through nonlinear decoherence. We examine the case of a bunch injected off-axis and the resulting damping of centroid oscillations from decoherence. A simple model of the damping is described and compared to simulation.
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THPAK085	3D Space Charge in Bmad	space-charge, simulation, software, brightness	3428
	C.E. Mayes SLAC, Menlo Park, California, USA R.D. Ryne LBNL, Berkeley, California, USA D. Sagan Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	We present a parallel fast Fourier transform based 3D space charge software library based on integrated Green functions. The library is open-source, and has been structured to easily be used by existing beam dynamics codes. We demonstrate this by incorporating it with the Bmad toolkit for charged particle simulation, and compare with analytical formulas and well-established space charge codes.
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THPAK108	Fourier Coefficients of Long-Range Beam-Beam Hamiltonian via Two-Dimensional Bessel functions	resonance, optics, emittance, TRIUMF	3486
	D. Kaltchev TRIUMF, Vancouver, Canada
	The two-dimensional coefficients (resonance basis) in the Fourier expansion of the long-range beam-beam Hamiltonian have been expressed through the (less familiar) generalized modified Bessel functions of two arguments. We describe an efficient method to compute these coefficients based on the above representation. The method has been applied to HL-LHC lattices and benchmarked against MadX simulations of detuning.
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THPAK126	Revised Optics Design for the JLEIC Ion Booster	booster, sextupole, injection, betatron	3537
	E.W. Nissen, T. Satogata JLab, Newport News, Virginia, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177. We outline the recently redesigned booster for the pro-posed Jefferson Lab Electron Ion Collider (JLEIC). This booster will inject protons (or ions of equivalent rigidity) at 280 MeV and accelerate them to 8 GeV kinetic energy. To avoid transition crossing, the booster uses flexible momentum compaction (FMC) lattices to raise the transi-tion gamma above the reach of the machine. We also include several families of sextupoles to simultaneously control the chromaticities, and nonlinear dispersions that were excited by the FMC cells.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK126

Paper

Title

Other Keywords

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MOZGBF5

Analysis of Polarization Decay at RHIC Store

polarization, resonance, emittance, target

76

H. Huang, P. Adams, E.C. Aschenauer, A. Poblaguev, W.B. Schmidke
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
There are polarization losses in RHIC store due to various sources, such as emittance growth and higher order spin resonances. The beam polarization was measured several times over a store by the p-carbon polarimeters situated in both rings. These provide information on the polarization decay over time and also polarization profile development over time. A polarized jet was also used to monitor the polarization continuously through store, though with limited statistical accuracy. These polarization measurements and emittance measurements from the IPM are analyzed and the polarization loss from different sources are reviewed.

Slides MOZGBF5 [4.526 MB]

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MOPMF014

Polarization at eRHIC Electron Storage Ring, an Ergodic Approach

polarization, electron, simulation, storage-ring

112

F. Méot
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Based on considerations of ergodicity of the dynamical system of an electron bunch at equilibrium, the preservation of polarization in an electron storage ring is estimated from the tracking of a very limited number of electrons. This has a substantial impact on required High Power Computing resources, in noticeable contrast with the method generally used that tracks tens of electron bunches, each comprised of thousands of particles, for several thousands of turns. It is also shown that a minimum number of tracking turns is required in order to ensure the numerical convergence of the linear regressions that yield depolarizing time constant values from tracking, in both methods.

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MOPMF016

Progress on RCS eRHIC Injector Design

resonance, polarization, emittance, detector

115

V.H. Ranjbar, M. Blaskiewicz, J.M. Brennan, S.J. Brooks, D.M. Gassner, H.-C. Hseuh, I. Marneris, F. Méot, M.G. Minty, C. Montag, V. Ptitsyn, K.S. Smith, S. Tepikian, F.J. Willeke, H. Witte, B. P. Xiao, A. Zaltsman
BNL, Upton, Long Island, New York, USA
I.V. Pogorelov
Tech-X, Boulder, Colorado, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
We have refined the design for the Rapid Cycling Synchrotron (RCS) polarized electron injector for eRHIC. The newer design includes bypasses for the eRHIC detectors and definition of the lattice layout in the existing RHIC tunnel. Additionally, we provide more details on the RF, alignment and orbit control, and magnet specifications.

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MOPMF021

Ground Motion Measurement and Analysis for HEPS

ground-motion, site, emittance, ion-source

125

F. Yan, Z. Duan, D. Ji, Y. Jiao, Z.Z. Wang, Y. Wei, G. Xu
IHEP, Beijing, People's Republic of China

HEPS have very challenging beam stability require-ments. Special cares are mandatory in developing site vibration specifications, stable building design concepts, and passive and active ways to minimize effects on the stability of the photon beam and critical accelerator and beamline components caused by ambient ground motion sources. However, among all these work, reasonable as-sessment of the vibration induced beam instability has to be the first step. This paper will focuses on the measure-ment results of the ground motion on HEPS site, the es-tablishment of reasonable beam dynamic models, the influences of ground motion to the beam of main ring.

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MOPMF028

A Superconvergent Algorithm for Invariant Spin Field Stroboscopic Calculations

simulation, resonance, polarization, storage-ring

145

D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: National Science Foundation and the Department of Energy
Stroboscopic averaging can be used to calculate the invariant spin field \bfn for particles with a finite oscillation amplitude in phase space. The standard technique starts with making a guess for \bfn(\bfr), which is a function of the phase space position \bfr. By tracking a particle's orbital position forward in time and then projecting the guessed \bfn backwards to the starting phase space point, the average of the backward projected spins will converge to the invariant spin direction linearly as 1/N where N is the number of turns tracked. The convergence can be accelerated by an iterative method that uses an approximate invariant spin field constructed by averaging the calculated spin field over points that are close in orbital phase space. This superconvergent algorithm has been built into a new program based upon the Bmad toolkit for charged particle and X-ray simulations.

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MOPMF067

Optimized Arc Optics for the HE-LHC

dipole, injection, sextupole, optics

277

Y.M. Nosochkov, Y. Cai
SLAC, Menlo Park, California, USA
M.P. Crouch, M. Giovannozzi, M. Hofer, J. Keintzel, T. Risselada, E. Todesco, R. Tomás, F. Zimmermann
CERN, Geneva, Switzerland
D. Zhou
KEK, Ibaraki, Japan
L. van Riesen-Haupt
JAI, Oxford, United Kingdom

Funding: Work supported by the European Commission under Capacities 7th Framework Programme project EuCARD-2, grant agreement 312453, and the HORIZON 2020 project EuroCirCol, grant agreement 654305.
The High Energy LHC (HE-LHC) proton-proton collider is a proposed replacement of the LHC in the existing 27-km tunnel, with the goal of reaching the centre-of-mass beam energy of 27 TeV. The required higher dipole field can be realized by using 16-T dipoles being developed for the FCC-hh design. A major concern is the dynamic aperture at injection energy due to degraded field quality of the new dipole based on Nb3Sn superconductor, the potentially large energy swing between injection and collision, and the slightly reduced magnet aperture. Another issue is the field in quadrupoles and sextupoles at top energy, for which it may be cost-effective, wherever possible, to stay with Nb-Ti technology. In this study, we explore design options differed by arc lattice, for three choices of injection energy, with the goal of attaining acceptable magnet field and maximum injection dynamic aperture with dipole non-linear field errors.

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MOPMF079

The CEPC lattice design with combined dipole magnet

sextupole, dipole, collider, dynamic-aperture

315

D. Wang, S. Bai, F.S. Chen, W. Chou, J. Gao, Y.M. Peng, Y. Wang, M. Yang, C.H. Yu, Y. Zhang
IHEP, Beijing, People's Republic of China

For the lattice of CEPC collider ring, the combined magnet (dipole+sextupole) scheme has been developed to reduce the power consumption of the stand-alone sextu-poles. The power consumption of sextupoles has been decreased by 75% due to 50% reduction of strength. The dynamic aperture for the combined magnet scheme is as good as the original lattice. The magnet design for this kind of combined dipole has been done which provides a good support for this new idea.

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MOPMK002

Integrated Full HE-LHC Optics and Its Performance

dipole, injection, insertion, target

348

M. Hofer
TU Vienna, Wien, Austria
M.P. Crouch, J. Keintzel, T. Risselada, R. Tomás, F. Zimmermann
CERN, Geneva, Switzerland
Y.M. Nosochkov
SLAC, Menlo Park, California, USA
D. Zhou
KEK, Ibaraki, Japan
L. van Riesen-Haupt
JAI, Oxford, United Kingdom

One possible future hadron collider design investigated in the framework of the Future Circular Collider (FCC) study is the High-Energy LHC (HE-LHC). Using the 16 T dipoles developed for the FCC-hh the center of mass energy of the LHC is set to increase to 27 TeV. To achieve this set energy goal, a new optics design is required, taking into account the constraint from the LHC tunnel geometry. In this paper, two different lattices for the HE-LHC are presented. Initial considerations take into account the physical aperture at the proposed injection energy as well as the energy reach of these lattices. The dynamic aperture at the injection energies is determined using latest evaluations of the field quality of the main dipoles.

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MOPMK014

Resistive-Wall Impedance of Insertions for FCC-hh

impedance, insertion, optics, experiment

378

B. Riemann, S. Khan
DELTA, Dortmund, Germany
S. Arsenyev, D. Schulte
CERN, Geneva, Switzerland

Funding: This work is supported by the German Ministry of Education & Research (BMBF, funding code 05P15PERB1) and CERN (reference numbers KE3123, EDMS 1606722).
In this work, transverse and longitudinal resistive-wall impedances for beam pipes in the experiment, injection, extraction and RF systems insertion regions of the Future Hadron-Hadron Collider (FCC-hh) are computed based on contributions from different given cross sections of the surrounding (elliptical) chamber parts along the beam path, their temperature-dependent conductivities, and optical functions. An emphasis is placed on the behaviour of transverse impedance in the main experimental regions (A and G), where maximum beta values of 10⁴ to 10⁵ m occur in dependence of the operation mode respectively lattice configuration. Main contributions to the transverse and longitudinal impedance budget are identified, and possibilities of reducing them are discussed.

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MOPML008

JLEIC Electron Ring Dynamic Aperture with Non-linear Field Errors

dynamic-aperture, electron, emittance, sextupole

404

Y.M. Nosochkov, Y. Cai
SLAC, Menlo Park, California, USA
F. Lin, V.S. Morozov, G.H. Wei, Y. Zhang
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under US DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357. Work supported by the US DOE Contract DE-AC02-76SF00515.
We present results of dynamic aperture study for the updated electron ring lattice of the Jefferson Lab Electron-Ion Collider (JLEIC). The lattice design features low emittance arcs with local compensation of sextupole non-linear effects, and low emittance non-linear chromaticity correction sections. Dynamic aperture tracking simulations are performed to evaluate the effects of non-linear field errors, the sensitivity to betatron tune, and the impact of momentum error. Dynamic aperture is also evaluated with the measured PEP-II field errors. Preliminary tolerances to the non-linear field errors in the Final Focus quadrupoles are estimated.

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MOPML010

Challenges and Status of Tuning Simulations for CLIC Traditional Beam Delivery System

luminosity, linear-collider, collider, simulation

412

R.M. Bodenstein, P. Burrows
JAI, Oxford, United Kingdom
E. Marín
CERN, Geneva, Switzerland

The beam delivery system (BDS) for the 3 TeV version of the Compact Linear Collider (CLIC) has two main design types. One type is referred to as the local scheme, as it is approximately one kilometer shorter and corrects the chromaticity in both planes. The other type is referred to as the traditional scheme, and separates the chromaticity correction of each plane into different areas. The expectation early in the studies was that the traditional scheme would be easier to tune. This work will address the problems experienced in tuning simulations for the traditional BDS and describe the current state of these simulations.

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MOPML061

Hadron Therapy Machine Simulations Using BDSIM

simulation, hadron, hadrontherapy, proton

546

W. Shields
JAI, Egham, Surrey, United Kingdom
S.T. Boogert, L.J. Nevay
Royal Holloway, University of London, Surrey, United Kingdom
J. Snuverink
PSI, Villigen PSI, Switzerland

Minimising the background radiation dose in hadron therapy from particle losses and secondary emissions is of the highest importance for patient protection. To achieve this, tracking particles from source to the patient delivery region in a single simulation provides a quantitative description that distinguishes the background radiation from the treatment dose arriving at the gantry's isocentre. We demonstrate the ability to simulate beam transport, particle loss studies, and background radiation tracking in an example hadron therapy machine using BDSIM, a Geant4 based Monte Carlo simulation code for tracking high energy particles within a particle accelerator and its surrounding environment. Machine optics verification is also demonstrated through comparison to existing accelerator tracking codes.

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TUPAF073

Simulation of Integrable Synchrotron with Space-charge and Chromatic Tune-shifts

space-charge, simulation, optics, synchrotron

894

J.S. Eldred, A. Valishev
Fermilab, Batavia, Illinois, USA

We present a nonlinear rapid-cycling synchrotron designed as a high-intensity replacement of the Fermilab Booster. The design incorporates integrable optics, an innovation in particle accelerator design that enables strong nonlinear focusing without generating parametric resonances. We use the Synergia space-charge tracking code to demonstrate the stability of a beam in this lattice with a space-charge tune-shift up to 0.4 and a rms momentum spread up to 0.4\%. We demonstrate the benefit of increased lattice periodicity.

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TUPAL027

Design of Multi-MW Rapid Cycling Synchrotron for Accelerator Driven Transmutation System

extraction, acceleration, proton, synchrotron

1057

Y. Fuwa
Kyoto ICR, Uji, Kyoto, Japan
N. Amemiya
Kyoto University, Kyoto, Japan
Y. Ishi, Y. Kuriyama, T. Uesugi
Kyoto University, Research Reactor Institute, Osaka, Japan

For the practical application of Accelerator Driven System (ADS) that reduces the harmfulness of radioactive waste by transmutation, we are studying the development of a compact accelerator using a synchrotron as an accelerator capable of supplying a stable proton beam to a nuclear reactor. In this plan, we aim to realize down-sizing and high reliability by adopting an alternating high temperature superconducting magnet and a high repetition synchrotron applying resonant beam extraction. In this presentation we report the basic design of the optical system and beam acceleration sequence of this synchrotron.

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TUPAL058

Studies for Major ISIS Upgrades via Conventional RCS and Accumulator Ring Designs

injection, simulation, space-charge, emittance

1148

C.M. Warsop, D.J. Adams, H.V. Cavanagh, P.T. Griffin-Hicks, B. Jones, B.G. Pine, R.E. Williamson
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

ISIS is the spallation neutron source at the Rutherford Appleton Laboratory in the UK, which provides 0.2 MW of beam power via a 50 Hz, 800 MeV proton RCS. Detailed studies are now under way to find the optimal configuration for a next generation, short pulsed neutron source that will define a major ISIS upgrade in ~2031. Accelerator configurations being considered for the MW beam powers required include designs exploiting FFAG rings as well as conventional accumulator and synchrotron rings. This paper describes work exploring the latter, conventional options, but includes the possibility of pushing further toward intensity limits to reduce facility costs. The scope of planned studies is summarised, looking at optimal exploitation of existing ISIS infrastructure, and incorporating results from recent target studies and user consultations. Results from initial baseline studies for an accumulator ring and RCS located in the existing ISIS synchrotron hall are presented. Injection scheme, foil limits, longitudinal and transverse beam dynamics optimization with related beam loss and activation are outlined, as are results from detailed 3D PIC simulations.

