IPAC2021 - Classification: MC2: Photon Sources and Electron Accelerators / A04 Circular Accelerators

Paper	Title	Page
MOXA01	Commissioning and Restart of ESRF-EBS	1
	S.M. White, N. Carmignani, L.R. Carver, J. Chavanne, L. Farvacque, L. Hardy, J. Jacob, G. Le Bec, S.M. Liuzzo, T.P. Perron, Q. Qin, P. Raimondi, J.-L. Revol, K.B. Scheidt ESRF, Grenoble, France
	The ESRF operates a 6 GeV 4th generation light source, the ESRF-EBS. This storage ring is the first to implement the Hybrid Multi-Bend Achromat lattice (HMBA). The HMBA lattice provides a reduction of the horizontal emittance of approximately a factor 30 with respect to the former Double Bend Achromat (DBA) structure, considerably improving the brilliance and transverse coherence of the ESRF accelerator complex while maintaining large horizontal acceptance and excellent lifetime performance. In this report, the characteristics of the HMBA lattice will be reviewed and the beam commissioning results and first operation experience of the new ESRF storage ring will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOXA01
About •	paper received ※ 11 May 2021 paper accepted ※ 31 August 2021 issue date ※ 01 September 2021
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MOXA02	Status of the APS-U Project	7
	R.O. Hettel ANL, Lemont, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Sci- ence, Office of Basic Energy Sciences, under Contract No. DE-AC02- 06CH11357. The Advanced Photon Source Upgrade (APS-U) project at the Argonne National Laboratory will re-place the existing 7-GeV, 1.1-km circumference dou-ble bend storage ring lattice with a new 6-GeV hybrid 7BA lattice that will reduce horizontal electron emit-tance from 3 nm-rad to 42 pm-rad, including IBS ef-fects for 200-mA operation. With new optimized per-manent magnet and superconducting undulators, an increase in spectral brightness of two to three orders of magnitude in the 10-100 keV X-ray energy range will be realized. The project includes nine new high performance beamlines and fifteen enhanced beam-lines that will exploit the high brightness and coher-ence of the new facility. The project is in full swing, more than 50% complete by cost, and is on schedule for first beam sometime in mid-2024, a slip of 10 months from the original schedule due to the impact of COVID-19. Project status, challenges and outstanding issues will be discussed in this article.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOXA02
About •	paper received ※ 21 May 2021 paper accepted ※ 09 June 2021 issue date ※ 11 August 2021
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MOXA03	Sirius Commissioning Results and Operation Status	13
	L. Liu, M.B. Alves, A.C.S. Oliveira, X.R. Resende, F.H. de Sá LNLS, Campinas, Brazil
	Sirius is a 4th generation 3 GeV synchrotron light source that has just finalized the first commissioning phase at the Brazilian Center for Research in Energy and Materials (CNPEM) campus in Campinas, Brazil. This paper describes the main Accelerator Physics issues faced during the storage ring commissioning, methods that were used to work them out and the current operation status of the machine.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOXA03
About •	paper received ※ 20 May 2021 paper accepted ※ 10 June 2021 issue date ※ 16 August 2021
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MOPAB020	Improvements to the SLS Booster Synchrotron Performance Towards SLS 2.0	103
	J. Kallestrup, M. Aiba PSI, Villigen PSI, Switzerland
	The Swiss Light Source (SLS) storage ring will undergo a major upgrade to a multi-bend achromat lattice. The existing injector complex will be reused with few modifications. However, the SLS booster synchrotron has not been studied since the initial commissioning in years 2000-2001. We plan to apply an emittance exchange in the booster to lower the horizontal emittance, which is a critial parameter for the injection. Here, we present improvements to the SLS booster as a preparation for SLS 2.0 upgrade project. The vertical beam size is decreased by 50\% by the use of vertical orbit correctors without beam position monitors, leading also to suppression of vertical dispersion and a factor 10 reduction of the transverse coupling coefficient. The emittance exchange reflected these improvements in the horizontal emittance, achieving a factor of 9-10 reduction. Lastly, a fast head-tail instability limiting the injection rate into the storage ring is discovered and subsequently suppressed by correcting the chromaticities.
	Poster MOPAB020 [0.380 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB020
About •	paper received ※ 19 May 2021 paper accepted ※ 01 June 2021 issue date ※ 30 August 2021
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MOPAB035	Modified Lattice of the Compact Storage Ring in the cSTART Project at Karlsruhe Institute of Technology	159
	A.I. Papash, E. Bründermann, B. Härer, A.-S. Müller, R. Ruprecht, J. Schäfer, M. Schuh KIT, Karlsruhe, Germany
	A very large acceptance compact storage ring (VLA-cSR) is under design at the Institute for Beam Physics and Technology (IBPT) of the Karlsruhe Institute of Technology (KIT, Germany). The combination of a compact storage ring and a laser wakefield accelerator (LWFA) might be the basis for future compact light sources and advancing user facilities. Meanwhile, the post-LWFA beam should be adapted for storage and accumulation in a dedicated storage ring. Modified geometry and lattice of a VLA-cSR operating at 50 MeV energy range have been studied in detailed simulations. The main features of a new model are described here. The new design, based on 45° bending magnets, is suitable to store the post-LWFA beam with a wide momentum spread (1% to 2%) as well as ultra-short electron bunches in the fs range from the Ferninfrarot Linac- Und Test- Experiment (FLUTE). The DBA-FDF lattice with relaxed settings, split elements, and higher-order optics of tolerable strength allows improving the dynamic aperture to an acceptable level. This contribution discusses the lattice features in detail and different possible operation schemes of a VLA-cSR.
	Poster MOPAB035 [1.405 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB035
About •	paper received ※ 10 May 2021 paper accepted ※ 27 May 2021 issue date ※ 24 August 2021
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MOPAB038	Robustness Studies and First Commissioning Simulations for the SOLEIL Upgrade Lattice	171
	D. Amorim, A. Loulergue, L.S. Nadolski, R. Nagaoka SOLEIL, Gif-sur-Yvette, France
