IPAC2018 - List of Keywords (wiggler)

Paper	Title	Other Keywords	Page
MOPMF002	Pre-Booster Ring Considerations for the FCC e⁺e⁻ Injector	booster, emittance, damping, extraction	83
	O. Etisken Ankara University, Faculty of Sciences, Ankara, Turkey F. Antoniou, Y. Papaphilippou CERN, Geneva, Switzerland A.K. Çiftçi Izmir University of Economics, Balçova/Izmir, Turkey
	The FCC-e⁺e⁻ injector complex needs to produce and to transport a high-intensity e⁺/e⁻ beam at a fast repetition rate for topping up the collider at its collision energy. Two different options are under consideration as pre-accelerator before the bunches are transferred to the high-energy booster: using the existing SPS and a completely new ring. The purpose of this paper is to explore the needs and parameters of the existing SPS and the conceptual design of an alternative accelerator ring with injection and extraction energies of 6 and 20 GeV, respectively. In this study, the basic parameters of both choices are established, including the optics design and layout updates. Consideration for non-linear dynamics optimization and the impact of intra beam scattering are also presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF002
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TUPMF006	Pulsed Wire Measurements of a High Field Gradient Quadrupole Wiggler	quadrupole, alignment, laser, wakefield	1257
	M. Kasa, A. Zholents ANL, Argonne, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. Alignment of the quadrupoles in a quadrupole wiggler to sub micrometer precision is required for the collinear wakefield accelerator that is under consideration at Argonne National Laboratory for a compact Free-Electron Laser [1]. The pulsed wire measurement method is the only technique that we are aware of that allows for sub micrometer precision and the ability to distinguish between the various quadrupoles within the wiggler. A one period prototype wiggler was manufactured and subsequently measured using the pulsed wire technique. The goal of the measurements was to verify that the magnetic centers of each quadrupole could be located and aligned to each other within the required precision. The method and results are described. [1] A. Zholents, et al., "A preliminary design of the collinear dielectric wakefield accelerator", Nucl. Instrum. Meth. A829 (2016) 190-193.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF006
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TUPMF010	A Conceptual Design of a Compact Wakefield Accelerator for a High Repetition Rate Multi User X-ray Free-Electron Laser Facility	wakefield, electron, GUI, quadrupole	1266
	A. Zholents, D.S. Doran, W.G. Jansma, M. Kasa, R. Kustom, J.G. Power, N.O. Strelnikov, K.J. Suthar, E. Trakhtenberg, I. Vasserman, G.J. Waldschmidt, J.Z. Xu ANL, Argonne, Illinois, USA S. Baturin Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA H. Perez IIT, Chicago, Illinois, USA
	Funding: Supported by U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357 A preliminary design of a collinear wakefield accelerator is described. It is assumed that the array of such accelerators will play a central role in a free-electron laser-based x-ray user facility under consideration at Argonne National Laborator [1].
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF010
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TUPMF072	Microwave Instability and Energy Spread Measurement via Vertical Dispersion Bump in PETRA III	emittance, experiment, undulator, quadrupole	1427
	Y.-C. Chae, D. Dzhingaev, M. Ebert, G. Falkenberg, J. Keil, G. Kube, G.K. Sahoo, M. Sprung, R. Wanzenberg, F. Westermeier DESY, Hamburg, Germany A.I. Novokshonov TPU, Tomsk, Russia
	The recent measurement of bunch length versus current indicated that the longitudinal impedance (Z/n) is 0.15 Ω in close agreement with the impedance model. Naive application of Keil-Schnell criteria predicts the threshold of microwave instability at 0.25 mA. Since the single bunch intensity is in the range of 0.2-2.5 mA depending on the fill-pattern of PETRA III, we expect to observe the fill-pattern dependent energy spread according to the theory. However, the 3rd generation light sources comparable to PETRA III often reported the observation which was much greater than the theoretical one. In order to induce the beam size variation we had used skew quadrupoles to generate the dispersion in vertical plane. In particular we made dispersion bump at the undulator sector so that we were able to use the X-ray optics for the precise determination of small vertical beam size. In this paper we report the experimental setup and measurement data with the estimate on the instability threshold. We also report the vertical emittance and energy spread based on the X-ray beam size measurement as well as the RF signal which was excited by the beam at the longitudinal feedback cavity. K. Balewski, R. Wanzenberg, "OBSERVATION OF INTENSITY DEPENDENT SINGLE BUNCH EFFECTS AT THE SYNCHROTRON LIGHT SOURCE PETRA III", Proc. of IPAC2011, p. 730.
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TUPMF083	Influence of Intrabeam Scattering on the Emittance of PETRA III	emittance, scattering, damping, synchrotron	1463
	J. Keil, G. Kube, G.K. Sahoo, R. Wanzenberg DESY, Hamburg, Germany