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TUPAL064

Extended-Domain Tune-Scans for the HL-LHC Dynamic Aperture in Presence of Beam-Beam Effects

resonance, octupole, dynamic-aperture, beam-beam-effects

1163

D. Kaltchev
TRIUMF, Vancouver, Canada
N. Karastathis, Y. Papaphilippou, D. Pellegrini
CERN, Geneva, Switzerland

We report simulations of the HL-LHC dynamic aperture (DA) at collision energy in the presence of beam-beam effects (weak-strong approximation) aiming to determine its dependence on the working point in tune space. Both linear domains working points are explored, spanning over (0.028 – 0.33) in horizontal tune, and two-dimensional ones which focus on more promising sub-regions near the diagonal. The range of parameters, such as bunch intensity and emittance, are chosen to correspond to the more important HL-LHC scenarios. A comparison with the LHC as built is also made. Direct benefit from these studies is the possible identification of working points alternative to the nominal one (in terms of dynamic aperture). They also help to understand the dependence of DA on particular resonance lines present in the vicinity of the footprint. In this work, the necessary resources were provided by the LHC@home project, based on the BOINC-SixTrack platform for distributed Computing.

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TUPMF011

Calculation of Expected Orbit Motion Due to Girder Resonant Vibration at the APS Upgrade

ground-motion, factory, resonance, quadrupole

1269

V. Sajaev, Z. Liu, J. Nudell, C.A. Preissner
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The Advanced Photon Source (APS) is pursuing an upgrade to the storage ring that will provide electron beam with extremely low emittance. To allow users to take advantage of this small beam size, the beam orbit motion has to be kept stable to within a fraction of the beam size. To keep the beam orbit stable on a sub-micron level, one needs to carefully design magnet supports/girders so that the ground motion does not lead to excessive orbit motion due to resonant modes of magnet supports. In this paper, we will describe the process of calculating the expected orbit motion due to girder resonant vibration. First, we will present the simulation results for the girder resonant modes, then we will calculate the orbit amplification factors for the girder deformation modes, then calculate the expected orbit motion using measured ground motion spectrum. This process can be used to evaluate the design of the magnet supports.

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TUPMF012

Determination of the Ground Motion Orbit Amplification Factors Dependence on the Frequency for the APS Upgrade Storage Ring

ground-motion, factory, storage-ring, simulation

1272

V. Sajaev, C.A. Preissner
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The Advanced Photon Source (APS) is pursuing an upgrade to the storage ring that will provide electron beam with extremely low emittance. To allow users to take advantage of this small beam size, the beam orbit motion has to be kept stable to within a fraction of the beam size, which translates to sub-micron orbit stability requirement. Ground motion provides significant contribution to the overall expected beam motion, especially at lower frequencies where the ground motion has larger amplitudes. At the same time, the lattice amplification factors reduce when the ground motion becomes coherent at low frequencies. In this paper, we will present simulation of the lattice amplification factor dependence on the ground motion coherence length and show results of the ground motion coherence measurements at APS. After that, we will determine the lattice amplification factors dependence on the ground motion frequency, that can be used to calculate the expected effect of the ground motion on the orbit stability.

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TUPMF013

Optimizations of Nonlinear Beam Dynamics Performance on APS-U Lattice

MMI, sextupole, multipole, storage-ring

1276

Y.P. Sun, M. Borland
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
For next-generation storage ring light sources, such as the Advanced Photon Source (APS) Multi-Bend Achromat (MBA) upgrade, the strong nonlinearities introduced by the strong chromaticity sextupoles plus the small physical apertures make it challenging to achieve large dynamic acceptance (DA) and long Touschek lifetime, even when using the on-axis swap-out injection scheme. Several different methods have been explored for nonlinear dynamics optimization. The optimization objectives variously include the chromaticities up to third order, resonance driving and detuning terms, on- and off-momentum dynamic acceptance, chromatic and geometric tune footprint, local momentum acceptance (LMA), variation of betatron oscillation invariant, Touschek lifetime, etc. In addition, optimization can be performed without errors, with selected random errors, and with sets of errors that reflect post-commissioning conditions. In this paper, these different optimization methods are compared for the nonlinear beam dynamics performance of the Advanced Photon Source upgrade (APS-U) lattice, in terms of the dynamic acceptance, local momentum acceptance, and other performance measures. The impact from different error sources is also studied.

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TUPMF035

First Demonstration of the Transparent Fast-to-slow Corrector Current Shift in the NSLS-II Storage Ring

feedback, experiment, operation, photon

1323

X. Yang, V.V. Smaluk, Y. Tian, L. Yu
BNL, Upton, Long Island, New York, USA

To realize the full benefits of the high brightness and ultra-small beam sizes of NSLS-II, it is essential that the photon beams are exceedingly stable (a level of 10% beam size). In the circumstances of implementing local bumps, changing ID gaps, and long-term drifting, the fast orbit feedback (FOFB) requires shifting the fast corrector strengths to the slow correctors to prevent the fast corrector saturation and to make the beam orbit stable in the sub-micron level. As the result, a reliable and precise technique of fast-to-slow corrector strength shift has been developed and tested at NSLS-II. This technique is based on the fast corrector response to the slow corrector change when the FOFB is on. In this article, the shift technique is described and the result of proof-of-principle experiment carried out at NSLS-II is presented. The maximum fast corrector current was reduced from greater than 0.45 A to less than 0.04 A with the orbit perturbation within ±1 μm. Especially when the step size of the shift was below 0.012 A, the amount of noise being added to the beam was none.

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TUPMF038

Design Considerations for an Ultralow Emittance Storage Ring for the Canadian Light Source

emittance, sextupole, quadrupole, electron

1334

L.O. Dallin
CLS, Saskatoon, Saskatchewan, Canada

Demands from light source scientists for more brilliant xray beams have resulted in the emergence of 4th generation storage rings. These demands include photon beams that are highly focussed and beams with high transverse coherence. Both these requirements are achieved with ultralow electron beam emittance. The practical development of the multi-bend achromat (MBA) concept by MAX IV has spurred many synchrotron light sources around the world to develop similar machines. For existing facilities two options are available: upgrading existing machines or building a new structure. The Canadian Light Source (CLS) has explored both options and has determined a new storage ring is required. Several design options for a 3.0 GeV ring have been developed. Best results are achieved when tracking is used to optimize the phase advance through the MBA structure to reduce the impact of the sextupoles on the dynamic aperture. Structures where no geometric sextupoles are required have been achieved while producing ultralow emittances.

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TUPMF049

Evolution of the Lattice Design for the High Energy Photon Source

emittance, storage-ring, injection, photon

1363

G. Xu, S.Y. Chen, Y. Jiao, J.L. Li, Y.M. Peng, Q. Qin, J.Q. Wang, C.H. Yu
IHEP, Beijing, People's Republic of China

The High Energy Photon Source (HEPS) is a high-energy, ultralow-emittance, kilometer-scale storage ring light source to be built in China. The HEPS lattice design has been started since 2008. In this paper we will review the evolution of the HEPS lattice design over the past ten years, focusing mainly on the linear optics design and nonlinear optimization.

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TUPMF050

DA Optimization Experiences in the Heps Lattice Design

sextupole, emittance, photon, storage-ring

1367

Y. Jiao, G. Xu
IHEP, Beijing, People's Republic of China

In the past decade, the so-called diffraction-limited storage ring (DLSR) light sources were proposed, promising much better radiation performance than available in the existing third generation light sources. Regarding the very strong focusing and chromatic sextupoles that required for reaching an ultralow emittance, to optimize the nonlinear dynamics and achieve an adequate dynamic aperture is an important topic in a DLSR design. In this paper we will present some tips distilled from the DA optimization experience of the High Energy Photon Source over the past ten years, hoping it could provide some aids to other ultralow-emittance designs.

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TUPMF052

Progress of Lattice Design and Physics Studies on the High Energy Photon Source

booster, storage-ring, injection, emittance

1375

G. Xu, X. Cui, Z. Duan, Z. Duan, Y.Y. Guo, D. Ji, Y. Jiao, J.L. Li, X.Y. Li, C. Meng, Y.M. Peng, Q. Qin, S.K. Tian, J.Q. Wang, N. Wang, Y. Wei, H.S. Xu, F. Yan, C.H. Yu, Y.L. Zhao
IHEP, Beijing, People's Republic of China

The High Energy Photon Source (HEPS) is an ultralow-emittance, kilometer-scale storage ring light source to be built in China. In this paper we will introduce the progress of the physical design and studies on HEPS over the past one year, covering issues of storage lattice design and optimization, booster design, injection design, collective effects, error study, insertion device effects, beam lifetime, etc.

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TUPMF054

Performance Comparison of Different Ultralow Emittance Unit Cells

emittance, dipole, storage-ring, quadrupole

1382

Y. Jiao, X.Y. Li, G. Xu
IHEP, Beijing, People's Republic of China

The available minimum emittance of a storage ring and the ring performance is closely related to the unit cell of the lattice. Up to now, several ultralow-emittance unit cells have been proposed and applied in the lattice design of the diffraction-limited storage ring light sources. In this study we quantitatively compared the performance of three typical unit cells, based on mainly the parameters of the High Energy Photon Source. The results indicate that the modified-TME unit cell with antibend and longitudinal gradient dipole allows the lowest possible emittance, given a long enough cell length.

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TUPMF056

Brightness Dependence Investigation and Optimizaiton for the Heps

brightness, emittance, photon, undulator

1390

Y. Jiao, M. Li, X.Y. Li
IHEP, Beijing, People's Republic of China

The High Energy Photon Source (HEPS) is an ultralow-emittance, kilometer-scale storage ring light source to be built in China. To maximize the photon spectral brightness, one of the most important performance parameters of the light source, we investigated the dependence of brightness on different parameters, such as the natural emittance, coupling, beta functions of the undulator section, and length of the undulator section. Based on this study, we optimized the HEPS lattice by using brightness as an optimizing objective.

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TUPMF059

Error Study of HEPS Booster

closed-orbit, booster, multipole, simulation

1398

C. Meng, D. Ji, J.L. Li, Y.M. Peng
IHEP, Beijing, People's Republic of China

The High Energy Photon Source (HEPS) is a 6-GeV, ultralow-emittance light source to be built in China. The injector is composed of a 500-MeV linac and a full energy booster with 1 Hz repetition frequency. The detailed error study of the booster will be presented, including misalignment errors and closed orbit correc-tion, magnetic field errors and power supply errors. The effect of errors on closed orbit, tune, chromaticity and dynamic aperture will be discussed. The dynamic aperture with multipole errors will be presented also.

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TUPMF060

Design of Bunch Lengthening System in Electron Linac

linac, booster, photon, bunching

1401

C. Meng, Y. Jiao, J.L. Li, S. Pei, Y.M. Peng, H.S. Xu
IHEP, Beijing, People's Republic of China

The High Energy Photon Source (HEPS) is a 6-GeV, ultralow-emittance light source to be built in China. The injector is composed of a linac and a full energy booster. To increase the threshold of TMCI in the booster, the HEPS linac design has been evolved with several iterations. The important middle-version design is a 300 MeV linac with rms bunch length larger than 20 ps. One bunch lengthening system is proposed and discussed in this paper.

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TUPMF062

Status of HEPS Booster Lattice Design and Physics Studies

booster, injection, storage-ring, extraction

1407

Y.M. Peng, Z. Duan, Y.Y. Guo, D. Ji, Y. Jiao, J.L. Li, C. Meng, S.K. Tian, H.S. Xu
IHEP, Beijing, People's Republic of China

The High Energy Photon Source (HEPS) with an ul-tralow emittance is proposed to be built in Beijing, Chi-na. It will utilize a booster as its full energy injector. On-axis swap-out injection is chosen as the baseline injec-tion scheme for the storage ring. As required by the stor-age ring, a beam with a bunch charge up to 2.5 nC is needed to be injected in the booster. However, limited by the transverse mode coupling instability (TMCI), such a high bunch charge is challenging. To overcome this problem, a lattice with a considerable large momentum compaction factor is designed. This paper reports the lattice design and physics studies of the HEPS booster, including injection and extraction design, error studies, eddy current effects, collective effects, and so on.

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TUPMF063

The Considerations of Improving TMCI Threshhold on HEPS Booster

booster, linac, storage-ring, injection

1411

Y.M. Peng, J.L. Li, C. Meng, S. Pei, H.S. Xu
IHEP, Beijing, People's Republic of China

The High Energy Photon Source (HEPS) is proposed in Beijing, China. The on-axis swap-out injection scheme will be used in the storage ring mainly because of the small dynamic aperture. Therefore, the booster needs to store more than 2.5 nC bunch charge. Under this requirement, the transverse mode coupling instability (TMCI) at the injection energy becomes the bunch charge restriction in the booster. Several changes in booster and linac for improving bunch charge threshold limited by TMCI are considered. The details will be expressed in this paper.

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TUPMF068

Beam Dynamics on a Coupling Resonance at PETRA III

resonance, coupling, optics, injection

1417

I.V. Agapov, J. Keil, G. Kube, G.K. Sahoo, R. Wanzenberg
DESY, Hamburg, Germany
Y.-C. Chae
ANL, Argonne, Illinois, USA
A.I. Novokshonov
TPU, Tomsk, Russia

Working on a coupling resonance is a usual way of producing round beams in a synchrotron. The beam dynamics in this regime is however more complicated, and the emittance is sensitive to the working point, coupling correction, and bunch current drop with time, which complicates the operation. We present experience with optics setup for working on a coupling resonance in PETRA III, including linear and nonlinear beam optics characteristics, and the measurement of the horizontal and vertical beam emittances with a 2D interferometer. Beam dynamics on a coupling resonance for PETRA IV, the MBA upgrade of PETRA III currently under consideration, is also presented.

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TUPMF071

Status of Impedance Modeling for the PETRA IV

impedance, wakefield, synchrotron, status

1423

Y.-C. Chae, R. Wanzenberg
DESY, Hamburg, Germany

The diffraction limited synchrotron light source envisioned for the PETRA IV project will require strong focusing to produce the small emittances in both planes. The large natural chromaticity together with small dispersion will require very strong sextupoles. In order to cope with high gradient magnets the radius of vacuum chamber tends to be in the range of 10 mm, which is very small compared to the current 40-mm wide elliptic chamber. The impedance element in the PETRA III was scaled down to fit into the smaller aperture so that the short range wakepotential can be computed numerically. For instance the beam position monitor (BPM) was reduced to 60% in dimension so that it can be used in PETRA IV. Even if the actual design of hardware does not exist yet, we assume that generic feature of PETRA III model is still valid. In this paper we report the up-to-date information on impedance model of PETRA IV together with the preliminary impedance budget based on the analytical formula. We also report the specific studies carried out to understand the kickfactor scaling with the chamber aperture whose radius is in the range of 8-12 mm.