	Diffraction limited light sources will use very strong focusing elements to achieve their emittance goal. The beam will therefore be more sensitive to magnet field and alignment errors. Impact of errors on the lattice proposed for the SOLEIL upgrade was studied with the Accelerator Toolbox (AT) code. The performance achieved with the imperfect lattice will be presented. In particular the effect of girders misalignment was also accounted for. As the lattice uses a large number of permanent magnets for the beam bending as well as the focusing, challenges arise in terms of beam correction. The correctors and BPMs location and number will be investigated to maximize their efficiency, and corrector magnet strength required to obtain a closed orbit will be studied. The commissioning strategy, and in particular the method used to achieve the first turns and a stored beam in the machine will also be exposed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB038
About •	paper received ※ 19 May 2021 paper accepted ※ 31 May 2021 issue date ※ 16 August 2021
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MOPAB039	Amplitude-Dependent Shift of Betatron Tunes and Its Relation to Long-Term Circumference Variations at NSLS-II	175
	L.H. Yu, G. Bassi, Y. Hidaka, B. Podobedov, V.V. Smaluk, G.M. Wang, X. Yang BNL, Upton, New York, USA
	The comparison of amplitude tune dependence measured for NSLSII lattices with models indicated the large change of amplitude tune dependence over time apparently can not be solely explained by magnets variation or beta function changes, but it seems can be explained by energy changes. On the other hand, the energy change required by fitting with the amplitude tune dependence change is too large to be explained by the RF frequency change and the change of the sum of correctors in the period of the measurements. To explain this apparent contradiction, our analysis shows the long term storage ring circumference change can explain the apparent energy change. Our data indeed shows a seasonal change of the amplitude tune dependence over long term observation. This clearly also indicated a relation to long term closed orbit drift. Hence the current work indicates a new strategy to study how to use amplitude tune dependence as a guideline to analyze long term lattice parameter shifts and closed orbit drift, and improve the orbit and machine performance stability.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB039
About •	paper received ※ 09 May 2021 paper accepted ※ 26 May 2021 issue date ※ 26 August 2021
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MOPAB042	Beam Dynamics Investigation for a New Project of Compton Back Scattering Photon Source at NRNU MEPhI	186
	V.S. Dyubkov, I.A. Ashanin, M. Gusarova, Yu.D. Kliuchevskaia, M.V. Lalayan, S.M. Polozov, A.I. Pronikov, V.I. Rashchikov MEPhI, Moscow, Russia
	Funding: This project is supported by Russian Foundation for Basic Research, Grant no. 19-29-12036. The activities on physical models design of a compact monochromatic radiation source in the x-ray range based on inverse Compton scattering are started at NRNU MEPhI. There are comparison of two schemes of the photon source here: one of them is considered to be based on linac with variable energy of 20-60 MeV only and the other one is considered as accelerator complex where linac is supposed to be used as injector to medium size storage ring (energy up to 60 MeV). Preliminary results of linac structures and storage ring design as well as electron dynamics simulation are discussed
	Poster MOPAB042 [0.962 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB042
About •	paper received ※ 13 May 2021 paper accepted ※ 20 May 2021 issue date ※ 10 August 2021
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MOPAB043	Validation of APS-U Beam Dynamics Using 6-GeV APS Beam	189
	L. Emery, P.S. Kallakuri, R.R. Lindberg, A. Xiao ANL, Lemont, 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. Several beam measurements at the Advanced Photon Sources were done with a lowered-energy beam of 6 GeV in order to verify or validate calculation codes and some predictions for the APS-U. Though the APS lattice is obviously different from that of the APS-U some aspects of the beams at 6 GeV are similar, for example, the synchrotron radiation damping rate. At 6 GeV, one can also store more current and run with a higher rf bucket allowing the characterization of larger momentum aperture lattices. We report measurements (or plans of measurements) on general instabilities thresholds, lifetime, and other subtle effects. The important topic of ion instabilities at 6 GeV is covered in a separate paper by J. Calvey at this conference.
	Poster MOPAB043 [0.829 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB043
About •	paper received ※ 20 May 2021 paper accepted ※ 23 June 2021 issue date ※ 10 August 2021
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MOPAB044	Gas Bremsstrahlung Measurements in the Advanced Photon Source Storage Ring	193
	J.C. Dooling, A.R. Brill, J.R. Calvey ANL, Lemont, Illinois, USA
	Funding: Work supported by the U.S. D.O.E.,Office of Science, Office of Basic Energy Sciences, under contract number DE-AC02- 06CH11357. In the Advanced Photon Source Upgrade storage ring (SR), small-aperture vacuum chambers provide limited conductance for pumping. Non-evaporable getter (NEG) coatings will be used in the SR to support the vacuum. Ion pumps and cold-cathode gauges are typically located away from the vacuum chamber transporting the beam. Measuring gas bremsstrahlung (GB) photons in low-conductance chambers provides a method to determine the pressure at the beam location. We report on GB measurements made in the ID-25 beamline. A Pb:Glass calorimeter radiator generates Cherenkov radiation when high-energy photons cause pair-production within the glass. A photomultiplier tube converts the light pulses to electrical signals. Data was obtained during normal machine operations starting in January 2020. Data collection was facilitated using a 4-channel ITech Beam Loss Monitor FPGA that allows for control of thresholds and attenuation settings in both counting and pulse-height acquisition modes. Count rates and spectra were recorded for the three primary fill patterns typically used during SR operations as well as during gas injection experiments; results of these measurements will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB044
About •	paper received ※ 22 May 2021 paper accepted ※ 28 May 2021 issue date ※ 25 August 2021
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MOPAB045	Measurements and Simulations of High Charge Beam in the APS Booster	197
	J.R. Calvey, J.C. Dooling, K.C. Harkay, K.P. Wootton, C. Yao ANL, Lemont, Illinois, USA