	PETRA~III is a 6 GeV hard X-ray synchrotron radiation source at DESY in Hamburg (Germany) and is in user operation since~2010. The natural emittance of PETRA III is extremely low with 1.3 nm*rad and the coupling is typically less than 1%. PETRA III is operated with a beam current of 100 mA using two different filling modes: a continuous mode with 960 bunches and a timing mode with 40 bunches. It has been observed that the horizontal emittance depends on the filling pattern and is in timing mode slightly larger compared to the emittance in the continuous mode. Despite the high energy of 6 GeV intrabeam scattering contributes for a slight emittance growth due to the small natural emittance and coupling of the machine. The increase of the emittance as a function of the single bunch current has been measured by using different filling patterns at a fixed beam current of 100 mA. The measurements of the emittance and the lifetime as a function of the single bunch current will be compared with theoretical expectations of the emittance growth due to intrabeam scattering and the Touschek lifetime.
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WEXGBE2	Compensation of Insertion Device Induced Emittance Variations in Ultralow Emittance Storage Rings	emittance, lattice, 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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WEPML059	Status of the SuperKEKB Vacuum System in the Phase-2 Commissioning	MMI, vacuum, electron, permanent-magnet	2833
	Y. Suetsugu, H. Hisamatsu, T. Ishibashi, K. Kanazawa, K. Shibata, M. Shirai, S. Terui KEK, Ibaraki, Japan
	The SuperKEKB is an electron-positron collider with asymmetric energies in KEK aiming an extremely high luminosity of 8.0·10³⁵ /cm²/s. In the Phase-1 commissioning from February to June, 2016, the vacuum system of the main ring worked well as a whole at stored beam currents of approximately 1 A. However, several problems were found for the future commissioning, and various countermeasures were taken against these problems during the shutdown period before starting the Phase-2 commissioning. For example, permanent magnets were placed around the beam pipe to suppress the electron cloud effect in the positron ring. Other than these works, new beam pipes for the collision point, the super-conducting final focusing magnets and the positron beam injection region were installed in the main ring. Additional six beam collimators were installed for reducing background noise of the particle detector. Furthermore, the vacuum system for new damping ring for the positron beam was constructed. Reported here will be the present status of the vacuum system of the main ring, and major results of the countermeasures taken prior to the Phase-2 commissioning.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML059
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WEPML071	Superconducting 16-Pole Wiggler for Beijing Electron-Positron Collider II	vacuum, impedance, collider, positron	2853
	M.X. Li, X.J. Bian, F.S. Chen, W. Chen, X.J. Sun, H. Wang, J.L. Wang, N. Wang, M.F. Xu, X.C. Yang IHEP, Beijing, People's Republic of China
	A superconducting 16-pole 2.6T wiggler with period 170mm of The High-Energy Photon Source and the Test Facility Project (HEPS-TF) designed and fabricating in the Institute of High Energy Physics (IHEP) in China is described. This wiggler will be installed in Beijing Electron-Positron Collider II (BEPCII). The main parameters and structure of the wiggler are presented. Besides, some vertical testing results are involved.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML071
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THPAF031	A PETRA IV Lattice based on Hybrid Seven Bend Achromats	emittance, lattice, damping, 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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THPAF086	Beam Dynamics Simulations for Operating a Robinson Wiggler at the MLS	optics, operation, dynamic-aperture, storage-ring	3189
	J. Li, J. Feikes, M. Ries HZB, Berlin, Germany T. Tydecks CERN, Geneva, Switzerland
	A Robinson wiggler is planned to be installed in the storage ring of the Metrology Light Source (the MLS). The Robison wiggler (RW) is a device consisting of a chain of combined-function magnets (CFMs), intended to manipulate the damping partition numbers and thus adjust the longitudinal emittance. The objective is to lengthen the bunch in order to improve the Touschek lifetime. However, the nonlinear perturbation of the beam dynamics due to the Robinson wiggler could limit the achievable improvement. Therefore, a symplectic method of modeling the wiggler has been established to study these nonlinear effects. Optimized solutions have been developed for both the ramping procedure and the future daily operation of the wiggler and are presented in this paper.
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THPAK029	Studies of the Micro-Bunching Instability in the Presence of a Damping Wiggler	damping, radiation, synchrotron, bunching	3273
	M. Brosi, A. Bernhard, J. Gethmann, B. Kehrer, A.-S. Müller, A.I. Papash, P. Schreiber, P. Schönfeldt, J.L. Steinmann KIT, Karlsruhe, Germany