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TUPMF073

Impedance Optimization of Small Gap Chambers for the High Single Bunch Current Operation at the Undulator Based Light Sources

impedance, undulator, ECR, simulation

1430

Y.-C. Chae
DESY, Hamburg, Germany

In the undulator based light sources the intensity limit of single bunch is often determined by the strong vertical instability caused by the wakefield in the ring, where the undulator itself is large impedance source. The optimization of transition from the large aperture to undulator's small-gap chamber is on-going research topic in an effort to reduce the vertical impedance; at the same time, the demand on single-bunch current is high from the timing-mode x-ray user community. In this paper, after showing the results obtained by exploring the parameter space guided by Stupakov's formula, we propose the linearly-segmented transition which can reduce the impedance down to 60% or less of the original linear taper. The reduction can be utilized either to increase the bunch current substantially or to install a smaller gap chamber without impacting the bunch current limit. For the definite result we considered the transition between two ellipses, namely, (a, b) = (42 mm, 21 mm) and (18 mm, 4 mm) over the length 15-30 cm in beam direction.

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TUPMF074

Control of Collective Effects by Active Harmonic Cavity in an MBA-based Light Source with Application to the PETRA Upgrade

cavity, impedance, emittance, synchrotron

1433

Y.-C. Chae, J. Keil
DESY, Hamburg, Germany

Based on the reference lattice for PETRA IV* we investigated collective effects with non-zero current. Out of many possibilities we firstly computed the intrabeam-scattering (IBS) effects on the emittance as well as lifetime as a function of current. The result indicated that PETRA IV would benefit from the reduced peak current when the harmonic cavity lengthens the bunch. The operating point of harmonic cavity was explored by tracking simulations as well as analytic formula. In order to compute the energy spread and bunch length we had used the known impedance function of the APS**. In this way more realistic estimation of IBS effects was expected. However, because of the complex nature of PETRA IV lattice, which includes achromatic cells for undulators, arc cells of octants and straight sectors for damping wigglers, we simplify the longitudinal dynamics by assuming the ring made of 92 multi-bend-achromat (MBA) cells. The optics is approximated as a linear-chromatic transfer map enabling fast tracking and the ring impedance is concatenated into the one location. The detailed collective effects with and without harmonic cavities are presented in the paper.
* J. Keil, "A PETRA IV Lattice Based on Hybrid Seven Bend Achromats", these proceedings.
** Y.-C. Chae and Y. Wang, "Impedance Database II for the Advanced Photon Source Storage Ring", Proc. PAC2007.

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TUPMF075

Lattice Studies of a Booster Synchrotron for PETRA IV

emittance, booster, damping, optics

1436

H.C. Chao
DESY, Hamburg, Germany

Associated with an upgrade study of the PETRA III light source toward ultra low-emittance is an upgrade study of the booster synchrotron. One possible solution obtained from a scaling of the ALBA booster to a circumference of 300 m is considered. It is based on a modified FODO lattice with combined function magnets and achromat straights. In this paper a method utilizing piecewise matchings supervised and optimized with evolutionary algorithm (PMSOEA) was devised to search the lattice. Some preliminary results are shown and discussed.

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TUPMK003

Advances in the Sirius Delta-Type Undulator Project

undulator, polarization, storage-ring, MMI

1491

L.N.P. Vilela, R. Basílio, J.F. Citadini, J.R. Furaer, F. Rodrigues
LNLS, Campinas, Brazil

The Delta undulator is a compact adjustable-phase insertion device that provides full light polarization control. Five undulators of this type will be installed in the initial operation phase of Sirius, the new 4th generation synchrotron light source that is being built by the Brazilian Synchrotron Light Laboratory (LNLS). In this work we present the recent advances in the development of Sirius Delta-type undulator, the studies of the effects of this device in the storage ring beam dynamics and assembly and measurements strategies.

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TUPMK014

Dipole Fringe Field Analysis of the NSLS-II Storage Ring

dipole, storage-ring, optics, simulation

1519

J. Choi, Y. Hidaka, T.V. Shaftan, C.J. Spataro, G.M. Wang
BNL, Upton, Long Island, New York, USA

Funding: DOE Contract No. DE-SC0012704
In the NSLS-II storage ring, the effect of the dipole fringe field is not negligible and was considered already at the design phase. Especially in the vertical direction, the standard simulation codes are using the parameter called FINT (fringe Field INTegral) and, if there is no specific information, it is usually set to 0.5 which is considered as the reasonable average. With the hall-probe measurement data of the NSLS-II storage ring dipoles, we evaluated measured FINTs and applied them to the beam simulation. The paper shows the resulting FINTs and their effects.

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TUPMK018

Round Beam Studies at NSLS-II

coupling, emittance, resonance, experiment

1529

Y. Hidaka, W.X. Cheng, Y. Li, T.V. Shaftan, G.M. Wang
BNL, Upton, Long Island, New York, USA

Funding: The study is supported by U.S. DOE under Contract No. DE-AC02-98CH10886.
Instead of typical flat beam, some synchrotron light us-ers prefer round beam, i.e., with equal horizontal and vertical emittance, for various reasons (e.g., simplified optics, smaller fraction of photons getting discarded, better phase space match between photon and e-beam). Several future upgrade storage rings such as APS-U, ALS-U, and SLS-2 currently plan to operate in round beam mode. We report our beam study results on round beam operating at NSLS-II by driving linear difference cou-pling resonance.

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TUPML017

Longitudinal Phase Space Reconstruction at FLASHForward Using a Novel Transverse Deflection Cavity, PolariX-TDS

plasma, experiment, dipole, simulation

1567

R.T.P. D'Arcy, A. Aschikhin, P. González Caminal, V. Libov, J. Osterhoff
DESY, Hamburg, Germany

The FLASHForward project at DESY is an innovative beam-driven plasma-wakefield acceleration (PWFA) experiment, aiming to accelerate electron beams to GeV energies over a few centimeters of ionized gas. These accelerated beams are assessed for their capability to drive a free-electron laser. The ultra short, low emittance, and low energy spread properties of bunches produced from certain PWFA injection schemes naturally lend themselves to this task. However, these bunch lengths, typically in the few femtosecond range, are difficult to temporally resolve with traditional diagnostic methods. In order to longitudinally diagnose these bunches it is necessary to utilise the properties of a transverse RF deflecting cavity operating in a high-frequency regime. It is proposed that this type of X-band transverse deflection system, styled the PolariX-TDS due to its novel variable polarisation feature, will be introduced to the FLASHForward beam line in order to perform these single-shot longitudinal phase space measurements. This paper will concern itself with the efficacy of longitudinally reconstructing PWFA-bunches expected at FLASHForward with this TDS, with a focus on the variable bunch properties expected from early commissioning of the experiment.

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TUPML038

Simulation of Phase-Dependent Transverse Focusing in Dielectric Laser Accelerator Based Lattices

focusing, laser, emittance, quadrupole

1622

F. Mayet, R.W. Aßmann, U. Dorda, W. Kuropka
DESY, Hamburg, Germany
W. Kuropka, F. Mayet
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

Funding: Gordon and Betty Moore Foundation. Grant GBMF4744
The Accelerator on a CHip International Program (ACHIP) funded by the Gordon and Betty Moore Foundation aims to demonstrate a prototype of a fully integrated accelerator on a microchip based on laser-driven dielectric structures until 2021. Such an accelerator on a chip needs all components known from classical accelerators. This includes an electron source, accelerating structures and transverse focusing arrangements. Since the period of the accelerating field is connected to the drive laser wavelength of typically a few microns, not only longitudinal but also transverse effects are strongly phase-dependent even for few femtosecond long bunches. If both the accelerating and focusing elements are DLA-based, this needs to be taken into account. In this work we study in detail the implications of a phase-dependent focusing lattice on the evolution of the transverse phase space of a transported bunch.

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TUPML067

Recent Results from the Study of Emittance Evolution in MICE

emittance, solenoid, detector, experiment

1699

V. Blackmore
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

Funding: STFC, DOE, NSF, INFN, and CHIPP
The Muon Ionization Cooling Experiment (MICE) has measured the evolution of emittance due to ionization energy loss. Muons were focused onto an absorber using a large aperture solenoid. Lithium-hydride and liquid hydrogen-absorbers have been studied. Diagnostic devices were placed upstream and downstream of the focus, enabling the phase-space coordinates of individual muons to be reconstructed. By observing the properties of ensembles of muons, the change in beam emittance was measured. Data taken during 2016 and 2017 are currently under study to evaluate the change in emittance due to the absorber for muon beams with various initial emittance, momenta, and settings of the magnetic lattice. The current status and the most recent results of these analyses will be presented.

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WEXGBE2

Compensation of Insertion Device Induced Emittance Variations in Ultralow Emittance Storage Rings

emittance, wiggler, electron, photon

1751

F. Sannibale, S.C. Leemann, H. Nishimura, D. Robin, C. Steier, C. Sun, M. Venturini
LBNL, Berkeley, California, USA

Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231.
With the advent of multi-bend achromat lattices, extremely low emittances are to become the norm in storage ring-based X-ray photon sources. In these lattices, the ratio of beam energy lost to radiation in the Insertion Devices (IDs) to the overall beam energy loss is relatively larger than in 3rd generation light sources. As a result, these machines are more sensitive to the energy loss variations occurring as the users operate variable-gap IDs and to the concurrent variations in radiation damping time, equilibrium emittance, and ultimately transverse properties of the beam. With possibly tens of variable gap IDs continuously and independently varying their gaps to meet the experiment needs, the resulting variation in emittance and beam sizes can be significant and can jeopardize the experimental performance in some of the beamlines. In this paper we describe and discuss possible methods for compensating such emittance variations and maintaining constant transverse beam properties for the experiments.

Slides WEXGBE2 [4.543 MB]

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WEYGBE1

Suppressing CSR Microbunching in Recirculation Arcs

bunching, dipole, emittance, radiation

1784

C.-Y. Tsai
SLAC, Menlo Park, California, USA

We provide sufficient conditions for suppression of CSR-induced microbunching instability along transport or recirculation arcs. The example lattices include low-energy (∼100 MeV) and high-energy (∼1 GeV) recirculation arcs, and medium-energy compressor arcs. Our studies show that lattices satisfying the proposed conditions indeed have microbunching gain suppressed. Beam current dependencies of maximal CSR microbunching gains are also demonstrated, which should help outline a beam line design for different scales of nominal currents. We expect this analysis can improve future lattice design.

Slides WEYGBE1 [10.975 MB]

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WEPAF009

Optimising Response Matrix Measurements for LOCO Analysis

storage-ring, coupling, distributed, quadrupole

1826

Y.E. Tan
AS - ANSTO, Clayton, Australia

The Linear Optics from Closed Orbit (LOCO) method is a common tool for determining storage ring lattice functions and requires a measured BPM to Corrector response matrix. For very large rings with many correctors, such measurements can be time consuming. The following study investigates how the number of correctors and the signal-to-noise ratio (SNR) affects the LOCO analysis results. For the Australian Synchrotron, the results show that four distributed correctors per plane with a SNR of >1000 is sufficient to fit the betatron functions to an accuracy of less than 0.2%.

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WEPAF032

An Alternative Fast Orbit Feedback Design of HEPS

feedback, emittance, controls, closed-orbit

1888

X.Y. Huang, J.S. Cao, Y.Y. Du, F. Liu, Y.H. Lu, Y.F. Ma, Y.F. Sui, S.J. Wei, Q. Ye, X.E. Zhang, D.C. Zhu
IHEP, Beijing, People's Republic of China

The High Energy Photon Source (HEPS) is a fourth generation light source in China and will be built in this year. The emittance of HEPS storage ring is approaching diffraction limit and the circumstance of the ring is about 1.3 kilometres. To stabilize the electron beam, fast orbit feedback (FOFB) system is prerequisite. In this paper, the requirements on the HEPS beam stability are discussed and an alternative FOFB design based on DBPM are introduced with algorithm and architecture.

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WEPAF041

Use of Dimension-Reduction Techniques With Multi-Objective Genetic Algorithms to Improve the Vertical Emittance and Orbit at CESR

emittance, storage-ring, simulation, electron

1901

W.F. Bergan, I.V. Bazarov, C.J. Duncan, D. L. Rubin
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
D. Liarte, J.P. Sethna
Cornell University, Ithaca, New York, USA

Funding: DOE DE-SC0013571 NSF DGE-1650441
In order to reduce the vertical emittance at the Cornell Electron Storage Ring (CESR), we first measure and correct the vertical orbit, dispersion, and coupling. However, due to the finite resolution of our optics measurements, we still retain a significant residual emittance. In order to correct this further, we made use of the theory of sloppy models, according to which certain high-dimensionality systems can be modeled with significantly fewer "eigenparameters" that still contain most of the effect on the desired objective, in this case, the emittance.* However, we noted that using these knobs for tuning often resulted in increased vertical orbit errors. In an attempt to constrain these, we have applied multi-objective genetic algorithms to this problem. We have found that it can be more efficient to run such algorithms using our eigenparameters as the genes to be varied, as opposed to the raw magnet values. When running with the first 8 such knobs as genes, we can get either orbits or beam sizes as good as we obtain with our regular emittance-tuning algorithm which uses all the corrector magnets.
*K.S. Brown and J.P. Sethna, Phys. Rev. E 68, 021904 (2003).

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WEPAF050

Simulations of 3D Charge Density Measurements for Commissioning of the PolariX-TDS

cavity, simulation, electron, MMI

1930

D. Marx, R.W. Aßmann, R.T.P. D'Arcy, B. Marchetti
DESY, Hamburg, Germany

The prototype of a novel X-band transverse deflection structure, the Polarizable X-band (PolariX) TDS*, is currently being prepared for installation in the FLASHForward beamline** at DESY in early 2019. This structure will have the novel feature of variable polarization of the deflecting mode, allowing bunches to be streaked at any transverse angle, rather than at just one angle as in a conventional cavity. By combining screen profiles from several streaking angles using tomographic reconstruction techniques, the full 3D charge density of a bunch can be obtained***. It is planned to perform this measurement for the first time during commissioning of the structure. In this paper, simulations of this measurement are presented and the effects of jitter are discussed.
*P Craievich et al. paper THPAL068, this conference
**A Aschikhin et al. Nucl. Instr. Meth. Phys. Res. A., vol.806, pp.175-183, 2018
***D Marx et al. J. Phys.: Conf. Ser., vol.874, p.012077, 2017

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WEPAF054

Online Multi Objective Optimisation at Diamond Light Source

injection, sextupole, controls, EPICS

1944

M. Apollonio, R. Bartolini, R.T. Fielder, I.P.S. Martin
DLS, Oxfordshire, United Kingdom
R. Bartolini
JAI, Oxford, United Kingdom
G. Henderson
Oxford University, Physics Department, Oxford, Oxon, United Kingdom
J. Rogers
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

At Diamond Light Source we have developed an Optimization Package currently used online to improve the performance of the machine, usually measured in terms of lifetime, injection efficiency or beam disturbance at injection. The tool is flexible in that control variables in order to optimise objectives (or their functions) can be easily specified by means of EPICS process variables (PV), making it suitable for virtually any sort of optimization. At present three different algorithms can be used to perform optimizations in a multi-objective fashion: Multi-Objective Genetic Algorithm (MOGA), Particle Swarm Optimizer (MOPSO) and Simulated Annealing (MOSA). We present a series of tests aimed at characterizing the algorithm as well as improving the performance of the machine itself.