	For the APS-Upgrade, swap-out injection will require the booster to support up to 17 nC bunch charge, several times what is used in the present APS. Booster injection efficiency drops sharply at high charge, and is the present bottleneck limiting high charge transport through the injectors. Particle tracking simulations have been used to understand what causes are limiting the injection efficiency, and to guide plans for improving it. In particular, bunch length blowup in the injected beam and beam loading in the RF cavities have been identified as the biggest factors. Simulations and measurements have also been done to characterize beam properties along the booster energy ramp. So far, a bunch charge of 12 nC has been successfully extracted from the booster.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB045
About •	paper received ※ 19 May 2021 paper accepted ※ 26 July 2021 issue date ※ 16 August 2021
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MOPAB046	Plan for Operating the APS-Upgrade Booster with a Frequency Sweep	201
	J.R. Calvey, T.G. Berenc, A.R. Brill, L. Emery, T. Fors, K.C. Harkay, T.J. Madden, N. Sereno, U. Wienands ANL, Lemont, Illinois, USA A. Gu UCB, Berkeley, California, USA
	The APS-Upgrade presents several challenging demands to the booster synchrotron. Swap-out injection requires the booster to capture a high charge bunch (up to 17 nC), accelerate it to 6 GeV, and maintain a low emittance at extraction for injection into the storage ring. To accommodate these conflicting demands, the RF frequency will be ramped between injection and extraction. However, the RF cavity tuners will remain static, which means the couplers will need to withstand a high reflected power at extraction. This paper presents a plan for a system that will meet the requirements for injection efficiency, extracted emittance, and equivalent power at the coupler. Results from tracking simulations and beam studies with a frequency ramp will also be shown.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB046
About •	paper received ※ 28 May 2021 paper accepted ※ 02 June 2021 issue date ※ 26 August 2021
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MOPAB047	A CAD Tool for Linear Optics Design: A Use Case Approach	205
	J. Bengtsson HZB, Berlin, Germany T.J.R. Nicholls, W.A.H. Rogers DLS, Oxfordshire, United Kingdom
	The formula relevant for linear optics design of synchrotrons are derived systematically from first principles, i.e., an exercise in Hamiltonian dynamics. Equipped with these, the relevant use cases are then captured; for a streamlined approach. To enable professionals, i.e., software engineers, to efficiently prototype & architect a CAD tool available to mechanical engineers since the mid-1960s. In other words, robust design of a modern synchrotron is an exercise in/pursuit of the art of Engineering-Science.
	Poster MOPAB047 [1.059 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB047
About •	paper received ※ 17 May 2021 paper accepted ※ 28 May 2021 issue date ※ 15 August 2021
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MOPAB049	Gyroresonant Acceleration of Electrons by an Axisymmetric Transverse Electric Field	213
	E.A. Orozco, O. Otero Olarte UIS, Bucaramanga, Colombia
	The acceleration of electrons using gyromagnetic autoresonance consist on the sustaint of the electron cyclotron resonant condition through of a magnetic field which increase on time, this scheme was propose by K. S. Golovanivsky. In this work, we considerer the gyroresonant acceleration of electrons using an axisymmetric transverse electric field and its limitations. The 2D acceleration of electrons by a TE011 cylindrical mode is studied numerically. The trajectory, energy and phase-shift between the electron transverse velocity and the electric field are determined by the numerical solution of the relativistic Newton-Lorentz equation using a finite difference scheme. The growth rate of the magnetic field obtained is such that it maintains the phase difference within the acceleration band. The study includes the evolution of the energy for electrons initially ubicated in diferents initial points. For an electron that starts from rest and located at the radial midpoint of the transverse central plane of the cavity, it is reaches an energy close to 560 keV in 625 cycles of the microwave field using an electric field amplitude of 1 kV/cm and a frequency of 2.45 GHz.
	Poster MOPAB049 [3.541 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB049
About •	paper received ※ 17 May 2021 paper accepted ※ 14 June 2021 issue date ※ 23 August 2021
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MOPAB050	Spatial Autoresonant Acceleration of Electrons by an Axysimmetric Transverse Electric Field	217
	E.A. Orozco, O. Otero Olarte UIS, Bucaramanga, Colombia
	In this research, The autoresonance acceleration of electrons by an axisymmetric transverse electric field in presence of a stationary inhomogeneous magnetic field is studied. The dynamics of electrons is determined by the numerical solution of the relativistic Newton-Lorentz equation using a finite difference scheme. The inhomogeneous external magnetic field is generated with a three-coil system and calculated using the Biot-Savart law. The electrons move along a TE011 cylinder cavity in a stationary magnetic field whose axis coincides with the cavity axis. The magnetic field profile obtained is such that it keeps the phase difference between the electric field vector of the microwave mode and the velocity vector of the particle within the acceleration band. For an electron injected longitudinally with an energy of 1 keV and that starts at the radial midpoint of the cavity, it is accelerated up to an energy of about 185 keV using an electric field amplitude of 14 kV/cm and a frequency of 2.45 GHz at a distance of 14 cm.
	Poster MOPAB050 [3.298 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB050
About •	paper received ※ 17 May 2021 paper accepted ※ 15 June 2021 issue date ※ 30 August 2021
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MOPAB051	Operation of the ESRF Booster with the New EBS Storage Ring	221
	N. Carmignani, L.R. Carver, S.M. Liuzzo, T.P. Perron, S.M. White ESRF, Grenoble, France
	The Extremely Brilliant Source (EBS) has replaced the old ESRF Storage Ring (SR) during the 2019 one-year shutdown. The injector chain, composed of a Linac, a booster synchrotron, and two transfer lines, was not replaced. Nevertheless, some major hardware upgrades were anticipated prior to the long shutdown to ensure its long-term reliability. The shutdown interventions focused on reducing the machine circumference to cope with the new RF frequency of the SR. The status of the upgraded booster will be presented with a focus on the strategy used to lower horizontal emittance especially via emittance exchange.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB051
