Paper | Title | Page |
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MOPGW010 | First Application of Online Particle Swarm Optimization at SOLEIL | 82 |
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First attempts of online optimisation of SOLEIL using Particle Swarm Optimisation (PSO) is reported with two major applications. This technique proves to be particularly suitable in a control room and could become a standard operation tool for tuning the accelerators in complement of other techniques. The first optimisation of the injection in the storage ring will be presented using the injection septa and the vertical correctors of the booster to storage ring transfer line. The second work will summarise the results obtained from the optimisation of the transverse on- and off-momentum dynamics in presence of insertion devices. Main results, the implementation and improvements will be presented and discussed thoroughly. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW010 | |
About • | paper received ※ 19 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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MOPGW012 | Study of Fringe Fields Effects from Final Focus Quadrupoles on Beam Based Measured Quantities | 90 |
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Accelerator physics needs advanced modeling and simulation techniques, in particular for beam stability studies. A deeper understanding of the effects of magnetic fields non-linearities will greatly help in the improvement of future colliders design and performance. In *, a new tracking method was proposed to study the effect of the longitudinal dependency of the harmonics on the beam dynamics. In this paper, the study will focus on the effects on observable quantities in beam based measurements, for the case of HL-LHC Inner Triplet and with possible tests in LHC.
* T. Pugnat et al., "Accurate and Efficient Tracking in Electromagnetic Quadrupoles", in Proc. IPAC’18, Vancouver, Canada, June 2018, paper THPAK004, pp. 3207. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW012 | |
About • | paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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MOPGW020 | Numerical Calculation of Micro Bunching in BERLinPro Due to Space Charge and CSR Effects | 116 |
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Funding: Work supported by the German Bundesministerium für Bildung und Forschung, Land Berlin and grants of the Helmholtz Association BERLinPro is an Energy Recovery Linac Project, currently being set up at the Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany. BERLinPro is a small demonstrator for ERL technology and applications. Due to the low energy of 50, resp. 32MeV, space charge plays a dominant role in the beam dynamics. Micro-bunching, due to unavoidable shot noise from the cathode in combination with space charge, is seen in the merger as well as in the recirculator. Coherent synchrotron radiation (CSR) can amplify this bunching, as well as micro-bunching can enhance CSR losses. With the release of OPAL 2.0** in May 2018, for the first time, an open source, highly parallel tracking code is available, that is capable of numerically calculating both effects, space charge and CSR, simultaneously. The calculations are compared to earlier results*, that used analytical formulas on tracked, space charge dominated bunches. * "On space charge driven microbunching instability in BERLinPro", PhD thesis, S.D.Rädel, Humboldt Universität zu Berlin, 2017 ** http://amas.web.psi.ch/docs/opal/opaluserguide-2.0.0.pdf |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW020 | |
About • | paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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MOPGW021 | Symplectic Tracking for the Robinson Wiggler | 120 |
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A Robinson wiggler (RW) is considered to be installed in the Metrology Light Source (MLS) to lengthen the bunch and improve the Touschek lifetime by manipulating the damping partitions. Symplectic tracking is crucial to study the impact of the nonlinear field components introduced by the Robinson wiggler. This paper introduces a tracking method based on an implicit symplectic integrator to solve the exact Hamiltonian equations of particle motion in the wiggler. In addition, a numerical generating function method is implemented as an approach to realize fast tracking. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW021 | |
About • | paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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MOPGW031 | Analysis and Correction for the Effect of Multipoles with Skewed Errors on IP Beam Dynamics in SuperKEKB | 159 |
SUSPFO039 | use link to see paper's listing under its alternate paper code | |
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The beam dynamics at the interaction point (IP) in the accelerators which has the nano-beam scheme like as SuperKEKB is extremely sensitive for skewed error of final focusing magnets (QCS). As proceeding the beta squeezing in the interaction region (IR), the effect of optics aberrations at IP is enhanced. In the SuperKEKB Phase-2 commissioning, there was the problem come from skewed quadrupole fields in IR. The dominant skew parameters ‘‘R" for this problem is very hard to see directly by using beam position monitors, thus it was corrected by scanning R parameters. In the next commissioning Phase-3 which is just before the operation with the Belle II experiment, it is planned that the IP beta squeezing is going forward to design parameters which is smaller than it achieved in Phase-2 by the factor of 4 (for horizontal beta) and 10 (for vertical beta). Hence the effect of skew error will be considerable larger and it is estimated that skew sextupoles will emerge as a serious cause for the aberration from the orbit. This report is the study of analysis and correction results for the effect of QCS skewed errors in the SuperKEKB commissioning. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW031 | |