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WEPAL062

Bunch Length Measurements with a Streak Camera in Low Alpha Lattice Operation at the TPS

synchrotron, operation, photon, emittance

2316

C.H. Chen, J.Y. Chen, M.-S. Chiu, P.J. Chou, K.T. Hsu, K.H. Hu, C.-C. Kuo, C.C. Liang, C.Y. Liao, Y.-C. Liu, G.-H. Luo, H.-J. Tsai, F.H. Tseng
NSRRC, Hsinchu, Taiwan

We developed and tested lattice with lower momentum compaction factor (low alpha) in TPS (Taiwan Photon Source) recently. Operating low alpha lattice can provide picosecond bunch length for time-resolved research and coherent IR/THz synchrotron light. The bunch length around 2.5 picosecond rms was measured by a streak camera* in low alpha mode while operating in the routine users mode** it was around 10 picosecond. This paper presents the related processes and measurements.
* L.Y. Liao et al., "Preliminary beam test of synchrotron radiation monitoring system at Taiwan Photon Source", IPAC'15.
** C.C. Kuo et al., "Commissioning of Taiwan Photon Source", IPAC'15.

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WEPMF011

Design and Status of Sirius Light Source RF Systems

cavity, storage-ring, booster, LLRF

2391

R.H.A. Farias, A.P.B. Lima, L. Liu, F.S. Oliveira
LNLS, Campinas, Brazil

Sirius is the new synchrotron light source currently under construction at the site of the Brazilian Synchro-tron Light Laboratory (LNLS) in Campinas, Brazil. The facility comprises a 3 GeV electron storage ring, a full energy booster and a 150 MeV linac. This work provides a brief description of the RF system of the booster and storage ring, presenting their main characteristics and specification goals.

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WEPMF021

Magnet Design Considerations for an Ultralow Emittance Canadian Light Source

quadrupole, emittance, storage-ring, FEL

2413

L.O. Dallin, D. Bertwistle
CLS, Saskatoon, Saskatchewan, Canada

The strong focusing requirements for ultralow emittance light sources result in high field magnets that are very close together. High fields are readily achieved by using small magnet gaps. This is possible due to the small beam sizes involved. Reduction in the physical aperture and the reduction in the good field region requirements results in magnets with compact transverse dimensions. The very strong focusing of the magnets results in very small drift spaces between the various magnetic elements. To keep these drift spaces clear magnets with recessed coils have been studied. In such magnets the coils do not stick out beyond the end of the magnet yoke in the longitudinal direction. By placing the coils on the outer yoke loss of efficiency can be avoided while maintaining good control of the higher order field harmonics. This is very well suited for quadrupole magnets where only two coils are required. Possible designs for gradient dipoles and sexutpoles are also considered.

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WEPMF035

Investigating the Effect of Inhomogeneous Resistivity on Bulk RRR and Heat Conductivity Using a Lattice Green's Functions Method

cavity, network, niobium, HOM

2436

N.C. Shipman, A. Macpherson
CERN, Geneva, Switzerland
G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
J.A. Mitchell
Lancaster University, Lancaster, United Kingdom

A method was developed to calculate the bulk RRR (residual resistivity ratio) which would be measured on a superconducting cavity or sample with an inhomogeneous resistivity and arbitrary geometry. The method involves modelling the object as a network of resistors and employs lattice Green's functions. A further adaptation of the method which allows the heat transport characteristics of such an object to be predicted is also described.

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THXGBD1

The Upgrade of the Advanced Photon Source

feedback, controls, cavity, simulation

2872

M. Borland, M. Abliz, N.D. Arnold, T.G. Berenc, J.M. Byrd, J.R. Calvey, J.A. Carter, J. Carwardine, H. Cease, Z.A. Conway, G. Decker, J.C. Dooling, L. Emery, J.D. Fuerst, K.C. Harkay, A.K. Jain, M.S. Jaski, P.S. Kallakuri, M.P. Kelly, S.H. Kim, R.M. Lill, R.R. Lindberg, J. Liu, Z. Liu, J. Nudell, C.A. Preissner, V. Sajaev, N. Sereno, X. Sun, Y.P. Sun, S. Veseli, J. Wang, U. Wienands, A. Xiao, C. Yao
ANL, Argonne, Illinois, USA
A. Blednykh
BNL, Upton, Long Island, New York, USA

After decades of successful operation as a 7-GeV synchrotron radiation source, the Advanced Photon Source is pursing a major upgrade that involves replacement of the storage ring with an ultra-low emittance multi-bend achromat design. Using a seven-bend hybrid multi-bend achromat with reverse bending magnets gives a natural emittance of 42 pm operated at 6 GeV. The x-ray brightness is predicted to increase by more than two orders of magnitude. Challenges are many, but appear manageable based on thorough simulation and in light of the experience gained from world-wide operation of 3^\text{rd}-generation light sources. The upgraded ring will operate in swap-out mode, which has allowed pushing the performance beyond the limits imposed by conventional operation.

Slides THXGBD1 [14.684 MB]

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THPAF014

Studies of the Single-Bunch Instabilities in the Booster of HEPS

booster, impedance, storage-ring, injection

2971

H.S. Xu, Z. Duan, J.L. Li, Y.M. Peng, S.K. Tian, N. Wang
IHEP, Beijing, People's Republic of China

High Energy Photon Source (HEPS), which is proposed in China, is an ultra-low emittance storage ring based synchrotron light source. Because of the requirement of the relatively high single-bunch charge, the booster may suffer from the single-bunch instabilities. A preliminary impedance model has been developed for the studies of collective instabilities in the booster. Based on this impedance model, the longitudinal and transverse single-bunch instabilities have been studied.

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THPAF021

Start to End Simulation of the CBETA Energy Recovery Linac

linac, simulation, optics, space-charge

2993

W. Lou, A.C. Bartnik, J.A. Crittenden, C.M. Gulliford, G.H. Hoffstaetter, D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
J.S. Berg, S.J. Brooks, F. Méot, D. Trbojevic, N. Tsoupas
BNL, Upton, Long Island, New York, USA
C.E. Mayes
SLAC, Menlo Park, California, USA

Funding: This manuscript has been authored by employees of Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
CBETA is an energy recovery linac accelerating from 6 MeV to 150 MeV in four linac passes, using a single return line accepting all energies from 42 MeV to 150 MeV. We simulate a 6-dimensional particle distribution from the injector through the end of the dump line. Space charge forces are taken into account at the low energy stages. We compare results using field maps to those using simpler magnet models. We introduce random and systematic magnet errors to the lattice, apply an orbit correction algorithm, and study the impact on the beam distribution.

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THPAF022

Beam Breakup Studies for the 4-Pass Cornell-Brookhaven Energy Recovery Linac Test Accelertor

HOM, simulation, cavity, dipole

2996

W. Lou, G.H. Hoffstaetter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Cornell University and Brookhaven National Laboratory are currently designing the Cornell-BNL ERL-FFAG Test Accelerator (CBETA). To be built at Cornell Wilson Lab, CBETA utilizes the existing ERL injector and main linac cryomodule (MLC). As the electron bunches pass through the MLC cavities, higher order modes (HOMs) fields are excited. The recirculating bunches interact with the HOMs, which can give rise to beam-breakup instability (BBU). We would present simulation results on how BBU limits the maximum achievable current, and potential ways to improve the threshold current.

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THPAF028

Multi-Objectives Genetic Algorithms (MOGA) Optimization of PETRA IV Scenarios

injection, sextupole, SRF, dynamic-aperture

3015

X.N. Gavaldà, J. Keil, R. Wanzenberg
DESY, Hamburg, Germany

This paper reports the application of Multi-Objective Genetic Algorithms (MOGA) to optimize the linear and nonlinear beam dynamics of the different PETRA IV scenarios to transform PETRA III storage ring in a diffracted limited one. As it is well known, the dynamic aperture and momentum acceptance of these kinds of lattices are dramatically reduced due to the increase of the sextupoles strengths to compensate its strong focusing. The reduction of the dynamic aperture jeopardizes the current off-axis injection system and lower beam lifetimes increase the beam instabilities and the radiation safety concerns of the storage ring. MOGA searches the best settings of quadrupoles and sextupoles in a multi-dimensional parameter space taking into account the dynamic properties and the natural emittance as objectives at the level of ten picometers. The lattices studied are the so-called 'Twist lattice' based in a phase space exchange lattice, a solution based in the ESRF-Hybrid Multi-bend Achromat (HMA) design and finally the 'double 'I' lattice combining a non-interleaved sextupoles cell with an ESRF-HMA cell.

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THPAF031

A PETRA IV Lattice based on Hybrid Seven Bend Achromats

emittance, damping, wiggler, sextupole

3021

J. Keil, I.V. Agapov, R. Brinkmann, X.N. Gavaldà, R. Wanzenberg
DESY, Hamburg, Germany

For the PETRA IV project at DESY it is planned to convert the 6 GeV synchrotron light source PETRA III into a diffraction limited storage ring with ultra-low emittances. PETRA IV should provide a natural emittance two orders of magnitude smaller as now. The energy and the current of 100 mA should be unchanged. Currently different lattice options are investigated to achieve an emittance in the range of 10-30 pm*rad. As one candidate for a lattice of PETRA IV a ring based on the concept of hybrid multi-bend achromats (HMBA) has been studied in detail. Due to the unique layout of PETRA III with long straight sections it is possible to use damping wigglers to reduce the emittance further. While this helps to mitigate intrabeam scattering it has the disadvantage of an increased energy spread. The linear and nonlinear parameters of this HMBA-based lattice and the influence of damping wigglers on beam parameters are discussed.

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THPAF045

Performance Optimisation of Turn-by-Turn Beam Position Monitor Data Harmonic Analysis

betatron, optics, software, electron

3064

L. Malina, J.M. Coello de Portugal, J. Dilly, P.K. Skowroński, R. Tomás, M.S. Toplis
CERN, Geneva, Switzerland
J.M. Coello de Portugal
UPC, Barcelona, Spain

Nowadays, turn-by-turn beam position monitor data is increasingly utilized in many accelerators, as it allows for fast and simultaneous measurement of various optics parameters. The accurate harmonic analysis of turn-by-turn data costs beam time when needed online. Generally, the electronic noise is avoided by cleaning of the data based on singular value decomposition. In this paper, we exploit the cleaning procedure to compress the data for the harmonic analysis. This way the harmonic analysis is sped up by an order of magnitude. The impact on measurement accuracy is discussed.

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THPAF055

Space Charge Studies on LEIR

resonance, space-charge, emittance, simulation

3095

Á. Saá Hernández, H. Bartosik, N. Biancacci, S. Hirlaender, A. Huschauer, D. Moreno Garcia
CERN, Geneva, Switzerland

The performance of the CERN Low Energy Ion Ring with electron cooled ion beams is presently limited by losses occurring once the beam has been captured in the RF buckets. An intense machine study program was started by the end of 2015 to mitigate the losses and improve the performance of the accelerator. The measurements pointed to the interplay of direct space charge forces and excited betatron resonances as the most plausible driving mechanism of these losses. In this paper, we present the systematic space-charge measurements performed in 2017 and compare them to space-charge tracking simulations based on an adaptive frozen potential.

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THPAF059

Ultra Compact Symplectic Scheme for Fast Multi-Particle Tracking

flattop, target, octupole, sextupole

3107

K. Skoufaris, Y. Papaphilippou, D. Pellegrini
CERN, Geneva, Switzerland

A versatile symplectic integration scheme has been developed in order to produce simplified versions of non linear lattices, preserving fundamental non-linear properties such as the detuning with amplitude and energy, in addition to the linear transport. The method has been applied to the LHC and benchmarked against tracking simulations with Sixtrack. This reduced lattice is made available as a refined replacement of the simple rotation matrix often used in multi-particle studies requiring a fast beam transport routine.

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THPAF060

A Benchmark Study of a High Order Symplectic Integration Method With Only Positive Steps

quadrupole, sextupole, multipole, target

3111

K. Skoufaris, Y. Papaphilippou
CERN, Geneva, Switzerland
J. Laskar
IMCCE, Paris, France
Ch. Skokos
University of Cape Town, Cape Town, South Africa

The symplectic integrators CSABA & CSBAB are used in order to calculate single particles dynamics in accelerators and storage rings. These integrators include only forward drift steps while being highly accurate. Their efficiency to describe various optical and dynamical quantities for main magnetic elements and non-linear lattices is calculated and compared with the efficiency of the splitting methods used in MAD-X - PTC.

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THPAF067

Effects of Synchrotron Motion on Nonlinear Integrable Optics

synchrotron, optics, coupling, betatron

3131

S.D. Webb, N.M. Cook
RadiaSoft LLC, Boulder, Colorado, USA
J.S. Eldred
Fermilab, Batavia, Illinois, USA

Funding: This work was supported in part by the Department of Energy, Office of Science, Office of High Energy Physics under contract number DE-SC0011340.
An integrable Rapid-Cycling Synchrotron (iRCS) has been proposed as a replacement for the Fermilab Booster to achieve multi-MW beam power for the Fermilab high-energy neutrino program.* The successful application of nonlinear integrable optics to proton synchrotrons requires careful examination of single-particle longitudinal effects, especially synchrotron motion. For example, synchrobetatron coupling may excite transverse resonances in the ring. We will use the Synergia code to simulate the effects of this synchrobetatron coupling on the iRCS design with nonlinear inserts. Our goal will be to identify new invariants in the presence of this coupling. Assuming the synchrotron tune is sufficiently small, we have identified one or more adiabatic invariants of the motion. These invariants suggest that integrable optics with synchrobetatron coupling retains integrability when averaged over a synchrotron period.
* J. Eldred and A. Valishev, "Design Considerations for Proposed Fermilab Integrable RCS," arXiv 1703.00952 (2017).

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THPAF068

Suppression of Instabilities Generated by an Anti-Damper With a Nonlinear Magnetic Element in IOTA

simulation, experiment, optics, damping

3134

E.G. Stern, J.F. Amundson, A. Macridin
Fermilab, Batavia, Illinois, USA

Funding: US Department of Energy
The Integrable Optics Test Accelerator (IOTA) storage ring is being constructed at Fermilab as a testbed for new accelerator concepts. One important series of experiments tests the use of a novel nonlinear magnetic insert to damp coherent instabilities. To test the damping power of the ele- ment, an instability of desired strength may be intentionally excited with an anti-damper. We report on simulations of beam stabilization using the Synergia modeling framework over ranges of driving and damping strengths.