About •	paper received ※ 14 May 2021 paper accepted ※ 28 May 2021 issue date ※ 25 August 2021
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MOPAB052	Study of Beam Transmission Efficiency in Injection and Ramping Process of the HEPS Booster	225
	Y.M. Peng, Z. Duan, Y. Jiao, C. Meng IHEP, Beijing, People’s Republic of China
	A high-bunch-charge mode, with a bunch charge of approximately 14.4 nC at 200 mA, has been proposed for the storage ring of High Energy Photon Source (HEPS). In order to reduce the bunch charge requirement to the injector, high-energy accumulation in the HEPS booster is proposed to combine with the on-axis swap-out injection. This allows reducing the requirement of bunch charge accelerated in HEPS booster (500 MeV-6 GeV) from over 14.4 nC to about 5 nC. It is expected that the overall transmission efficiency during the low energy injection and ramping process of the booster should be higher than 80% to fulfill the requirement. In this paper, we present the simulation results of transmission efficiency and potential improvement measures.
	Poster MOPAB052 [0.362 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB052
About •	paper received ※ 13 May 2021 paper accepted ※ 26 May 2021 issue date ※ 15 August 2021
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MOPAB057	Evaluation of Pulsed Septum Leakage Fields and Compensation for the Advanced Photon Source Upgrade	245
	M. Borland, M.S. Jaski, J. Wang ANL, Lemont, 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 upgrade is considering two options for injection: vertical-plane injection with a DC Lambertson septum and horizontal-plane injection with a pulsed septum. In the latter case, pulsed leakage fields are a concern as they will cause transient beam motion and emittance dilution. In this paper, we describe results of modeling the effect of such leakage fields on the beam. We also evaluate methods of compensating for the leakage fields, including the limited time response of correction elements. Several septum drive-pulse shapes are considered and compared.
	Poster MOPAB057 [2.066 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB057
About •	paper received ※ 17 May 2021 paper accepted ※ 26 May 2021 issue date ※ 02 September 2021
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TUPAB024	Lattice Options Comparison for a DLSR Injector	1390
	H.C. Chao, I.V. Agapov, S.A. Antipov DESY, Hamburg, Germany
	DESY IV, as a part of the injector chain, must have lower emittance for PETRA IV injection. Depending on the scenarios of the injector, two lattice options for DESY IV are presented. They are designed for different purposes. The first option comes with a high momentum compaction factor with acceptable emittance. It is designed to be a full intensity booster. The other option is with low emittance dedicated to be an accumulator at high energies. The general beam dynamics properties are simulated and discussed. Their strengths and weaknesses are compared.
	Poster TUPAB024 [0.751 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB024
About •	paper received ※ 11 May 2021 paper accepted ※ 09 June 2021 issue date ※ 31 August 2021
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WEXC04	Simulations of Beam Strikes on Advanced Photon Source Upgrade Collimators using FLASH, MARS, and elegant	2562
	J.C. Dooling, M. Borland, A.M. Grannan, C.J. Graziani, R.R. Lindberg, G. Navrotski ANL, Lemont, Illinois, USA N.M. Cook RadiaSoft LLC, Boulder, Colorado, USA D.W. Lee, Y. Lee UCSC, Santa Cruz, California, USA
	Funding: Work supported by the U.S. D.O.E.,Office of Science, Office of Basic Energy Sciences, under contract number DE-AC02- 06CH11357. Modeling of high-energy-density electron beams on collimators proposed for the Advanced Photon Source Upgrade (APS-U) storage ring (SR) is carried out with codes FLASH, MARS, and elegant. Code results are compared with experimental data from two separate beam dump studies conducted in the present APS SR. Whole beam dumps of the 6-GeV, 200 mA, ultra-low emittance beam will deposit acute doses of 30 MGy within 10 to 20 microseconds, leading to hydrodynamic behavior in the collimator material. Goals for coupling the codes include accurate modeling of the hydrodynamic behavior, methods to mitigate damage, and understanding the effects of the resulting shower downstream of the collimator. Relevant experiments, though valuable, are difficult and expensive to conduct. The coupled codes will provide a method to model differing geometries, materials, and loss scenarios. Efforts thus far have been directed toward using FLASH to reproduce observed damage seen in aluminum test pieces subjected to varying beam strike currents. Stabilizing the Eulerian mesh against large energy density gradients as well as establishing release criteria from solid to fluid forms are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEXC04
About •	paper received ※ 19 May 2021 paper accepted ※ 23 July 2021 issue date ※ 30 August 2021
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WEXC06	Eddy Current Effects on the Stored Beam Generated by the Pulsed Sextupole Magnet at KEK-PF
	H. Takaki, K. Harada, Y. Kobayashi, C. Mitsuda, T. Nogami, T. Obina, R. Takai, T. Uchiyama KEK, Ibaraki, Japan Y. Lu Sokendai, Ibaraki, Japan
	The Photon Factory (KEK-PF) has been continuously developing new technologies for the top-up injection using the pulsed multipole magnets (PMM). We demonstrated beam injection with the PMM successfully at KEK-PF and operated for synchrotron user experiments with top-up injection in four years. One of the important issues to be solved in this injection is the effect of eddy currents on the stored beam generated in the PMM and its inner coating of the ceramic duct. The magnetic field of the PMM is designed so that it does not affect the stored beam, however, the eddy currents that occurred on the coating give an unwanted kick to the stored beam at the injection. In this paper, we report eddy current effects on the stored beam generated by the pulsed sextupole magnet.
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WEPAB074	A Distributed Sextupoles Lattice for the ALBA Low Emittance Upgrade	2762
	G. Benedetti, M. Carlà, U. Iriso, Z. Martí, F. Pérez ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