	Funding: Funded by BMBF (grant: 05K16VKA) & Helmholtz (contract: VH-NG-320). Supported by the Helmholtz International Research School for Teratronics & Karlsruhe School of Elementary and Astroparticle Physics. At the KIT storage ring KARA (KArlsruhe Research Accelerator), the momentum compaction factor can be reduced leading to natural bunch lengths in the ps range. Due to the high degree of longitudinal compression the micro-bunching instability arises. During this longitudinal instability the bunches emit bursts of intense coherent synchrotron radiation in the THz frequency range caused by the complex longitudinal dynamics. The temporal pattern of the emitted bursts depends on given machine parameters, like momentum compaction factor, acceleration voltage, and damping time. In this paper the influence of the damping time is studied by utilizing the CLIC damping wiggler prototype installed in KARA as well as by simulations using the Vlasov-Fokker-Planck solver Inovesa.
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THPMF070	Non-Linear Optics and Low Alpha Operation at the Storage Ring KARA at KIT	operation, octupole, resonance, injection	4235
	A.I. Papash, E. Blomley, M. Brosi, J. Gethmann, B. Kehrer, A.-S. Müller, M. Schuh, P. Schönfeldt, J.L. Steinmann KIT, Karlsruhe, Germany
	The storage ring Karlsruhe Research Accelerator (KARA) at KIT operate in a wide energy range from 0.5 to 2.5 GeV. Different non-linear effects, in particular, residual octupole components of the magnetic field of the CATACT wiggler at high field level (2.5 T), proximity of the working point to a vertical sextupole resonance Qy=8/3 and weak coupling octupole resonance 2Qx+2Qy=19, high chromaticity, etc. decrease the beam life time. This is because of the reduced dynamic aperture and momentum acceptance for off-momentum particles. A new operation point at high vertical tune Qy=2.81 was tested. For this, injection and ramping tables have been modified. First the values were optimized by simulations, then during beam tests, to minimize betatron tune shaking during beam-energy ramps. It stabilized high-current beams by the fast-feedback system the whole process: injection at 0.5 GeV, ramping, and operation at 1.3 GeV cycles. It essentially improved life time and beam current. In addition, new low-alpha tables have been created and tested, resulting in the reduction of the momentum compaction factor to 10^-4. Short bunch operation at 0.5GeV injection energy was also tested successfully.
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THPMF086	Reliability Improvement on Wiggler Period Averaging Approximation	FEL, simulation, laser, plasma	4281
	K. Hwang, J. Qiang LBNL, Berkeley, California, USA
	Funding: US Department of Energy under Contract no. DEAC02-05CH11231 As the wiggler period averaging is subject to reliability issue, many efforts on FEL codes without such approximations are made at the cost of heavier computation loads. However, efforts toward increasing the reliability of such approximation are few. In this report, we present a new capability of IMPACT code suite based on such approximation with the addition of perturbative corrections to wiggler period averaging error.
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THPMK013	A Wiggler Magnet Design for the TPS	emittance, photon, electron, undulator	4317
	J.C. Jan, Y.L. Chu, C.-S. Hwang, F.H. Tseng NSRRC, Hsinchu, Taiwan
	The Taiwan Photon Source (TPS) at the National Synchrotron Radiation Research Center (NSRRC) is an advanced photon source facility operating at an electron energy of 3 GeV. Ten insertion devices (IDs) have been installed in phase-I during 2015. Recently, plans and designs for several phase-II IDs including In-vacuum Undulators (IU), Cryogenic Undulators (CU), Elliptical Polarization Undulators (EPU) and Wiggler magnets are pursued at NSRRC. These IDs are expected to be installed before 2020. In particular, a room temperature wiggler magnet with 100 mm period length (W100), will be designed and installed for phase-II. The field strength of the W100 is 1.8 T and the number of main periods is four. It is designed to generate 5-50 keV photons for the microscopy beam line. The magnetic design and photon characteristics of the W100 together with its effects on the stored beam will be discussed in this paper.
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THPMK083	Self-Modulation of a Relativistic Electron Beam in a Wiggler	electron, laser, radiation, free-electron-laser	4492
	J.P. MacArthur Stanford University, Stanford, California, USA J.P. Duris, Z. Huang, A. Marinelli, Z. Zhang SLAC, Menlo Park, California, USA
	Users at x-ray free-electron laser (FEL) facilities have shown strong interest in using single spike, coherent x-ray pulses to probe attosceond dynamics in atoms and molecules. Sub-femtosecond soft x-ray pulses may be obtained from an electron beam that has been modulated in a wiggler resonant with an external laser, the enhanced-SASE technique. We discuss a new way to produce this energy modulation, wherein the external laser is replaced by coherent radiation from the current spike on the tail of the electron beam. We calculate the modulation expected in a wiggler from both a single frequency perspective and a coherent synchrotron radiation (CSR) perspective.
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Paper