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THPAF070

Design of a One-Dimensional Sextupole Using Semi-Analytic Methods

sextupole, quadrupole, coupling, focusing

3140

L. Gupta
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
S. Baturin
Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA
Y.K. Kim
University of Chicago, Chicago, Illinois, USA
S. Nagaitsev
Fermilab, Batavia, Illinois, USA

Funding: Work supported by the U.S. National Science Foundation under Award No. PHY-1549132, the Center for Bright Beams
Sextupole magnets provide position-dependent momentum kicks and are tuned to provide the correct kicks to particles within a small acceptance region in phase space. Sextupoles are useful and even necessary in circular accelerators for chromaticity corrections. They are routinely used in most rings, i.e. CESR. Although sextupole magnets are necessary for particle energy corrections, they also have undesirable effects on dynamic aperture, especially because of their non-linear coupling term in the momentum kick. Studies of integrable systems suggest that there is an analytic way to create transport lattices with specific transfer matrices that limit the momentum kick to one dimension. A one-dimension sextupole is needed for chromaticity corrections: a horizontal sextupole for horizontal bending magnets. We know how to make a "composite" horizontal sextupole using regular 2D sextupoles and linear transfer matrices in an ideal thin-lens approximation. Thus, one could create an accelerator lattice using linear elements, in series with sextupole magnets to create a '1d sextupole'. This paper describes progress towards realizing a realistic focusing lattice resulting in a 1d sextupole.*
*S.A. Antipov, et. al., Single-particle dynamics in a nonlinear accelerator lattice: attaining a large tune spread with octupoles in IOTA, Journal of Instrumentation, Volume 12, April 2017.

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THPAF071

McMillan Lens in a System with Space Charge

emittance, simulation, resonance, quadrupole

3143

I. Lobach
University of Chicago, Chicago, Illinois, USA
S. Nagaitsev, E.G. Stern, T. Zolkin
Fermilab, Batavia, Illinois, USA

Space charge (SC) in a circulating beam in a ring produces both betatron tune shift and betatron tune spread. These effects make some particles move on to a machine resonance and become unstable. Linear elements of beam optics cannot reduce the tune spread induced by SC because of its intrinsic nonlinear nature. We investigate the possibility to mitigate it by a thin McMillan lens providing a nonlinear axially symmetric kick, which is qualitatively opposite to the accumulated kick by SC. Experimentally, the proposed concept can be tested in Fermilab's IOTA ring. A thin McMillan lens can be implemented by a short (70 cm) insertion of an electron beam with specifically chosen density distribution in transverse directions. In this article, to see if McMillan lenses reduce the tune spread induced by SC, we make several simulations with particle tracking code Synergia. We choose such beam and lattice parameters that tune spread is roughly 0.5 and a beam instability due to the half-integer resonance 0.5 is observed. Then, we try to reduce emittance growth by shifting betatron tunes by adjusting quadrupoles and reducing the tune spread by McMillan lenses.

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THPAF073

Beam Phase Space Tomography at Fast Electron Linac at Fermilab

experiment, coupling, MMI, linac

3146

A.L. Romanov
Fermilab, Batavia, Illinois, USA

FAST linear accelerator has been commissioned in 2017. Experimental program of the facility requires high quality beams with well-defined properties. Solenoidal fields at photoinjector, laser spot shape, space charge forces and other effects can distort beam distribution and introduce coupling. This work presents results of a beam phase space tomography for a coupled 4D case. Beam was rotated in two planes with seven quads by 180 degrees and images from YaG screen were used to perform SVD based reconstruction of the beam distribution.

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THPAF075

Numerical Simulations of Space Charge Compensation with an Electron Lens

space-charge, electron, simulation, emittance

3154

E.G. Stern, Y.I. Alexahin, J.F. Amundson, A.V. Burov, A. Macridin, V.D. Shiltsev
Fermilab, Batavia, Illinois, USA

The future high energy physics program at Fermilab requires that the proton complex operate with beam bunch intensities four times larger than is currently handled. At these intensities space charge nonlinear defocussing effects cause unacceptable particle losses especially in the low energy rapid-cycling-synchrotron (RCS) Booster. Focusing electron lens elements may offer a solution by providing partial space charge compensation but there is a need for detailed simulations as this technique has not been demonstrated. We report on high fidelity numerical 6D space charge simulations in a model accelerator lattice with a record high space charge tune shift approaching unity.

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THPAF084

Impact of RF Coupler Kicks on Beam Dynamics in BESSY VSR

cavity, simulation, kicker, SRF

3182

T. Mertens
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany
T. Atkinson, F. Glöckner, A. Jankowiak, M. Ries, A.V. Tsakanian
HZB, Berlin, Germany

The expected BESSY II upgrade to BESSY VSR requires the installation of a superconducting RF system, consisting of four cavities. Two cavities will operate at 1.5 GHz and two at 1.75 GHz. Each of them is equipped with a Fundamental Power Coupler and with Higher Order Mode (HOM) damping waveguide couplers. Dedicated simulations of these cavities and couplers have shown that at the location of the FPC the beam will see a transverse kick [*], perturbing the closed orbit and affecting transverse beam dynamics. We present the results of simulations and experiments of the impact on transverse beam dynamics of these coupler induced kicks for different FPC orientations.
[*] Study on RF Coupler Kicks of SRF Cavities in the BESSY VSR Module
A. Tsakanian#, H.-W. Glock, T. Mertens, M. Ries, A. Velez, J. Knobloch
IPAC18

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THPAK008

Space Charge and Microbunching Studies for the Injection Arc of MESA

space-charge, bunching, simulation, injection

3221

A. Khan, O. Boine-Frankenheim
Institut Theorie Elektromagnetischer Felder, TU Darmstadt, Darmstadt, Germany
C.P. Stoll
IKP, Mainz, Germany

For intense electron bunches traversing through bends, as for example the recirculation arcs of an ERL, space charge (SC) may result in beam phase space deterioration. SC modifies the electron transverse dynamics in dispersive regions along the beam line and causes emittance growth for mismatched beams or for specific phase advances. On the other hand, longitudinal space charge together with dispersion can lead to the microbunching instability. The present study focuses on the 180° low energy (5 MeV) injection arc lattice for the multi-turn Mainz Energy-recovering Superconducting Accelerator (MESA), which should deliver a CW beam at 10⁵ MeV for physics experiments with an internal target. We will discuss matching conditions with space charge together with the estimated microbunching gain for the arc. The implication for the ERL operation will be outlined, using 3D envelope and tracking simulations.
Supported by the DFG through GRK 2128

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THPAK024

A new method to measure the Beta function in a Paul trap

dipole, experiment, emittance, resonance

3262

L. Martin, S.L. Sheehy
JAI, Oxford, United Kingdom
K. Ito, H. Okamoto
HU/AdSM, Higashi-Hiroshima, Japan
D.J. Kelliher
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
S. Machida
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

The Simulator of Particle Orbit Dynamics (S-POD) is a linear Paul trap at Hiroshima University, Japan, used to study beam physics. S-POD has so far been used to study resonances in high intensity beams, predominantly using a simple alternating gradient lattice configuration. Recently a similar apparatus, the Intense Beam Experiment (IBEX), has been constructed at the Rutherford Appleton Lab in the UK. To use either of these experiments to study beam dynamics in more complex lattice configurations in the future further diagnostic techniques must be developed for Paul traps. Here we describe a new method to measure the beta function and emittance at a given time in a Paul trap.

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THPAK035

Numerical Tools for Modeling Nonlinear Integrable Optics in IOTA with Intense Space Charge Using the Code IMPACT-Z

space-charge, optics, simulation, proton

3290

C.E. Mitchell, J. Qiang
LBNL, Berkeley, California, USA

Funding: This work is supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
The Integrable Optics Test Accelerator (IOTA) is a novel storage ring under commissioning at Fermi National Accelerator Laboratory designed to investigate the dynamics of beams with large transverse tune spread in the presence of strongly nonlinear integrable optics. Several new numerical tools have been implemented in the code IMPACT-Z to allow for high-fidelity modeling of the IOTA ring during Phase II operation with intense proton beams. A primary goal is to ensure symplectic treatment of both single-particle and collective dynamics. We describe these tools and demonstrate their application to modeling nonlinear integrable dynamics with space charge in IOTA.

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THPAK036

Accurate Modeling of Fringe Field Effects on Nonlinear Integrable Optics in IOTA

optics, quadrupole, octupole, betatron

3294

C.E. Mitchell, R.D. Ryne
LBNL, Berkeley, California, USA
F.H. O'Shea
RadiaBeam, Santa Monica, California, USA

Funding: This work is supported by the U.S. Department of Energy, Office of High Energy Physics.
The Integrable Optics Test Accelerator (IOTA) is a novel storage ring under commissioning at Fermi National Accelerator Laboratory designed to investigate the dynamics of beams with large transverse tune spread in the presence of strongly nonlinear integrable optics. Uncontrolled nonlinear effects resulting from magnetic fringe fields can affect the integrability of particle motion, and long-term numerical tracking requires an accurate representation of these effects. Surface fitting algorithms provide a robust and reliable method for extracting this information from 3-dimensional magnetic field data provided on a grid. These algorithms are applied to investigate the unique nonlinear magnetic insert of the IOTA ring, and consequences of the fringe fields to the long-term dynamics of the beam are discussed.

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THPAK040

Bunched Beam Envelope Instability in a Periodic Focusing Channel

emittance, focusing, simulation, solenoid

3301

J. Qiang
LBNL, Berkeley, California, USA

The space-charge driven envelope instability presents a great danger in high intensity accelerator design. In this paper, we report on the study of bunched beam envelope instability in a periodic focusing channel using three-dimensional envelope model for a 3D uniform Waterbag distribution and a 3D Gaussian distribution. Our results show that the envelope instability stopband becomes broader with the increase of longitudinal focusing and are not sensitive to the type of distribution. Self-consistent macroparticle simulations using both distributions show similar structure in emittance growth but also extra instability stopbands. The emittance growth from the Waterbag distribution has larger stopband than that from the Gaussian distribution.

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THPAK042

On Long-Term Space-Charge Tracking Simulation

space-charge, simulation, emittance, optics

3305

J. Qiang
LBNL, Berkeley, California, USA

The nonlinear space-charge effects in high intensity accelerator can degrade beam quality and cause particle losses. Self-consistent macroparticle tracking simulations have been widely used to study these space-charge effects. However, it is computationally challenging for long-term tracking simulation of these effects. In this paper, we study a fully symplectic self-consistent particle-in-cell model and numerical methods to mitigate numerical emittance growth. We also discuss about a fast alternative frozen space-charge model that has a potential to improve computational speed significantly.

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THPAK049

Simulation Code Design for the Interpreted Language Using the Compiled Module

simulation, interface, EPICS, linac

3327

K. Fukushima, M.A. Davidsaver, Z.Q. He, M. Ikegami, G. Shen, T. Yoshimoto, T. Zhang
FRIB, East Lansing, USA
J. Qiang
LBNL, Berkeley, California, USA

Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DESC0000661.
We are planning to use two types of the accelerator simulation codes for FRIB (Facility for Rare Isotope Beams). One is the linear envelope tracking code "FLAME" for fast simulations. FLAME can calculate the FRIB-linac beam envelope within an order of ms. This is useful in systematic surveys, wide range optimizations and so forth. This code, written in C++, was designed with Python interface from the beginning. On the other hand, "Advanced-IMPACT" is the particle tracking code dedicated for precise and realistic calculations, which can simulate the particle losses, nonlinear and space-charge effects. This code is refactored from the Fortran code IMPACT-Z developed in LBNL. Both codes provide the compiled modules for Python to support flexible inputs and direct outputs management in memory. In other words, they can be directly connected to the modern scientific tools through the Python interface without delay in the data transport. In addition, these modules can accomplish the interactive simulation processes without losing computational efficiency. We report the knowledges applicable for other accelerator simulation codes among those obtained through these developments and designs.

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THPAK054

Optics Calibration and Measurement for Low Alpha Lattices in TPS Storage Ring

emittance, optics, coupling, operation

3343

F.H. Tseng, C.H. Chen, J.Y. Chen, P.C. Chiu, C.H. Huang, C.-C. Kuo, C.C. Liang, C.Y. Liao, Y.-C. Liu, H.-J. Tsai
NSRRC, Hsinchu, Taiwan

In order to provide short-pulse radiation for pump-probe experiments and coherent radiation for THz/IR measurements, we develop low alpha lattices to reduce the momentum compaction factor from nominal operation values 2.4*10^-4 to 2.6*10-5 or lower. The corresponding bunch length at 2.8 MV RF voltage and zero current are from 10.78 ps to 3.55 ps or less. In the low alpha operations, the bunch lengthening as a function of bunch current, the orbit drift and noise enhancements as well as rf stability effect are observed. In this report we will present our studies on the lattice design, optics correction, beam parameters measurements and alpha measurements.

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THPAK063

Electron Beam Pattern Rotation as a Method of Tunable Bunch Train Generation

electron, laser, HOM, experiment

3372

A. Halavanau, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
P. Piot
Fermilab, Batavia, Illinois, USA

Transversely modulated electron beams can be formed in photo injectors via microlens array (MLA) UV laser shaping technique. Micro lenses can be arranged in polygonal lattices, with resulting transverse electron beam modulation mimicking the lenses pattern. Conventionally, square MLAs are used for UV laser beam shaping, and generated electron beam patterns form square beamlet arrays. The MLA setup can be placed on a rotational mount, thereby rotating electron beam distribution. In combination with transverse-to-longitudinal emittance exchange beam line, it allows to vary beamlets horizontal projection and tune electron bunch train. In this paper, we extend the technique to the case of different MLA lattice arrangements and explore the benefits of its rotational symmetries.

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THPAK064

Theoretical Modeling of Electromagnetic Field from Electron Bunches in Periodic Wire Medium

radiation, simulation, electron, FEL

3376

S.S. Chuchurka, A.I. Benediktovitch
BSU, Minsk, Belarus, Belarus
S.N. Galyamin, V.V. Vorobev
Saint Petersburg State University, Saint Petersburg, Russia
A. Halavanau
Northern Illinois University, DeKalb, Illinois, USA

Funding: Work supported by the Grant from Russian Foundation for Basic Research (No. 17-52-04107).
The interaction of relativistic electrons with periodic structures results in radiation by a number of mechanisms. In case of crystals one obtains parametric X-ray radiation, its frequency is determined by distance between crystallographic planes and direction of electron beam. If instead of crystal one considers a periodic structure of metallic wires with period of the order of mm, one can expect emission of THz radiation. In the present contribution we consider theoretical approaches for modeling of the distribution of electromagnetic field from electron bunches in lattice formed by metallic wires. The analytical description is possible for the case of wires with small radius, the range of validity is checked by numerical simulations. The intensity of radiation will be significantly increased if the electrons in the bunch could radiate coherently. Two possibilities will be discussed: the prebunching of the beam and the self-modulation of the beam due to interaction with radiated field.