About • | paper received ※ 19 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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MOPGW041 | Transverse Profile Shaping of a Charged-Particle Beam using Multipole Magnets - Formation of Hollow Beams - | 184 |
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The use of multipole magnets enables us to shape the transverse profile of a charged-particle beam into various ones that can never be realized through linear beam optics. To date, the formation of a large-area beam with a uniform transverse intensity distribution has been actually realized using octupole magnets in several accelerator facilities. In this presentation, we demonstrate the formation of different beam profiles using multipole magnets rather than existing rectangular uniform beams. Results of tracking simulations and beam-formation experiments will be shown on the formation of clear-cut beams with different cross-sectional shapes, depending on the order and strength of applied multipole magnets. The dynamic behavior of a beam focused with multipole magnets is also investigated theoretically to better understand the numerical and experimental results. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW041 | |
About • | paper received ※ 19 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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MOPGW045 | A Fast Method for Multi-Objective Nonlinear Dynamics Optimization of a Storage Ring | 190 |
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Multi-objective evolutionary algorithms (MOEAs), including multi-objective genetic algorithm and particle swarm optimization algorithm, have been widely applied in the nonlinear dynamics optimization of storage ring light sources. In the optimization, the direct tracking of objectives, which are, for example, dynamic aperture (DA) and momentum aperture, is very time-consuming. We noticed that there is some positive correlation between on- and off-momentum nonlinear dynamics performances, which can be used to reduce the computation time when applying MOEAs. In this paper, a fast method is proposed, in which a strategy is introduced to speed up the process of optimizing nonlinear dynamics using MOEAs. Taking the SSRF storage ring as an example, on- and off-momentum DAs are optimized using MOEAs with and without the fast strategy, and then a comparison is made to demonstrate the fast method. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW045 | |
About • | paper received ※ 15 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019 | |
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MOPGW051 | Diffusion Map Analysis in High Energy Storage Ring Based e+/e− Collider | 203 |
SUSPFO074 | use link to see paper's listing under its alternate paper code | |
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Funding: Project 11775238 supported by NSFC In a very high energy e+/e− storage ring collider, e.g. Circular Electron Positron Collider (CEPC), the dynamic aperture is limited by the strong synchrotron radiation especially in the vertical direction. Some tracking results also shows that the beam lifetime does not correspond well to the dynamic aperture. Here we develop a method called diffusion map analysis, aiming to describe the beam distribution diffusion in transverse amplitude space by tracking less turns. The diffusion may come from quantum fluctuation of SR, beamstrahlung effect and nonlinearity. Comparing cases with different configuration of sextupoles, the diffusion map analysis presents good consistency with beam lifetime that needs much more turns of tracking. Constraints based on the diffusion map is applied to our dynamic aperture optimization, which could help us achieve enough long beam lifetime. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW051 | |
About • | paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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MOPGW059 | Dynamic Aperture Limitation in e+ e− Colliders due to Synchrotron Radiation in Quadrupoles | 221 |
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In a lepton storage ring of very high energy (e.g. in the e+e- Higgs factory) synchrotron radiation from quadrupoles constrains transverse dynamic aperture even in the absence of any magnetic nonlinearities. This was observed in tracking for LEP and the Future Circular e+e- Collider (FCC-ee). Synchrotron radiation in the quadrupoles modulates the particle energy at the double betatron frequency. Energy modulation varies transverse focusing strength at the same frequency and creates a parametric resonance of the betatron oscillations with unusual properties. It occurs at arbitrary betatron frequency and the magnitude of the parameter modulation of the betatron oscillation depends on the oscillation amplitude. Equilibrium between the radiation damping and the resonant excitation gives the boundary of the stable motion. Here we continue comparison of tracking results with analytical calculations of the parametric resonance. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW059 | |
About • | paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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MOPGW073 | Beam Manipulation Using Self-Induced Fields at the SwissFEL Injector | 266 |
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In the past years wakefield sources have been used to manipulate electron beams in accelerators. We recently installed corrugated structures for a total length of 2~m at the SwissFEL injector to test novel schemes for beam manipulations. We present simulations and early experimental results. We compare the model predictions with the measured data for the bunch energy losses and the kick factor, and show early results for the longitudinal phase space linearization and the production of current spikes. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW073 | |
About • | paper received ※ 09 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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MOPGW095 | Beam Dynamics Simulations with Crab Cavities in the SPS Machine | 342 |
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The LHC Upgrade, called High Luminosity LHC, aims to increase the integrated luminosity by a factor of 10. To achieve this, the project relies on a number of key innovative technologies, including the use of superconducting Crab Cavities with ultra-precise phase control for beam rotation. A set of prototype Crab Cavities has been recently installed in the second largest machine of CERN, the Super Proton Synchrotron (SPS), that operated as a test-bed from May to November of 2018. The tight LHC constraints call for axially non-symmetric cavity designs that introduce high order multipole components. Furthermore, the Crab Cavities in the presence of SPS non-linearities can affect the long term stability of the beam. This paper presents how the SPS dynamic aperture is affected for different cavity, machine and beam configurations. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW095 | |
About • | paper received ※ 06 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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MOPGW096 | Beam Dynamics in MBA Lattices with Different Chromaticity Correction Schemes | 346 |
SUSPFO115 | use link to see paper's listing under its alternate paper code | |
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Ultra-low emittance lattices are being studied for the future upgrade of the 2.75 GeV SOLEIL storage ring. The candidate baseline lattice was inspired by the ESRF-EBS-type Multi-Bend-Achromat (MBA) lattice, introducing a (-I) transformation to compensate the nonlinear impact of sextupoles thanks to the lattice symmetry and tight control of the betatron phase advance between sextupoles. Whilst the final performance is still being optimized, other types of lattices are being considered for SOLEIL: This includes the so-called High-Order Achromat (HOA) lattice. Though the (-I) scheme provides a large on-momentum transverse dynamic aperture in 4D, its off-momentum performance is rather limited. 6D studies reveal intrinsic off-momentum transverse oscillations which are likely to result from a nonlinear increase in path length. This contribution presents the effects from the inhomogeneous sextupole distribution in the (-I) scheme and compares them with the HOA lattice. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW096 | |
About • | paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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MOPGW105 | Preliminary Lattice Studies for the Single-Invariant Optics Experiment at the University of Maryland | 367 |
SUSPFO029 | use link to see paper's listing under its alternate paper code | |
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Funding: This work is supported through DOE-HEP Award DESC0010301 and NSF Award PHY1414681. A novel approach to transverse resonance suppression in next generation high-intensity accelerators is the use of nonlinear optical elements to induce large tune spreads which result in reduced responses to resonance driving perturbations*. In order to test this theory, we have built and characterized an octupole channel insert for use in the University of Maryland Electron Ring (UMER). This paper presents experimental lattice studies using a low space-charge intensity beam at an energy of 10keV with a beam current of ~150uA, tune depression < 0.005, and unnormalized RMS emittance of 4.3 mm-mr. We apply beam based measurement techniques in order to evaluate the quality of our single-invariant lattice and better understand the nonlinearities created by the octupole channel. * V. Danilov and S. Nagaitsev, Nonlinear accelerator lattices with one and two analytic invariants, PRSTAB, 13, 084002, 2010. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW105 | |
About • | paper received ※ 11 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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MOPGW107 | Study of Integrable and Quasi-Integrable Sextupole Lattice | 371 |
SUSPFO125 | use link to see paper's listing under its alternate paper code | |