Title

Other Keywords

Page

MOPMF002

Pre-Booster Ring Considerations for the FCC e⁺e⁻ Injector

booster, emittance, damping, extraction

83

O. Etisken
Ankara University, Faculty of Sciences, Ankara, Turkey
F. Antoniou, Y. Papaphilippou
CERN, Geneva, Switzerland
A.K. Çiftçi
Izmir University of Economics, Balçova/Izmir, Turkey

The FCC-e⁺e⁻ injector complex needs to produce and to transport a high-intensity e⁺/e⁻ beam at a fast repetition rate for topping up the collider at its collision energy. Two different options are under consideration as pre-accelerator before the bunches are transferred to the high-energy booster: using the existing SPS and a completely new ring. The purpose of this paper is to explore the needs and parameters of the existing SPS and the conceptual design of an alternative accelerator ring with injection and extraction energies of 6 and 20 GeV, respectively. In this study, the basic parameters of both choices are established, including the optics design and layout updates. Consideration for non-linear dynamics optimization and the impact of intra beam scattering are also presented.

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TUPMF006

Pulsed Wire Measurements of a High Field Gradient Quadrupole Wiggler

quadrupole, alignment, laser, wakefield

1257

M. Kasa, A. Zholents
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
Alignment of the quadrupoles in a quadrupole wiggler to sub micrometer precision is required for the collinear wakefield accelerator that is under consideration at Argonne National Laboratory for a compact Free-Electron Laser [1]. The pulsed wire measurement method is the only technique that we are aware of that allows for sub micrometer precision and the ability to distinguish between the various quadrupoles within the wiggler. A one period prototype wiggler was manufactured and subsequently measured using the pulsed wire technique. The goal of the measurements was to verify that the magnetic centers of each quadrupole could be located and aligned to each other within the required precision. The method and results are described.
[1] A. Zholents, et al., "A preliminary design of the collinear dielectric wakefield accelerator", Nucl. Instrum. Meth. A829 (2016) 190-193.