	The first lattice studied in 2019 for the ALBA upgrade was a 7BA lattice with two dispersion bumps, for localised chromatic correction. That lattice had limited dynamic aperture and momentum acceptance. In 2020 we started to explore a different approach to find an MBA lattice with distributed chromatic correction that meets the same emittance goal with larger dynamic aperture and momentum acceptance. The choice of the number of bendings per cell, as well as the tuning of the magnet gradients, is carried out by developing a light weight solver that performs both the emittance and chromaticity optimisation of the arcs and the matching of the linear optics in the straight sections. We present the status of the storage ring upgrade studies, the performance of the new developed lattice, together with the issues related with the injection scheme.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB074
About •	paper received ※ 19 May 2021 paper accepted ※ 16 June 2021 issue date ※ 22 August 2021
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THPAB075	Collective (In)stability Near the Coupling Resonance	3933
	R.R. Lindberg ANL, Lemont, 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. We show how to treat transverse collective instabilities when operating in the vicinity of the coupling (or tune difference) resonance. We begin by defining the approximate independent degrees of freedom including both linear coupling and chromatic effects. We then show how the destabilizing force due to wakefields and the stabilizing chromatic effects can be described by a linear combination of the horizontal and vertical motion that depends upon how close one is to the resonance. The theory agrees well with tracking studies, and will be relevant for those next-generation storage rings that plan to operate near the coupling resonance to produce nearly round beams, including the multi-bend achromat upgrade for the Advanced Photon Source.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB075
About •	paper received ※ 20 May 2021 paper accepted ※ 27 July 2021 issue date ※ 01 September 2021
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FRXA02	Advances in Beam Stability in Low-Emittance Synchrotron Light Sources
	G.M. Wang BNL, Upton, New York, USA
	The evolution and maturation of user applications at low-emittance light sources is driving new, more stringent requirements for electron beam stability in the source points. Long high-spatial-resolution, nano-focus, and high-energy-resolution beamlines demand that the beam orbit and envelope in their insertion devices are stabilized to a small degree of the beam size. At the same time, the capabilities of modern electronics have been advancing rapidly in the past decade, enabling revolutionary developments in broad-bandwidth feedback systems for every dimension of beam dynamics. In addition, synergies between modern beamline and accelerator controls have opened up a pathway to develop and test the first fully integrated feedback system that can counteract drifts and vibrations, allowing us to meet these tight stability requirements. In this presentation we will discuss the stability requirements for premier instruments at NSLS-II and summarize our recent developments in this area.
	Slides FRXA02 [2.914 MB]
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FRXA03	Harmonic Rf Cavities and Instabilities in Electron Storage Rings
	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. Higher-harmonic rf cavities (HHC) are employed in several storage-ring light sources to lengthen the bunches and increase Touschek lifetime; their use is gaining further popularity in the new-generation machines as stronger intra-beam particle scattering is the unavoidable price to pay for higher brightness. Historically, HHCs were first introduced as a way to control certain collective instabilities. While often dubbed as "Landau cavities" (with reference to the damping potentially associated with the HHC-induced synchrotron-oscillation frequency spread), their effect on beam stability is, in fact, not necessarily always beneficial. Whether the HHCs help stabilize a beam, aggravate existing instabilities, or introduce new ones, is a complicated matter that depends on various circumstances. With focus on normal-conducting passive HHCs this talk will present some recent progress and revisit some older results on instability collective-mode theory illustrating aspects of the complex impact that HHCs have on beam dynamics. We will also review some open problems, making the case for the need of further theory development beyond conventional mode analysis.
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FRXA05	Record High Extraction Efficiency of Free electron Laser Oscillator
	H. Zen, H. Ohgaki Kyoto University, Kyoto, Japan R. Hajima QST, Tokai, Japan
	Funding: This work was supported by the MEXT Quantum Leap Flagship Program (MEXT Q-LEAP) Grant Number JPMXS0118070271. The highest extraction efficiency (9.4%) of a free electron laser (FEL) oscillator has been achieved at the mid-infrared FEL facility of Kyoto University. Because of the interaction between the electron beam and FEL electromagnetic field, a maximum electron energy decrease of 16% was observed. The measured energy decrease was consistent with the measured FEL spectrum. An FEL micro-pulse energy of approximately 100 micro-J with micro-pulse duration of 150 fs was observed. This result is an important milestone for the high-extraction-efficiency FEL oscillator and will contribute to the strong-field physics of atoms and molecules. H. Zen et al., Appl. Phys. Express 13, 102007 (2020).
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FRXA06	Mitigation of Beam Instabilities in the Echo-Enabled Harmonic Generation Beamline for FLASH2020+	4514
	F. Pannek, W. Hillert, D. Samoilenko University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany S. Ackermann, E. Allaria, P. Niknejadi, G. Paraskaki, L. Schaper DESY, Hamburg, Germany M.A. Pop MAX IV Laboratory, Lund University, Lund, Sweden
	With the FLASH2020+ upgrade, one of the beamlines of the free-electron laser FLASH at DESY will be based on the Echo-Enabled Harmonic Generation (EEHG) seeding scheme and provide high-repetition-rate, coherent radiation down to 4 nm. To reach this wavelength, it is necessary to imprint intricate structures on the longitudinal phase space of the electron bunch at a very high harmonic of the seed laser wavelength, making the scheme potentially vulnerable to beam instabilities. Part of the beamline is a strong chicane, which is necessary to create the dispersion required by EEHG. Resulting effects such as Coherent Synchrotron Radiation (CSR) can be very detrimental for the bunching process and have to be taken into account already in the design of the beamline to ensure optimum FEL performance. We investigate and propose possible mitigation solutions to such instabilities in the FLASH2020+ parameter range.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-FRXA06
About •	paper received ※ 19 May 2021 paper accepted ※ 20 July 2021 issue date ※ 20 August 2021
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Paper