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THPAK082

Simulation of Perturbative Effects in IOTA

simulation, optics, octupole, emittance

3422

C.C. Hall, D.L. Bruhwiler, N.M. Cook, J.P. Edelen, S.D. Webb
RadiaSoft LLC, Boulder, Colorado, USA

The Integrable Optics Test Accelerator (IOTA) is being commissioned at Fermi National Laboratory for study of the concept of nonlinear integrable optics. The use of a special nonlinear magnetic element introduces large tune spread with amplitude while constraining the idealized dynamics by two integrals of motion. The nonlinear element should provide suppression of instabilities through nonlinear decoherence. We examine the case of a bunch injected off-axis and the resulting damping of centroid oscillations from decoherence. A simple model of the damping is described and compared to simulation.

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THPAK085

3D Space Charge in Bmad

space-charge, simulation, software, brightness

3428

C.E. Mayes
SLAC, Menlo Park, California, USA
R.D. Ryne
LBNL, Berkeley, California, USA
D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

We present a parallel fast Fourier transform based 3D space charge software library based on integrated Green functions. The library is open-source, and has been structured to easily be used by existing beam dynamics codes. We demonstrate this by incorporating it with the Bmad toolkit for charged particle simulation, and compare with analytical formulas and well-established space charge codes.

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THPAK108

Fourier Coefficients of Long-Range Beam-Beam Hamiltonian via Two-Dimensional Bessel functions

resonance, optics, emittance, TRIUMF

3486

D. Kaltchev
TRIUMF, Vancouver, Canada

The two-dimensional coefficients (resonance basis) in the Fourier expansion of the long-range beam-beam Hamiltonian have been expressed through the (less familiar) generalized modified Bessel functions of two arguments. We describe an efficient method to compute these coefficients based on the above representation. The method has been applied to HL-LHC lattices and benchmarked against MadX simulations of detuning.

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THPAK126

Revised Optics Design for the JLEIC Ion Booster

booster, sextupole, injection, betatron

3537

E.W. Nissen, T. Satogata
JLab, Newport News, Virginia, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
We outline the recently redesigned booster for the pro-posed Jefferson Lab Electron Ion Collider (JLEIC). This booster will inject protons (or ions of equivalent rigidity) at 280 MeV and accelerate them to 8 GeV kinetic energy. To avoid transition crossing, the booster uses flexible momentum compaction (FMC) lattices to raise the transi-tion gamma above the reach of the machine. We also include several families of sextupoles to simultaneously control the chromaticities, and nonlinear dispersions that were excited by the FMC cells.

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THPAK129

Modeling Challenges for Energy Recovery Linacs With Long, High Charge Bunches

bunching, space-charge, electron, recirculation

3544

C. Tennant
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Historically, nearly all energy recovery linacs (ERLs) built and operated were used to drive a free-electron laser (FEL). The requirement for high peak current bunches necessitates bunch compression and handling the attendant beam dynamical challenges. In recent years, ERLs have turned from being drivers of light sources toward applications for nuclear physics experiments, Compton backscattering sources and strong electron cooling. Unlike an FEL, these latter uses require long, high charge bunches with small energy spread. The electron bunch must maintain a small projected energy spread and therefore must avoid gross distortion due to CSR and longitudinal space charge over a single (or multiple) recirculations. Accurately modeling the relevant collective effects in the system 'space charge, microbunching instability, CSR and the effect of shielding' in addition to beam dynamical processes such as halo, presents a formidable challenge. Absent a code that models all of these effects, we outline an approach towards the design, analysis and optimization of the high-energy electron cooler for the Jefferson Lab Electron-Ion Collider and survey widely used codes and their capabilities.

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THPAK137

Beam-Based Sextupolar Nonlinearity Mapping in CESR

sextupole, simulation, experiment, resonance

3565

L. Gupta, Y.K. Kim
University of Chicago, Chicago, Illinois, USA
S. Baturin
Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA
M.P. Ehrlichman, J.M. Maxson, R.E. Meller, D. L. Rubin, D. Sagan, J.P. Shanks
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Work supported by the U.S. National Science Foundation under Award No. PHY-1549132, the Center for Bright Beams
In order to maintain beam quality during transport through a storage ring, sextupole magnets are used to make chromatic corrections, but necessarily introduce deleterious effects such as nonlinear resonances and reduced dynamic aperture. Implementing intricate sextupole distributions to mitigate these effects will rely on precision beam-based measurement of the applied sextupole distribution. In this work, we generalize previous sextupole mapping techniques by using resonant phase-locked excitation of the beam at the Cornell Electron Storage Ring (CESR), which accounts for variations in the normal mode tunes on a turn by turn basis. The methods presented here are applied to simulation and actual turn by turn data in CESR for both simplified and realistic sextupole distributions.

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THPAK143

Tuning Low-Current Beam for Nonlinear Quasi-Integrable Optics Experiments at the University of Maryland Electron Ring

octupole, optics, experiment, quadrupole

3585

K.J. Ruisard, H. Baumgartner, B.L. Beaudoin, S. Bernal, B. M. Cannon, L. Dovlatyan, I. Haber, T.W. Koeth
UMD, College Park, Maryland, USA

Funding: Travel was supported by the NSF, the APS DPB, and TRIUMF. Funding for the work was provided through DOE-HEP Award DESC0010301, NSF Award PHY1414681 and the NSF GRFP program.
Design of accelerator lattices with nonlinear integrable optics is a novel approach to suppress transverse resonances and may be crucial for enabling low-loss high-intensity beam transport. Lattices with large amplitude-dependent tune spreads, driven by strong nonlinear magnet inserts, have reduced response to resonant driving perturbations [*]. This paper describes preparations for tests of a quasi-integrable octupole lattice at the University of Maryland Electron Ring (UMER). The planned tests employ a low-current highemittance beam with low space charge tune shift (∼ 0.005) to probe the dynamics of a lattice with large external tune spread (∼ 0.26).
* V. Danilov and S. Nagaitsev, Nonlinear accelerator lattices
with one and two analytic invariants, PRSTAB, 13, 084002, 2010.

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THPAK145

Methods to Increase the Dynamic Aperture of the FCC-hh Lattice

dynamic-aperture, luminosity, quadrupole, interaction-region

3593

E. Cruz Alaniz, J.L. Abelleira, A. Seryi, L. van Riesen-Haupt
JAI, Oxford, United Kingdom
J.L. Abelleira, L. van Riesen-Haupt
University of Oxford, Oxford, United Kingdom
R. Martin, R. Tomás
CERN, Geneva, Switzerland

The Future Circular Collider (FCC) design study aims to develop the designs of possible circular colliders in the post LHC era. In particular the FCC-hh will aim to produce proton-proton collisions at a center of mass energy of 100 TeV. Initial tracking studies for the FCC-hh lattice at collision energy including field errors on the final focus triplet showed a very low dynamic aperture, most likely affected by the large beta functions and integrated length of the quadrupoles. Using non-linear correctors, the dynamic aperture was increased to acceptable levels; however, the difficulty to have an accurate magnetic model of the magnets required for this correction motivates the development of alternative methods. This work explores the possibility to increase the dynamic aperture by optimizing the phase advance between the main interaction regions. The description of this method along with its impact on the dynamic aperture will be given on this paper.

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THPAK147

Super-Period Multi-Bend Achromat Lattice with Interleaved Dispersion Bumps for the HALS Storage Ring

storage-ring, sextupole, emittance, controls

3597

Z.H. Bai, L. Wang
USTC/NSRL, Hefei, Anhui, People's Republic of China

We have proposed a multi-bend achromat (MBA) lattice concept, called the MBA with interleaved dispersion bumps, in which two pairs of interleaved dispersion bumps are created in each lattice cell. Due to that many nonlinear effects can be effectively cancelled out within one cell and also many knobs can be used for nonlinear optimization, this MBA concept has given both large dynamic aperture (DA) and large dynamic momentum aperture in the lattice design of the Hefei Advanced Light Source (HALS). In this paper, to further enlarge DA, we extend the concept to the case of a super-period lattice consisting of two cells. In the super-period lattice, there are 1.5 pairs of bumps in each cell. A super-period 7BA lattice is preliminarily designed for the HALS, and a larger DA is obtained.

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THPAK148

Preliminary Study of a Nine-Bend Achromat Lattice for a Diffraction-Limited Storage Ring

emittance, storage-ring, sextupole, synchrotron

3600

P.H. Yang, Z.H. Bai, L. Wang
USTC/NSRL, Hefei, Anhui, People's Republic of China

In recent years, multi-bend achromat (MBA) lattices have been widely used for the design of diffraction-limited storage rings (DLSRs) being developed around the world as the next-generation storage ring synchrotron sources. To better solve the problem of very serious non-linear dynamics in the DLSR lattice design, recently we proposed a new MBA lattice concept called the MBA lattice with interleaved dispersion bumps *, which was then applied to designing 7BA lattices for the Hefei Ad-vanced Light Source (HALS), with the result showing rather good nonlinear dynamics performance. In this paper, a 9BA lattice also following our MBA concept is preliminarily designed as a possible option for the HALS with a natural emittance of less than 30 pm·rad. Since generally the 9BA lattice can have a much lower emit-tance than the usually used 7BA lattice, the work in the paper will provide an inspiration for the existing third-generation synchrotron sources to upgrade to DLSRs with much lower emittances.
* Zhenghe Bai et al., MOPH13, Proc. SAP2017, Jishou, China, 2017.

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THPAK153

Linac Optics Correction With Trajectory Scan Data

quadrupole, linac, optics, storage-ring

3606

X. Huang, Y.-C. Chao, T.J. Maxwell
SLAC, Menlo Park, California, USA
T. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

We proposed and tested a scheme to measure and correct linac optics by scanning the beam trajectory in the horizontal and vertical phase spaces. The trajectory data are compared to tracking data in a fitting scheme, from which we can derive the quadrupole strength errors. Simulation is carried out to evaluate the requirements and the performance of the method. The method is experimentally applied to FEL linacs.

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THPAL020

Design of Asymmetric Quadrupole Gradient Bending R&D Magnet for the Advanced Light Source Upgrade (ALS-U)

dipole, quadrupole, multipole, simulation

3667

J.-Y. Jung, M. Leitner, N. Li, E.R. San Mateo, C. Steier, C.A. Swenson, M. Venturini
LBNL, Berkeley, California, USA

Lawrence Bekerley National Laboratory (LBNL) is en-gaged in the development of magnets for the upgrade of the ALS synchrotron (ALS-U) [1]. The proposed ALS-U lattice is a 9-bend achromat reproducing the existing 12-fold symmetric ALS foot print. The ALS-U lattice requires strong focusing elements and the dipole magnet requires high gradient larger than 46 T/m. This paper presents the detailed design of the R&D dipoles under construction.

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THPAL037

Nano-engineering of Nb3Sn Thin Films to Improve Wire Performance and Reduce Cost

collider, electron, coupling, dipole

3720

S.A. Kahn, M.A. Cummings
Muons, Inc, Illinois, USA
E.Z. Barzi
Fermilab, Batavia, Illinois, USA

State-of-the-art Nb3Sn wires have plateaued in the performance of the critical current density Jc. Chemical and geometrical optimization of the wire layout have produced Nb3Sn wires with average Jc(4.2K, 16T) ~ 1,300 A/mm2. A future high energy hadron collider that is being considered to follow the LHC would need larger Jc and be cost effective. The approach to improving the performance of Nb3Sn conductor would be to introduce enhanced flux pinning mechanisms with nano-engineering techniques.

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THPAL142

Surface Characterization of NbTiN Films for Accelerator Applications

site, SRF, FEL, detector

3975

D.R. Beverstock, M.J. Kelley, C.E. Reece, J.K. Spradlin, A-M. Valente-Feliciano
JLab, Newport News, Virginia, USA

Funding: Work supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The development of next-generation SRF cavities requires the deployment of innovative material solutions with RF performance beyond bulk Nb. Theoretical interest has stimulated efforts to grow and characterize thin multi-layer superconductor/insulator/superconductor (SIS) structures for their potential capability of supporting otherwise inaccessible surface magnetic fields in SRF cavities *. The ternary B1-compound NbTiN is among the candidate superconducting materials for SIS structures. Single crystal NbTiN films with thicknesses below 15 nm are also of interest for the development of high resolution, high sensitivity (SNSPD) detectors for particle physics application. Using DC reactive magnetron sputtering, NbTiN can be deposited with nominal superconducting parameters. This contribution presents the on-going material surface and superconducting properties characterization in order to optimize the NbTiN films for each application.
* A Gurevich, "Maximum screening fields of superconducting multilayer structures", AIP ADVANCES 5, 017112 (2015)

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THPMF002

Studies for Injection with a Pulsed Multipole Kicker at ALBA

injection, kicker, storage-ring, octupole

4030

G. Benedetti, U. Iriso, M. Pont, D. Ramos Santesmases
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
E. Ahmadi
ILSF, Tehran, Iran

Injection into the ALBA storage ring presently uses a conventional local injection bump with four dipole kickers. However, following the promising results of the first tests with single multipole kicker injection at other light sources, studies to implement this new injection scheme have been started for ALBA. Two possible designs for the kicker have been considered: a pure octupole and a non-linear magnet similar to the BESSY type. A comparison between the expected performances of the two kicker designs has been carried out in terms of injection efficiency and transparency for the users. This paper summarises the beam dynamics results from multi-particle tracking simulations and the proposed kicker magnet design.

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THPMF005

Evaluating the Impact of Diamond-II Possible Lattices on Beamlines

photon, radiation, synchrotron, emittance

4033

M. Apollonio, L. Alianelli, F. Bakkali Taheri, R. Bartolini, A.J. Dent
DLS, Oxfordshire, United Kingdom
R. Bartolini, J. Li
JAI, Oxford, United Kingdom

At Diamond Light Source we are considering an upgrade of the machine aimed at significantly reduced emittance (la factor 20), that follows a worldwide trend in similar synchrotron radiation sources. An important aspect in the design of the upgrade is the optimization of the photon beam properties, such as flux, brilliance, spot size, divergence or coherence of the new sources and how these are translated into requirements on the electron beam and on the machine design. We present a study based on a combination of accelerator physics tracking codes (AT, elegant) and of radiation codes (SPECTRA, SRW, SHADOW), with the aim at bridging the gap between machine and beamlines.

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THPMF006

Control of the Nonlinear Dynamics for Medium Energy Synchrotron Light Sources

controls, storage-ring, optics, synchrotron

4037

J. Bengtsson, R. Bartolini, H. Ghasem, B. Singh
DLS, Oxfordshire, United Kingdom
A. Streun
PSI, Villigen PSI, Switzerland

MAX-IV has introduced a paradigm shift in the design philosophy for the "Engineering-Science" in the quest for a diffraction limited Synchrotron Light Source. Similarly, SLS-2 has introduced a systematic method for controlling the Linear Optics beyond some 20 years of TME inspired paper designs; by introducing Reverse Bends to disentangle dispersion and focusing, which enables Longitudinal Gradient Bends to efficiently reduce the emittance. Similarly, we outline a systematic approach for how to control the Nonlinear Dynamics for these systems, by a method that was pioneered for the conceptual design of the Swiss Light Source in the mid-1990s; subsequently benchmarked and validated by the commissioning.