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TUPMF010

A Conceptual Design of a Compact Wakefield Accelerator for a High Repetition Rate Multi User X-ray Free-Electron Laser Facility

wakefield, electron, GUI, quadrupole

1266

A. Zholents, D.S. Doran, W.G. Jansma, M. Kasa, R. Kustom, J.G. Power, N.O. Strelnikov, K.J. Suthar, E. Trakhtenberg, I. Vasserman, G.J. Waldschmidt, J.Z. Xu
ANL, Argonne, Illinois, USA
S. Baturin
Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA
H. Perez
IIT, Chicago, Illinois, USA

Funding: Supported by U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357
A preliminary design of a collinear wakefield accelerator is described. It is assumed that the array of such accelerators will play a central role in a free-electron laser-based x-ray user facility under consideration at Argonne National Laborator [1].

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TUPMF072

Microwave Instability and Energy Spread Measurement via Vertical Dispersion Bump in PETRA III

emittance, experiment, undulator, quadrupole

1427

Y.-C. Chae, D. Dzhingaev, M. Ebert, G. Falkenberg, J. Keil, G. Kube, G.K. Sahoo, M. Sprung, R. Wanzenberg, F. Westermeier
DESY, Hamburg, Germany
A.I. Novokshonov
TPU, Tomsk, Russia

The recent measurement of bunch length versus current indicated that the longitudinal impedance (Z/n) is 0.15 Ω in close agreement with the impedance model*. Naive application of Keil-Schnell criteria predicts the threshold of microwave instability at 0.25 mA. Since the single bunch intensity is in the range of 0.2-2.5 mA depending on the fill-pattern of PETRA III, we expect to observe the fill-pattern dependent energy spread according to the theory. However, the 3rd generation light sources comparable to PETRA III often reported the observation which was much greater than the theoretical one. In order to induce the beam size variation we had used skew quadrupoles to generate the dispersion in vertical plane. In particular we made dispersion bump at the undulator sector so that we were able to use the X-ray optics for the precise determination of small vertical beam size. In this paper we report the experimental setup and measurement data with the estimate on the instability threshold. We also report the vertical emittance and energy spread based on the X-ray beam size measurement as well as the RF signal which was excited by the beam at the longitudinal feedback cavity.
* K. Balewski, R. Wanzenberg, "OBSERVATION OF INTENSITY DEPENDENT SINGLE BUNCH EFFECTS AT THE SYNCHROTRON LIGHT SOURCE PETRA III", Proc. of IPAC2011, p. 730.

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TUPMF083

Influence of Intrabeam Scattering on the Emittance of PETRA III

emittance, scattering, damping, synchrotron

1463

J. Keil, G. Kube, G.K. Sahoo, R. Wanzenberg
DESY, Hamburg, Germany

PETRA~III is a 6 GeV hard X-ray synchrotron radiation source at DESY in Hamburg (Germany) and is in user operation since~2010. The natural emittance of PETRA III is extremely low with 1.3 nm*rad and the coupling is typically less than 1%. PETRA III is operated with a beam current of 100 mA using two different filling modes: a continuous mode with 960 bunches and a timing mode with 40 bunches. It has been observed that the horizontal emittance depends on the filling pattern and is in timing mode slightly larger compared to the emittance in the continuous mode. Despite the high energy of 6 GeV intrabeam scattering contributes for a slight emittance growth due to the small natural emittance and coupling of the machine. The increase of the emittance as a function of the single bunch current has been measured by using different filling patterns at a fixed beam current of 100 mA. The measurements of the emittance and the lifetime as a function of the single bunch current will be compared with theoretical expectations of the emittance growth due to intrabeam scattering and the Touschek lifetime.