Title

Page

Commissioning and Restart of ESRF-EBS

1

S.M. White, N. Carmignani, L.R. Carver, J. Chavanne, L. Farvacque, L. Hardy, J. Jacob, G. Le Bec, S.M. Liuzzo, T.P. Perron, Q. Qin, P. Raimondi, J.-L. Revol, K.B. Scheidt
ESRF, Grenoble, France

The ESRF operates a 6 GeV 4th generation light source, the ESRF-EBS. This storage ring is the first to implement the Hybrid Multi-Bend Achromat lattice (HMBA). The HMBA lattice provides a reduction of the horizontal emittance of approximately a factor 30 with respect to the former Double Bend Achromat (DBA) structure, considerably improving the brilliance and transverse coherence of the ESRF accelerator complex while maintaining large horizontal acceptance and excellent lifetime performance. In this report, the characteristics of the HMBA lattice will be reviewed and the beam commissioning results and first operation experience of the new ESRF storage ring will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOXA01

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paper received ※ 11 May 2021 paper accepted ※ 31 August 2021 issue date ※ 01 September 2021

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MOXA02

Status of the APS-U Project

7

R.O. Hettel
ANL, Lemont, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Sci- ence, Office of Basic Energy Sciences, under Contract No. DE-AC02- 06CH11357.
The Advanced Photon Source Upgrade (APS-U) project at the Argonne National Laboratory will re-place the existing 7-GeV, 1.1-km circumference dou-ble bend storage ring lattice with a new 6-GeV hybrid 7BA lattice that will reduce horizontal electron emit-tance from 3 nm-rad to 42 pm-rad, including IBS ef-fects for 200-mA operation. With new optimized per-manent magnet and superconducting undulators, an increase in spectral brightness of two to three orders of magnitude in the 10-100 keV X-ray energy range will be realized. The project includes nine new high performance beamlines and fifteen enhanced beam-lines that will exploit the high brightness and coher-ence of the new facility. The project is in full swing, more than 50% complete by cost, and is on schedule for first beam sometime in mid-2024, a slip of 10 months from the original schedule due to the impact of COVID-19. Project status, challenges and outstanding issues will be discussed in this article.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOXA02

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paper received ※ 21 May 2021 paper accepted ※ 09 June 2021 issue date ※ 11 August 2021

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MOXA03

Sirius Commissioning Results and Operation Status

13

L. Liu, M.B. Alves, A.C.S. Oliveira, X.R. Resende, F.H. de Sá
LNLS, Campinas, Brazil

Sirius is a 4th generation 3 GeV synchrotron light source that has just finalized the first commissioning phase at the Brazilian Center for Research in Energy and Materials (CNPEM) campus in Campinas, Brazil. This paper describes the main Accelerator Physics issues faced during the storage ring commissioning, methods that were used to work them out and the current operation status of the machine.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOXA03

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paper received ※ 20 May 2021 paper accepted ※ 10 June 2021 issue date ※ 16 August 2021

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MOPAB020

Improvements to the SLS Booster Synchrotron Performance Towards SLS 2.0

103

J. Kallestrup, M. Aiba
PSI, Villigen PSI, Switzerland

The Swiss Light Source (SLS) storage ring will undergo a major upgrade to a multi-bend achromat lattice. The existing injector complex will be reused with few modifications. However, the SLS booster synchrotron has not been studied since the initial commissioning in years 2000-2001. We plan to apply an emittance exchange in the booster to lower the horizontal emittance, which is a critial parameter for the injection. Here, we present improvements to the SLS booster as a preparation for SLS 2.0 upgrade project. The vertical beam size is decreased by 50\% by the use of vertical orbit correctors without beam position monitors, leading also to suppression of vertical dispersion and a factor 10 reduction of the transverse coupling coefficient. The emittance exchange reflected these improvements in the horizontal emittance, achieving a factor of 9-10 reduction. Lastly, a fast head-tail instability limiting the injection rate into the storage ring is discovered and subsequently suppressed by correcting the chromaticities.