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Funding: Funded through Center for Bright Beams, NSF award PHY-1549132 In order to maximize beam lifetime in circular particle accelerators, the nonlinear beam optics are optimized to maximize the dynamic aperture of the beam. The dynamic aperture (DA), which is a 6-D phase space volume of stable trajectories, depends on the strength of the nonlinearities in the machine, and is calculated via particle tracking. Current DA optimization processes include multi-objective genetic algorithm optimizers, and relies on minimizing the magnitudes of resonance driving terms (RDT), which are calculated from the nonlinear contribution to the one-turn-map. The process of searching through the parameter space for an ideal combination that maximizes DA is computationally strenuous. By setting up the sextupole channel such that it is resembles a symplectic integrator of a smooth Hamiltonian, with only a few sextupoles we are able to closely reproduce phase space trajectories of a smooth Hamiltonian up to the hyperbolic point. No chaos and resonances are observed if phase advance per one sextupole magnet in the channel does not exceed ~0.12x2 pi. Therefore, an important property of the suggested approach is the intrinsic elimination of the resonances, and minimization of corresponding RDTs. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW107 | |
About • | paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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MOPGW113 | Experimental Demonstration of the Henon-Heiles Quasi-Integrable System at IOTA | 386 |
SUSPFO126 | use link to see paper's listing under its alternate paper code | |
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Funding: Work supported by National Science Foundation award PHY-1549132, the Center for Bright Beams. Fermi Research Alliance operates Fermilab under Contract DE-AC02-07CH11359 with the US Dept. of Energy. The Integrable Optics Test Accelerator is a research electron and proton storage ring recently commissioned at the Fermilab Accelerator Science and Technology facility. Its research program is focused on testing novel techniques for improving beam stability and quality, notably the concept of non-linear integrable optics. In this paper, we report the first results of experimental investigation of a quasi-integrable transverse focusing system with one invariant of motion, a Henon-Heiles type system implemented with octupole magnets. Good agreement with simulations is demonstrated on key parameters of achievable tune spread and dynamic aperture preservation. Resilience to perturbations and imperfections in the lattice is explored. We conclude by outlining future research plans and discussing applicability to future high intensity accelerators. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW113 | |
About • | paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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MOPGW125 | Lossless Crossing of 1/2 Resonance Stopband by Synchrotron Oscillations | 410 |
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Funding: DOE under contract No.DE-AC02- 98CH10886 Modern high performance circular accelerators require sophisticated corrections of nonlinear lattices. The beam betatron tune footprint may cross many resonances, reducing dynamic aperture and causing particle loss. However, if particles cross a resonance reasonably fast, the beam deterioration may be minimized. In this paper, we present the experiments with the beam passing through a half-integer resonance stopband via chromatic tune modulation by exciting synchrotron oscillations. This is the first time that beam dynamics have been kept under precise control while the beam crosses a half-integer resonance. Our results convincingly demonstrate that particles can cross the half-integer resonance without being lost if the passage is reasonably fast and the resonance stopband is sufficiently narrow. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW125 | |
About • | paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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MOPMP053 | Numerical Optimization of DC Wire Compensation in HL-LHC | 570 |
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The electromagnetic field generated from a set of DC wires parallel to the beam opens the path to the compensation of the beam-beam long-range (BBLR) interactions for the future operation of large hadron colliders, in particular for the upcoming High Luminosity upgrade of the Large Hadron Collider (HL-LHC). The effectiveness and simplicity of a current carrying wire are critical for overcoming some technical constraints of the machine. In order to better understand the potential of this device for the HL-LHC, various simulation studies are presented. The different observables are the dynamic aperture and the frequency analysis. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP053 | |
About • | paper received ※ 03 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019 | |
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FRXPLS1 |
Symplectic Period Three Implies Chaos | |
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This invited talk describes a new concept of nonlinear dynamics that expands the classic work of Li and Yorke "Period Three Implies Chaos" to certain categories of symplectic maps. The theoretical classification of this type of chaos in accelerator systems may lead to the development of new control and feedback methods as seen similarly in fluid dynamics, and advance to experimental investigation at the Integrable Optics Test Accelerator at Fermilab.
* G. Rega, S. Lenci, and J.M.T Thompson, "Controlling Chaos: The OGY Method…", in "Nonlinear Dynamics and Chaos: Advances and Perspectives. Understanding Complex Systems". Springer, Berlin, 2010. |
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Slides FRXPLS1 [4.049 MB] | ||
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