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THPMF008

Conceptual Design of an Accumulator Ring for the Diamond II Upgrade

emittance, injection, storage-ring, dynamic-aperture

4046

I.P.S. Martin, R. Bartolini
DLS, Oxfordshire, United Kingdom
R. Bartolini
JAI, Oxford, United Kingdom

Diamond Light Source is in the process of reviewing several lattice options for a potential storage ring upgrade. As part of these studies, it has become clear that a substantial reduction in emittance can be achieved by adopting an on-axis injection scheme, thereby relaxing the constraints on the dynamic aperture. In order to achieve the necessary injected bunch properties for this to be viable, a new accumulator ring would be needed. In this paper we review the requirements placed on the accumulator ring design, describe the lattice development process and analyse the performance of the initial, conceptual design.

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THPMF009

Lattice Options for DIAMOND-II

emittance, injection, sextupole, linear-dynamics

4050

B. Singh, R. Bartolini, J. Bengtsson, H. Ghasem
DLS, Oxfordshire, United Kingdom
R. Bartolini
JAI, Oxford, United Kingdom
A. Streun
PSI, Villigen PSI, Switzerland

Funding: Diamond Light Source Ltd
Generalized MBA (Multi-Bend-Achromat) Chasman-Green type lattices, with a low-dispersion mid-straight, have been studied and refined by pursuing a generalized Higher Order Achromat to control the non-linear dynamics to obtain a robust design. New candidate lattice have been produced aiming for a horizontal emittance of 150 pm×rad for off-axis injection and 75 pm×rad for on-axis, the latter making use of reverse bends. The results of these studies and evaluations have been summarized in this paper.

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THPMF010

Status of Elettra and Future Upgrades

operation, dipole, emittance, status

4054

E. Karantzoulis, A. Carniel, R. De Monte, S. Krecic, C. P. Pasotti
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

The operational status of the Italian 2.4/2.0 GeV third generation light source Elettra is presented together with the possible future upgrades especially concerning the next ultra low emittance light source Elettra 2.0

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THPMF019

ESRF-EBS Lattice Model with Canted Beamlines

SRF, optics, MMI, quadrupole

4081

S.M. Liuzzo, N. Carmignani, J. Chavanne, L. Farvacque, T.P. Perron, P. Raimondi, S.M. White
ESRF, Grenoble, France

The ESRF Extremely Brilliant Source (ESRF-EBS) lattice model is updated to include three canted beamlines. The cells are modified where necessary to include 3-Pole Wiggler (3PW), 2-Pole Wiggler (2PW) and Short Bending Magnet (SBM) sources. Several lattices are obtained for the different stages that will bring from commissioning to operation with users. A scheme for tune modification keeping key optics knobs unchanged is proposed.

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THPMF020

A 4th Generation Light Source for South-East Europe

emittance, SRF, storage-ring, synchrotron

4084

H. Ghasem, R. Bartolini
DLS, Oxfordshire, United Kingdom
D. Einfeld
ESRF, Grenoble, France

In Europe, most of the Synchrotron Light Sources are located in the middle, west and northern regions while the south-east is still lacking any major project. Hence a new initiative has been set up to propose the construction of a 4th Generation Light Source in that region. Design requirements limit the beam energy between 2.5 GeV to 3 GeV, the circumference is limited to 350 m, the emittance should be smaller than 250 pm rad and at least 14 to 16 straights have to be available for the users. Several mag-net configurations have been investigated and the results revealed that the HMBA lattice can fully meets the requirements and is therefore proposed for the Light Source in the SEE-region of Europe. These studies show that for a 4th Generation Light Source with energies up to 3 GeV a circumferences of 350 m will be adequate.

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THPMF036

Status of the Conceptual Design of ALS-U

emittance, vacuum, kicker, cavity

4134

C. Steier, A.P. Allézy, A. Anders, K.M. Baptiste, E.S. Buice, K. Chow, G.D. Cutler, S. De Santis, R.J. Donahue, D. Filippetto, J.P. Harkins, T. Hellert, M.J. Johnson, J.-Y. Jung, S.C. Leemann, D. Leitner, M. Leitner, T.H. Luo, H. Nishimura, T. Oliver, O. Omolayo, J.R. Osborn, G.C. Pappas, S. Persichelli, M. Placidi, G.J. Portmann, S. Reyes, D. Robin, F. Sannibale, C. Sun, C.A. Swenson, M. Venturini, S.P. Virostek, W.L. Waldron, E.J. Wallén
LBNL, Berkeley, California, USA

Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The ALS-U conceptual design promises to deliver diffraction limited performance in the soft x-ray range by lowering the horizontal emittance to about 70 pm rad resulting in two orders of brightness increase for soft x-rays compared to the current ALS. The design utilizes a nine bend achromat lattice, with reverse bending magnets and on-axis swap-out injection utilizing an accumulator ring. This paper shows some aspects of the completed conceptual design of the accelerator, as well as some results of the R&D program that has been ongoing for the last years.

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THPMF053

Study of the Dynamic Aperture Reduction Due to Error Effects for the High Energy Photon Source

sextupole, quadrupole, optics, closed-orbit

4182

Z. Duan, D. Ji, Y. Jiao
IHEP, Beijing, People's Republic of China

Funding: Work supported by Natural Science Foundation of China(No.11605212).
The 6 GeV High Energy Photon Source (HEPS) employs a lattice of 48 hybrid 7BA cells, aims to achieve a natural emittance between 30 to 60 pm, within a circumference of about 1.3 km. In the performance evaluation of optimized lattices, we found that the dynamic aperture of the bare lat- tice were su cient for on-axis swap-out injection, but a large reduction in the dynamic aperture was observed in the simu- lation when including lattice imperfections and even after dedicated lattice corrections. In this paper, we identi ed the feed-down e ects of sextupoles as the major source of DA reduction, and proposed to use dedicated sextupole movers to e ciently reduce the orbit o sets in sextupoles, to par- tially recover the dynamic aperture, sextupole mover-based optics correction schemes were also discussed.

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THPMF055

Ion Instability Simulation in the HEPS Storage Ring

electron, simulation, storage-ring, emittance

4189

S.K. Tian, Y. Jiao, N. Wang
IHEP, Beijing, People's Republic of China
K. Ohmi
KEK, Ibaraki, Japan

The High Energy Photon Source (HEPS), a kilometre scale storage ring light source, with a beam energy of 6 GeV and transverse emittances of a few tens of pm.rad, is to be built in Beijing and now is under design. We investigate the ion instability in the storage ring with high beam intensity and low-emittance. We performe a weak-strong simulation to show characteristic phenomena of the instability in the storage ring.

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THPMF059

Simulation Studies of Beam Commissioning and Expected Performance of the SPring-8-II Storage Ring

emittance, quadrupole, simulation, sextupole

4203

Y. Shimosaki
JASRI, Hyogo, Japan
K. Soutome, M. Takao
JASRI/SPring-8, Hyogo-ken, Japan
H. Tanaka
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

In the SPring-8 upgrade project, the 5-bend achromat lattice is adopted for achieving a very low emittance of 157 pm.rad at 6 GeV. Since the dynamic aperture (DA) and the beam performance become sensitive against errors due to the strong quadrupoles and sextupoles, we carried out tracking simulations to evaluate the tolerance of machine imperfections such as the misalignment, magnetic field errors, the BPM offset, etc. It is found that the first-turn-steering (FTS) with the use of single-pass BPM's is indispensable because even under strict (but attainable) tolerances the beam cannot be stored without steering kicks. We then confirmed that after the FTS a sufficiently large DA can be obtained for accumulating the beam by the off-axis injection. By performing the orbit and optics corrections for the stored beam, we can finally achieve an emittance value of 160 ~ 180 pm.rad, being close to the design value. We also found that a naive application of the SVD algorithm to orbit corrections yields unwanted local bumps between BPM's and this deteriorates the vertical emittance. A possible scheme to avoid such local bumps by effectively interpolating the measured orbit will be discussed.

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THPMF071

Design of a Very Large Acceptance Compact Storage Ring

laser, storage-ring, electron, sextupole

4239

A.I. Papash, E. Bründermann, A.-S. Müller, R. Ruprecht, M. Schuh
KIT, Eggenstein-Leopoldshafen, Germany

Design of a very large acceptance compact storage ring is underway at the Institute for Beam Physics and Technology of the Karlsruhe Institute of Technology (Germany). Combination of a compact storage ring and a laser wake-field accelerator (LWFA) might be the basis for future compact light sources and advancing user facilities. Meanwhile the post-LWFA beam is not fitted for storage and accumulation in conventional storage rings. New generation rings with adapted features are required. Different geometries and lattices of a ring operating between 50 to 500 MeV energy range were investigated. The model suitable to store the post-LWFA beam with a wide momentum spread (1% to 2%) and ultra-short electron bunches of fs range was chosen as basis for further detailed studies. The DBA-FDF lattice with relaxed settings, split elements and high order optics of tolerable strength allows improving the dynamic aperture up to 20 mm. The momentum acceptance of the compact lattice exceeds 8% while dispersion is limited. The physical program includes turn-by-turn phase compression of a beam, crab cavities, dedicated alpha optics mode of operation, non-linear insertion devices etc.

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THPMF077

A Novel 7BA Lattice for a 196-m Circumference Diffraction-Limited Soft X-Ray Storage Ring

emittance, focusing, optics, sextupole

4252

S.C. Leemann, W.E. Byrne, M. Venturini
LBNL, Berkeley, California, USA
J. Bengtsson
DLS, Oxfordshire, United Kingdom
A. Streun
PSI, Villigen PSI, Switzerland

Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract No. DEAC02-05CH11231
The current baseline for the ALS Upgrade to a diffraction-limited soft x-ray storage ring is a 9BA lattice with two dispersion bumps for localized chromatic corrections. Although this lattice meets the very aggressive emittance goal, it offers limited margins in terms of dynamic aperture and momentum acceptance. In this paper we explore a different approach based on a 7BA lattice with distributed chromatic correction. This lattice relies heavily on longitudinal gradient bends and reverse bending in order to suppress the emittance so that despite fewer bends an emittance comparable to the baseline lattice can be reached albeit with larger dynamic aperture and momentum acceptance. We present linear optics design, trade-offs between achievable emittance and longitudinal stability, as well as the employed nonlinear tuning approach and the resulting performance of this alternate lattice.

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THPMF078

Simulation of Trajectory Correction in Early Commissioning of the Advanced Light Source Upgrade

MMI, simulation, sextupole, closed-orbit

4256

T. Hellert, J.-Y. Jung, S.C. Leemann, H. Nishimura, D. Robin, F. Sannibale, C. Steier, C. Sun, C.A. Swenson, M. Venturini
LBNL, Berkeley, California, USA

Funding: *Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231.
The ALS upgrade into a diffraction-limited soft x-rays light source requires a small emittance, which is achieved by much stronger focusing than in the present ALS. Very strong focusing elements and a relatively small vacuum chamber make the required rapid commissioning a significant challenge. This paper will describe the progress towards a start-to-end simulation of the machine commissioning and present first simulation results.

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THPMK015

Low Momentum Compaction Lattice Operation of the Taiwan Photon Source

emittance, storage-ring, operation, quadrupole

4325

C.-C. Kuo, C.H. Chen, J.Y. Chen, P.C. Chiu, K.T. Hsu, K.H. Hu, C.H. Huang, C.C. Liang, C.Y. Liao, Y.-C. Liu, Z.K. Liu, H.-J. Tsai, F.H. Tseng
NSRRC, Hsinchu, Taiwan

In order to provide short bunch length for picosecond time-resolved experiments and for coherent IR/THz radiation, low momentum compaction factor (alpha) lattices have been commissioned recently at the Taiwan Photon Source (TPS). The momentum compaction can be positive or negative and its value can be reduced by more than two orders of magnitude. In this paper, we discuss variable low alpha lattice optics, its beam dynamics issues, the measured momentum compaction and bunch lengths as well as beam orbit stability issues, etc.

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THPMK029

Towards an Upgrade of the Swiss Light Source

storage-ring, emittance, sextupole, injection

4358

A. Streun, M. Aiba, M. Böge, T. Garvey, V. Schlott
PSI, Villigen PSI, Switzerland

An upgrade of the Swiss Light Source (SLS) is planned for the period 2021-24. The existing 12-TBA (triple bend achromat) lattice will be exchanged by a 12-7BA (7-bend achromat) lattice in order to reduce the emittance from present 5.5 nm down to about 125 pm at 2.4 GeV / 400 mA (IBS included). The new lattice is based on longitudinal gradient bends and reverse bends to realize low emittance despite the small circumference of 290 m. A conceptual design has been established. We present project status, lattice design and work in progress with emphasis on beam dynamics issues.

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THPMK071

Lattice Design for a 1.2 GeV Storage Ring

emittance, dipole, storage-ring, optics

4464

S.Q. Shen, S.Q. Tian, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

It is a very effective way to bring down the emittance of storage ring by using the MBA lattice design. Based on this concept, some other solutions have been developed to reduce the emittance furthermore for recent years. In this paper, the lattice design for a 1.2 GeV storage ring will be presented. The solution of horizontal and longitudinal gradient bending magnets tried in this lattice is going to be discussed in detailed.

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THPMK105

PERLE - Lattice Design and Beam Dynamics Studies

linac, bunching, injection, electron

4556

S.A. Bogacz, D. Douglas, F.E. Hannon, A. Hutton, F. Marhauser, R.A. Rimmer, Y. Roblin, C. Tennant
JLab, Newport News, Virginia, USA
D. Angal-Kalinin, J.W. McKenzie, B.L. Militsyn, P.H. Williams
Cockcroft Institute, Warrington, Cheshire, United Kingdom
G. Arduini, O.S. Brüning, R. Calaga, K.M. Dr. Schirm, F. Gerigk, B.J. Holzer, E. Jensen, A. Milanese, E. Montesinos, D. Pellegrini, P.A. Thonet, A. Valloni
CERN, Geneva, Switzerland
S. Bousson, D. Longuevergne, G. Olivier, G. Olry
IPN, Orsay, France
I. Chaikovska, W. Kaabi, A. Stocchi, C. Vallerand
LAL, Orsay, France
B. Hounsell, M. Klein, U.K. Klein, P. Kostka, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
E.B. Levichev, Yu.A. Pupkov
BINP SB RAS, Novosibirsk, Russia

Funding: Work has been authored by Jefferson Science Associates, LLC under Contract No. DE-AC05-06OR23177 with the U.S. Department of Energy.
PERLE (Powerful ERL for Experiments) is a novel ERL test facility, initially proposed to validate choices for a 60 GeV ERL foreseen in the design of the LHeC and the FCC-eh. Its main thrust is to probe high current, CW, multi-pass operation with superconducting cavities at 802 MHz (and perhaps testing other frequencies of interest). With very high virtual beam power (~ 10 MW), PERLE offers an opportunity for controllable study of every beam dynamic effect of interest in the next generation of ERL design; becoming a ‘stepping stone' between present state-of-art 1 MW ERLs and future 100 MW scale applications. PERLE design features Flexible Momentum Compaction lattice architecture for six vertically stacked return arcs and a high-current, 6 MeV, photo-injector. With only one pair of 4 cavity cryomodules, 400 MeV beam energy can be reached in 3 re-circulation passes, with beam currents in excess of 15 mA. The beam is decelerated in 3 consecutive passes back to the injection energy, transferring virtually stored energy back to the RF. This unique facility will serve as a test-bed for high current ERL technologies, as well as a user facility in low energy electron and photon physics.