Poster MOPAB020 [0.380 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB020

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paper received ※ 19 May 2021 paper accepted ※ 01 June 2021 issue date ※ 30 August 2021

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MOPAB035

Modified Lattice of the Compact Storage Ring in the cSTART Project at Karlsruhe Institute of Technology

159

A.I. Papash, E. Bründermann, B. Härer, A.-S. Müller, R. Ruprecht, J. Schäfer, M. Schuh
KIT, Karlsruhe, Germany

A very large acceptance compact storage ring (VLA-cSR) is under design at the Institute for Beam Physics and Technology (IBPT) of the Karlsruhe Institute of Technology (KIT, Germany). The combination of a compact storage ring and a laser wakefield accelerator (LWFA) might be the basis for future compact light sources and advancing user facilities. Meanwhile, the post-LWFA beam should be adapted for storage and accumulation in a dedicated storage ring. Modified geometry and lattice of a VLA-cSR operating at 50 MeV energy range have been studied in detailed simulations. The main features of a new model are described here. The new design, based on 45° bending magnets, is suitable to store the post-LWFA beam with a wide momentum spread (1% to 2%) as well as ultra-short electron bunches in the fs range from the Ferninfrarot Linac- Und Test- Experiment (FLUTE). The DBA-FDF lattice with relaxed settings, split elements, and higher-order optics of tolerable strength allows improving the dynamic aperture to an acceptable level. This contribution discusses the lattice features in detail and different possible operation schemes of a VLA-cSR.

Poster MOPAB035 [1.405 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB035

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paper received ※ 10 May 2021 paper accepted ※ 27 May 2021 issue date ※ 24 August 2021

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MOPAB038

Robustness Studies and First Commissioning Simulations for the SOLEIL Upgrade Lattice

171

D. Amorim, A. Loulergue, L.S. Nadolski, R. Nagaoka
SOLEIL, Gif-sur-Yvette, France

Diffraction limited light sources will use very strong focusing elements to achieve their emittance goal. The beam will therefore be more sensitive to magnet field and alignment errors. Impact of errors on the lattice proposed for the SOLEIL upgrade was studied with the Accelerator Toolbox (AT) code. The performance achieved with the imperfect lattice will be presented. In particular the effect of girders misalignment was also accounted for. As the lattice uses a large number of permanent magnets for the beam bending as well as the focusing, challenges arise in terms of beam correction. The correctors and BPMs location and number will be investigated to maximize their efficiency, and corrector magnet strength required to obtain a closed orbit will be studied. The commissioning strategy, and in particular the method used to achieve the first turns and a stored beam in the machine will also be exposed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB038

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paper received ※ 19 May 2021 paper accepted ※ 31 May 2021 issue date ※ 16 August 2021

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MOPAB039

Amplitude-Dependent Shift of Betatron Tunes and Its Relation to Long-Term Circumference Variations at NSLS-II

175

L.H. Yu, G. Bassi, Y. Hidaka, B. Podobedov, V.V. Smaluk, G.M. Wang, X. Yang
BNL, Upton, New York, USA

The comparison of amplitude tune dependence measured for NSLSII lattices with models indicated the large change of amplitude tune dependence over time apparently can not be solely explained by magnets variation or beta function changes, but it seems can be explained by energy changes. On the other hand, the energy change required by fitting with the amplitude tune dependence change is too large to be explained by the RF frequency change and the change of the sum of correctors in the period of the measurements. To explain this apparent contradiction, our analysis shows the long term storage ring circumference change can explain the apparent energy change. Our data indeed shows a seasonal change of the amplitude tune dependence over long term observation. This clearly also indicated a relation to long term closed orbit drift. Hence the current work indicates a new strategy to study how to use amplitude tune dependence as a guideline to analyze long term lattice parameter shifts and closed orbit drift, and improve the orbit and machine performance stability.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB039

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paper received ※ 09 May 2021 paper accepted ※ 26 May 2021 issue date ※ 26 August 2021

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MOPAB042

Beam Dynamics Investigation for a New Project of Compton Back Scattering Photon Source at NRNU MEPhI

186

V.S. Dyubkov, I.A. Ashanin, M. Gusarova, Yu.D. Kliuchevskaia, M.V. Lalayan, S.M. Polozov, A.I. Pronikov, V.I. Rashchikov
MEPhI, Moscow, Russia

Funding: This project is supported by Russian Foundation for Basic Research, Grant no. 19-29-12036.
The activities on physical models design of a compact monochromatic radiation source in the x-ray range based on inverse Compton scattering are started at NRNU MEPhI. There are comparison of two schemes of the photon source here: one of them is considered to be based on linac with variable energy of 20-60 MeV only and the other one is considered as accelerator complex where linac is supposed to be used as injector to medium size storage ring (energy up to 60 MeV). Preliminary results of linac structures and storage ring design as well as electron dynamics simulation are discussed

Poster MOPAB042 [0.962 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB042

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paper received ※ 13 May 2021 paper accepted ※ 20 May 2021 issue date ※ 10 August 2021