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WEXGBE2

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

emittance, lattice, 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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WEPML059

Status of the SuperKEKB Vacuum System in the Phase-2 Commissioning

MMI, vacuum, electron, permanent-magnet

2833

Y. Suetsugu, H. Hisamatsu, T. Ishibashi, K. Kanazawa, K. Shibata, M. Shirai, S. Terui
KEK, Ibaraki, Japan

The SuperKEKB is an electron-positron collider with asymmetric energies in KEK aiming an extremely high luminosity of 8.0·10³⁵ /cm²/s. In the Phase-1 commissioning from February to June, 2016, the vacuum system of the main ring worked well as a whole at stored beam currents of approximately 1 A. However, several problems were found for the future commissioning, and various countermeasures were taken against these problems during the shutdown period before starting the Phase-2 commissioning. For example, permanent magnets were placed around the beam pipe to suppress the electron cloud effect in the positron ring. Other than these works, new beam pipes for the collision point, the super-conducting final focusing magnets and the positron beam injection region were installed in the main ring. Additional six beam collimators were installed for reducing background noise of the particle detector. Furthermore, the vacuum system for new damping ring for the positron beam was constructed. Reported here will be the present status of the vacuum system of the main ring, and major results of the countermeasures taken prior to the Phase-2 commissioning.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML059

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WEPML071

Superconducting 16-Pole Wiggler for Beijing Electron-Positron Collider II

vacuum, impedance, collider, positron

2853

M.X. Li, X.J. Bian, F.S. Chen, W. Chen, X.J. Sun, H. Wang, J.L. Wang, N. Wang, M.F. Xu, X.C. Yang
IHEP, Beijing, People's Republic of China

A superconducting 16-pole 2.6T wiggler with period 170mm of The High-Energy Photon Source and the Test Facility Project (HEPS-TF) designed and fabricating in the Institute of High Energy Physics (IHEP) in China is described. This wiggler will be installed in Beijing Electron-Positron Collider II (BEPCII). The main parameters and structure of the wiggler are presented. Besides, some vertical testing results are involved.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML071

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THPAF031

A PETRA IV Lattice based on Hybrid Seven Bend Achromats

emittance, lattice, damping, 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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THPAF086

Beam Dynamics Simulations for Operating a Robinson Wiggler at the MLS

optics, operation, dynamic-aperture, storage-ring

3189

J. Li, J. Feikes, M. Ries
HZB, Berlin, Germany
T. Tydecks
CERN, Geneva, Switzerland

A Robinson wiggler is planned to be installed in the storage ring of the Metrology Light Source (the MLS). The Robison wiggler (RW) is a device consisting of a chain of combined-function magnets (CFMs), intended to manipulate the damping partition numbers and thus adjust the longitudinal emittance. The objective is to lengthen the bunch in order to improve the Touschek lifetime. However, the nonlinear perturbation of the beam dynamics due to the Robinson wiggler could limit the achievable improvement. Therefore, a symplectic method of modeling the wiggler has been established to study these nonlinear effects. Optimized solutions have been developed for both the ramping procedure and the future daily operation of the wiggler and are presented in this paper.

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THPAK029

Studies of the Micro-Bunching Instability in the Presence of a Damping Wiggler

damping, radiation, synchrotron, bunching

3273

M. Brosi, A. Bernhard, J. Gethmann, B. Kehrer, A.-S. Müller, A.I. Papash, P. Schreiber, P. Schönfeldt, J.L. Steinmann
KIT, Karlsruhe, Germany

Funding: Funded by BMBF (grant: 05K16VKA) & Helmholtz (contract: VH-NG-320). Supported by the Helmholtz International Research School for Teratronics & Karlsruhe School of Elementary and Astroparticle Physics.
At the KIT storage ring KARA (KArlsruhe Research Accelerator), the momentum compaction factor can be reduced leading to natural bunch lengths in the ps range. Due to the high degree of longitudinal compression the micro-bunching instability arises. During this longitudinal instability the bunches emit bursts of intense coherent synchrotron radiation in the THz frequency range caused by the complex longitudinal dynamics. The temporal pattern of the emitted bursts depends on given machine parameters, like momentum compaction factor, acceleration voltage, and damping time. In this paper the influence of the damping time is studied by utilizing the CLIC damping wiggler prototype installed in KARA as well as by simulations using the Vlasov-Fokker-Planck solver Inovesa.