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THPMK120

Hefei Advanced Light Source: A Future Soft X-Ray Diffraction-Limited Storage Ring at NSRL

storage-ring, emittance, radiation, injection

4598

L. Wang, Z.H. Bai, N. Hu, H.T. Li, W. Li, G. Liu, Y. Lu, Q. Luo, D.R. Xu, W. Xu, P.H. Yang, Z.H. Yang, S.C. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

To meet the fast-growing demands for high-quality low-energy photon beams, a new synchrotron radiation light source conception was brought forward several years ago by National Synchrotron Radiation Laboratory, which was named Hefei Advanced Light Source (HALS). The dominant radiation of HALS will be located in the VUV and soft X-ray region, which will be complementary with that of SSRF and HEPS. Except for high brilliance, high transverse coherence will be another signature feature of HALS. To achieve these goals, a multi-bend achromat based diffraction-limited storage ring was adopted as the main body of HALS. The general description and preliminary design of HALS will be briefly presented in this paper. Under the support of the Chinese Academy of Sciences and local government, the preliminary research and development (R&D) for HALS is undergoing. Several key technologies will be developed in the R&D project, which will lay good foundation for the construction of HALS.

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THPMK121

Design of the Second Version of the HALS Storage Ring Lattice

emittance, storage-ring, dipole, linear-dynamics

4601

Z.H. Bai, W. Li, L. Wang, P.H. Yang, Z.H. Yang
USTC/NSRL, Hefei, Anhui, People's Republic of China

In this paper, a new multi-bend achromat (MBA) lat-tice concept that we recently proposed for diffraction-limited storage rings is described, where two pairs of interleaved dispersion bumps are created in each cell and also most of the nonlinear effects produced by the sextupoles located in these bumps can be cancelled out within one cell. Following this concept, two 7BA lattices have been designed for the Hefei Advanced Light Source storage ring as the second version lattic-es, one with uniform dipoles and the other with nonu-niform dipoles. The latter has a lower natural emit-tance of 23 pm·rad, in which longitudinal gradient bends and anti-bends are employed. The optimized nonlinear dynamics for these two lattices are rather good, and especially the dynamic momentum aperture can be larger than 8% without off-momentum tunes crossing non-structure half-integer resonance lines.

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THPMK129

Lattice Tweaking Using A Tune Knob Based On Global Mechanism

storage-ring, quadrupole, injection, simulation

4620

S.W. Wang, B. Li, J.L. Li, W.B. Wu, W. Xu, X. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China
J.L. Li
IHEP, Beijing, People's Republic of China

The transverse tunes are important parameters for a storage ring and tune knobs are used to adjust the tunes in a specific range. Usually for large rings, a set of quadrupoles is set on the straight sections for the use of tune knob. A tune knob has been designed for the HLS-II storage ring without affecting the twiss parameters of the injection section. This paper introduces the design and online test of this tune knob. The quadrupoles are adjusted according to the simulation results and the tunes are measured and calibrated. The online test results show that the tune knob design works well on the HLS-II storage ring and can be applied for various machine studies.

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THPMK135

Corrector Layout Optimization Using NSGA-II for HALS

closed-orbit, dipole, storage-ring, sextupole

4629

D.R. Xu, Z.H. Bai, L. Wang, W. Wang, H. Xu
USTC/NSRL, Hefei, Anhui, People's Republic of China

In this paper, we present a method to find the global optimum correctors layout based NSGA-II algorithm when the number of correctors is limited to be equal to the number of BPMs. We prove that this method works well with HALS.

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THPMK144

Lattices for a 4th-Generation Synchrotron Light Source

synchrotron, emittance, SRF, radiation

4639

G. K. Shamuilov
Uppsala University, Uppsala, Sweden

Inspired by the ESRF upgrade (Extremely Brilliant Source, EBS), I present some modern lattices for a medium-sized 4th-generation synchrotron radiation source. They incorporate new elements, such as anti-bend magnets. The composed lattices are optimized using a simple double-objective algorithm. Its goal is to minimize the natural emittance and absolute chromaticities simultaneously. Then, the lattices are analyzed and compared to a version of the ESRF-EBS lattice scaled down in size. The design is performed to meet the needs of the user community of the Siberian Synchrotron and Terahertz Radiation Centre under the umbrella of the Budker Institute of Nuclear Physics.

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THPML011

Possibilities for Fabricating Polymer Dielectric Laser Accelerator Structures with Additive Manufacturing

laser, site, acceleration, electron

4671

E.I. Simakov, R.D. Gilbertson, M.J. Herman, G. Pilania, D.Y. Shchegolkov, E.M. Walker, E. Weis
LANL, Los Alamos, New Mexico, USA
R.J. England, K.P. Wootton
SLAC, Menlo Park, California, USA

Funding: Los Alamos National Laboratory LDRD Program
We present results of recent studies of new materials designed for the additive manufacturing of accelerating structures for dielectric laser accelerators (DLAs). Demonstration of a stand-alone practical DLA requires innovation in design and fabrication of efficient laser accelerator structures and couplers. Many complicated three-dimensional structures for laser acceleration (such as a long woodpile structure with couplers) are difficult to manufacture with conventional microfabrication technologies. LANL has a large effort focused on developing new materials and techniques for additive manufacturing. The materials for DLA structures must have high dielectric constant (larger than 4), low loss in the infrared regime, high laser damage threshold, and be able to withstand the electron beam damage. This presentation will discuss the development of novel infrared dielectric materials that are of interest for laser acceleration and are compatible with additive manufacturing, as well as recent advances in additive manufacturing of dielectric woodpile structures using a Nanoscribe direct laser-writing 3D printer.

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THPML034

Baseline Lattice for the Upgrade of SOLEIL

emittance, photon, injection, storage-ring

4726

A. Loulergue, P. Alexandre, P. Brunelle, O. Marcouillé, A. Nadji, L.S. Nadolski, R. Nagaoka, K.T. Tavakoli, M.-A. Tordeux, A. Vivoli
SOLEIL, Gif-sur-Yvette, France
L. Hoummi
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Previous MBA studies converged to a lattice composed of 7BA-6BA with a natural emittance value of 200- 250 pm.rad range. Due to the difficulties of non-linear optimization in targeting lower emittance values, a decision was made to symmetrize totally the ring with 20 identical cells having long free straight sections longer than 4 m. A 7BA solution elaborated by adopting the sextupole paring scheme with dispersion bumps originally developed at the ESRF-EBS, including reverse-bends, enabling an emittance of 72 pm.rad has been defined as the baseline lattice. The sufficient on-momentum dynamic aperture obtained allows to consider off-axis injection. The linear and nonlinear dynamic properties of the lattice along with the expected performance in terms of brilliance and transverse coherence are presented. In particular, the beta functions tuned down to 1 m in both transverse planes at the center of straight sections allow matching diffraction limited photons up to 3 keV.

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THPML060

Virtual VELA-CLARA: The Development of a Virtual Accelerator

simulation, controls, EPICS, software

4773

T.J. Price, H.M. Castaneda Cortes, D.J. Dunning, J.K. Jones, B.D. Muratori, D.J. Scott, B.J.A. Shepherd, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R.F. Clarke, G. Cox
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

A Virtual Accelerator (VA) has been developed to mimic the accelerators Versatile Electron Linear Accelerator (VELA) and Compact Linear Accelerator for Research and Applications (CLARA). Its purpose is to test control room applications, run start-to-end simulations with multiple simulation codes, accurately reproduce measured beam properties, conduct 'virtual experiments'and gain insight into ‘hidden beam parameters'. This paper gives an overview into the current progress in constructing this VA, detailing the areas of: developing a 'Virtual EPICS' control system, using multiple simulation codes (both particle tracking and analytic), the development of a ‘Master Lattice' and the construction of a Python interface in which to run the VA.

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THPML084

Validating the COBEA Algorithm at the DELTA Storage Ring

storage-ring, optics, betatron, closed-orbit

4851

B. Riemann, B.D. Isbarn, S. Khan, S. Koetter, T. Weis
DELTA, Dortmund, Germany

Closed-Orbit Bilinear-Exponential Analysis (COBEA) is an algorithm to decompose monitor-corrector response matrices into (scaled) beta optics values, phase advances, scaled dispersion and betatron tunes. No explicit magnetic lattice model is required for COBEA - only the sequence of monitors and correctors along the beam path (no lengths, no strengths approach). To obtain absolute beta values, the length of one drift space can be provided as optional input. In this work, the application of COBEA to the DELTA storage ring, operated by TU Dortmund University, is discussed, and its results for betatron tunes and scaled dispersion are compared with those of conventional, direct measurement methods. COBEA is also put in a historical perspective to other diagnostic algorithms. Improvements in the Python implementation of COBEA, which is available as free software, are presented. Due to COBEA being relatively modest regarding its requirements on input data respectively hardware, it should be applicable to the majority of existing storage rings.

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THPML087

First ERL Operation of S-DALINAC and Commissioning of a Path Length Adjustment System

linac, operation, recirculation, MMI

4859

M. Arnold, C. Burandt, R. Grewe, J. Pforr, N. Pietralla, M. Steinhorst
TU Darmstadt, Darmstadt, Germany
C. Eschelbach, M. Lösler
Frankfurt University of Applied Sciences, Frankfurt am Main, Germany
F. Hug
KPH, Mainz, Germany

Funding: Work supported by DFG through GRK 2128 and INST163/383-1/FUGG
The S-DALINAC is running in recirculating operation since 1991. In 2015/2016 a major upgrade was performed by adding a third recirculation beam line. The versatility of this recirculation beam line enables a phase shift of the beam of up to 360° of the RF phase. The required range of 10 cm for a 3 GHz RF frequency is realized by a path length adjustment system. A complementary operation in normal scheme (single-pass, once or thrice recirculating with acceleration) or ERL mode (once or twice) is possible by appropriate adjustment of this system. After installation this system was aligned properly and its functionality and stroke was checked without beam. The system was commissioned by measuring the change of the beam phase in dependency of the setting of the path length adjustment system. The complementary usage of the newly installed recirculation for once recirculating with acceleration and once recirculating with ERL mode has been shown successfully in autumn 2017. This contribution will provide an overview on the path length adjustment system and the first run of the once recirculating ERL mode of the S-DALINAC.

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THPML107

Steering Optimizations for the University of Maryland Electron Ring

closed-orbit, dipole, injection, experiment

4913

L. Dovlatyan, B.L. Beaudoin, R.A. Kishek, K.J. Ruisard
UMD, College Park, Maryland, USA

Funding: This work is supported by the US Dept. of Energy, Office of High Energy Physics award # DE-SC0010301
The University of Maryland Electron Ring (UMER) has the flexibility to set up alternative lattices for different research experiments, including nonlinear optics studies using octupoles. Each alternative lattice requires an acceptable steering solution for use in experiments. Existing beam-based alignment tools can take a significant amount of time to run and become difficult to process with a low number of BPMs. The Robust Conjugate Directional Search (RCDS) optimizer* is used to quickly obtain steering solutions for different lattice configurations and has been adopted for beam steering at UMER. Steering magnets are optimized online to reduce scraping, correct equilibrium orbits, and increase beam lifetimes. This study presents the application of the optimizer at UMER.
* X. Huang, J. Corbett, J. Safranek, J. Wu, Nucl. Instr. Meth. A vol. 726, pp. 77-83, 2013.

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THPML134

Design of the Magnets of the HALS Project

quadrupole, sextupole, dipole, emittance

4998

Z.L. Ren, C. Chen, T.L. He, L. Wang, X.Q. Wang, H. Xu, B. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Work supported by the National Nature Science Foundation of China under Grant Nos.11375176 * hlxu@ustc.edu.cn ** zhbo@ustc.edu.cn
The Hefei Advanced Light Source (HALS) is a future soft X-ray diffraction-limited storage ring at NSRL, this project aims to improve the brilliance and coherence of the X-ray beams and to decrease the horizontal emittance. The lattice of the HALS ring relies on magnets with demanding specifications, including combined function dipole-quadrupoles (DQs) with high gradients, dipoles with longitudinal gradients (DLs), high gradient quadrupoles and strong sextupoles. The combined dipole-quadrupole design developed is between the offset quadrupole and septum quadrupole types. The longitudinal-gradient dipoles are permanent magnets. The quadrupoles and sextupoles rely on a more conventional design. All the magnets have been designed using POSSION, Radia, and OPERA-3D.

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THPML135

Design of the Combined Function Dipole-Quadrupoles (DQS) with High Gradients

quadrupole, dipole, vacuum, storage-ring

5001

Z.L. Ren, C. Chen, T.L. He, L. Wang, X.Q. Wang, H. Xu, B. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Work supported by the National Nature Science Foundation of China under Grant Nos.11375176 * hlxu@ustc.edu.cn **zhbo@ustc.edu.cn
Combined dipole-quadrupoles (DQs) can be obtained with the design of tapered dipole or offset quadrupole. However, the tapered dipole design can not achieve a high gradient field, as it will lead to poor field quality in the low field area of the magnet bore, and the design of offset quadrupole will increase the magnet size and power consumption. Finally, the dipole-quadrupole design developed is between the offset quadrupole and septum quadrupole types. The dimensions of the poles and the coils of the low field side have been reduced. The 2D pole profile is simulated and optimized by using POSSION and Radia, while the 3D modle using Radia and OPERA-3D. The end shimming and chamfer are modelled to meet the field uniformity requirement.

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THPML138

Efficiency and Error Analysis of the HALS Injection Scheme

injection, simulation, kicker, storage-ring

5008

Z.B. Sun, G. Liu, W. Liu, F.L. Shang, L. Shang, W.B. Song
USTC/NSRL, Hefei, Anhui, People's Republic of China

Hefei Advanced Light Source (HALS) is a newly designed diffraction-limited storage ring.. The latest version of HALS has a 7BA lattice. One of the most important parts about HALS design is its injection system. Since conventional injection scheme is not suitable for DLSRs, many new injection schemes are proposed, including longitudinal injection scheme. In this paper, we investigate the feasibility of longitudinal injection scheme for HALS. In order to evaluate the injection performance, various errors have been considered. A series of tracking simulations are carried out and injection efficiency is obtained under different error levels.

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