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THPMF070

Non-Linear Optics and Low Alpha Operation at the Storage Ring KARA at KIT

operation, octupole, resonance, injection

4235

A.I. Papash, E. Blomley, M. Brosi, J. Gethmann, B. Kehrer, A.-S. Müller, M. Schuh, P. Schönfeldt, J.L. Steinmann
KIT, Karlsruhe, Germany

The storage ring Karlsruhe Research Accelerator (KARA) at KIT operate in a wide energy range from 0.5 to 2.5 GeV. Different non-linear effects, in particular, residual octupole components of the magnetic field of the CATACT wiggler at high field level (2.5 T), proximity of the working point to a vertical sextupole resonance Qy=8/3 and weak coupling octupole resonance 2Qx+2Qy=19, high chromaticity, etc. decrease the beam life time. This is because of the reduced dynamic aperture and momentum acceptance for off-momentum particles. A new operation point at high vertical tune Qy=2.81 was tested. For this, injection and ramping tables have been modified. First the values were optimized by simulations, then during beam tests, to minimize betatron tune shaking during beam-energy ramps. It stabilized high-current beams by the fast-feedback system the whole process: injection at 0.5 GeV, ramping, and operation at 1.3 GeV cycles. It essentially improved life time and beam current. In addition, new low-alpha tables have been created and tested, resulting in the reduction of the momentum compaction factor to 10^-4. Short bunch operation at 0.5GeV injection energy was also tested successfully.

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THPMF086

Reliability Improvement on Wiggler Period Averaging Approximation

FEL, simulation, laser, plasma

4281

K. Hwang, J. Qiang
LBNL, Berkeley, California, USA

Funding: US Department of Energy under Contract no. DEAC02-05CH11231
As the wiggler period averaging is subject to reliability issue, many efforts on FEL codes without such approximations are made at the cost of heavier computation loads. However, efforts toward increasing the reliability of such approximation are few. In this report, we present a new capability of IMPACT code suite based on such approximation with the addition of perturbative corrections to wiggler period averaging error.

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THPMK013

A Wiggler Magnet Design for the TPS

emittance, photon, electron, undulator

4317

J.C. Jan, Y.L. Chu, C.-S. Hwang, F.H. Tseng
NSRRC, Hsinchu, Taiwan

The Taiwan Photon Source (TPS) at the National Synchrotron Radiation Research Center (NSRRC) is an advanced photon source facility operating at an electron energy of 3 GeV. Ten insertion devices (IDs) have been installed in phase-I during 2015. Recently, plans and designs for several phase-II IDs including In-vacuum Undulators (IU), Cryogenic Undulators (CU), Elliptical Polarization Undulators (EPU) and Wiggler magnets are pursued at NSRRC. These IDs are expected to be installed before 2020. In particular, a room temperature wiggler magnet with 100 mm period length (W100), will be designed and installed for phase-II. The field strength of the W100 is 1.8 T and the number of main periods is four. It is designed to generate 5-50 keV photons for the microscopy beam line. The magnetic design and photon characteristics of the W100 together with its effects on the stored beam will be discussed in this paper.

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THPMK083

Self-Modulation of a Relativistic Electron Beam in a Wiggler

electron, laser, radiation, free-electron-laser

4492

J.P. MacArthur
Stanford University, Stanford, California, USA
J.P. Duris, Z. Huang, A. Marinelli, Z. Zhang
SLAC, Menlo Park, California, USA

Users at x-ray free-electron laser (FEL) facilities have shown strong interest in using single spike, coherent x-ray pulses to probe attosceond dynamics in atoms and molecules. Sub-femtosecond soft x-ray pulses may be obtained from an electron beam that has been modulated in a wiggler resonant with an external laser, the enhanced-SASE technique. We discuss a new way to produce this energy modulation, wherein the external laser is replaced by coherent radiation from the current spike on the tail of the electron beam. We calculate the modulation expected in a wiggler from both a single frequency perspective and a coherent synchrotron radiation (CSR) perspective.

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