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MOPAB043

Validation of APS-U Beam Dynamics Using 6-GeV APS Beam

189

L. Emery, P.S. Kallakuri, R.R. Lindberg, A. Xiao
ANL, Lemont, 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.
Several beam measurements at the Advanced Photon Sources were done with a lowered-energy beam of 6 GeV in order to verify or validate calculation codes and some predictions for the APS-U. Though the APS lattice is obviously different from that of the APS-U some aspects of the beams at 6 GeV are similar, for example, the synchrotron radiation damping rate. At 6 GeV, one can also store more current and run with a higher rf bucket allowing the characterization of larger momentum aperture lattices. We report measurements (or plans of measurements) on general instabilities thresholds, lifetime, and other subtle effects. The important topic of ion instabilities at 6 GeV is covered in a separate paper by J. Calvey at this conference.

Poster MOPAB043 [0.829 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB043

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paper received ※ 20 May 2021 paper accepted ※ 23 June 2021 issue date ※ 10 August 2021

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MOPAB044

Gas Bremsstrahlung Measurements in the Advanced Photon Source Storage Ring

193

J.C. Dooling, A.R. Brill, J.R. Calvey
ANL, Lemont, Illinois, USA

Funding: Work supported by the U.S. D.O.E.,Office of Science, Office of Basic Energy Sciences, under contract number DE-AC02- 06CH11357.
In the Advanced Photon Source Upgrade storage ring (SR), small-aperture vacuum chambers provide limited conductance for pumping. Non-evaporable getter (NEG) coatings will be used in the SR to support the vacuum. Ion pumps and cold-cathode gauges are typically located away from the vacuum chamber transporting the beam. Measuring gas bremsstrahlung (GB) photons in low-conductance chambers provides a method to determine the pressure at the beam location. We report on GB measurements made in the ID-25 beamline. A Pb:Glass calorimeter radiator generates Cherenkov radiation when high-energy photons cause pair-production within the glass. A photomultiplier tube converts the light pulses to electrical signals. Data was obtained during normal machine operations starting in January 2020. Data collection was facilitated using a 4-channel ITech Beam Loss Monitor FPGA that allows for control of thresholds and attenuation settings in both counting and pulse-height acquisition modes. Count rates and spectra were recorded for the three primary fill patterns typically used during SR operations as well as during gas injection experiments; results of these measurements will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB044

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paper received ※ 22 May 2021 paper accepted ※ 28 May 2021 issue date ※ 25 August 2021

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MOPAB045

Measurements and Simulations of High Charge Beam in the APS Booster

197

J.R. Calvey, J.C. Dooling, K.C. Harkay, K.P. Wootton, C. Yao
ANL, Lemont, Illinois, USA

For the APS-Upgrade, swap-out injection will require the booster to support up to 17 nC bunch charge, several times what is used in the present APS. Booster injection efficiency drops sharply at high charge, and is the present bottleneck limiting high charge transport through the injectors. Particle tracking simulations have been used to understand what causes are limiting the injection efficiency, and to guide plans for improving it. In particular, bunch length blowup in the injected beam and beam loading in the RF cavities have been identified as the biggest factors. Simulations and measurements have also been done to characterize beam properties along the booster energy ramp. So far, a bunch charge of 12 nC has been successfully extracted from the booster.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB045

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paper received ※ 19 May 2021 paper accepted ※ 26 July 2021 issue date ※ 16 August 2021

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MOPAB046

Plan for Operating the APS-Upgrade Booster with a Frequency Sweep

201

J.R. Calvey, T.G. Berenc, A.R. Brill, L. Emery, T. Fors, K.C. Harkay, T.J. Madden, N. Sereno, U. Wienands
ANL, Lemont, Illinois, USA
A. Gu
UCB, Berkeley, California, USA

The APS-Upgrade presents several challenging demands to the booster synchrotron. Swap-out injection requires the booster to capture a high charge bunch (up to 17 nC), accelerate it to 6 GeV, and maintain a low emittance at extraction for injection into the storage ring. To accommodate these conflicting demands, the RF frequency will be ramped between injection and extraction. However, the RF cavity tuners will remain static, which means the couplers will need to withstand a high reflected power at extraction. This paper presents a plan for a system that will meet the requirements for injection efficiency, extracted emittance, and equivalent power at the coupler. Results from tracking simulations and beam studies with a frequency ramp will also be shown.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB046

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paper received ※ 28 May 2021 paper accepted ※ 02 June 2021 issue date ※ 26 August 2021

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MOPAB047

A CAD Tool for Linear Optics Design: A Use Case Approach

205

J. Bengtsson
HZB, Berlin, Germany
T.J.R. Nicholls, W.A.H. Rogers
DLS, Oxfordshire, United Kingdom

The formula relevant for linear optics design of synchrotrons are derived systematically from first principles, i.e., an exercise in Hamiltonian dynamics. Equipped with these, the relevant use cases are then captured; for a streamlined approach. To enable professionals, i.e., software engineers, to efficiently prototype & architect a CAD tool available to mechanical engineers since the mid-1960s. In other words, robust design of a modern synchrotron is an exercise in/pursuit of the art of Engineering-Science.

Poster MOPAB047 [1.059 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB047

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paper received ※ 17 May 2021 paper accepted ※ 28 May 2021 issue date ※ 15 August 2021

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MOPAB049

Gyroresonant Acceleration of Electrons by an Axisymmetric Transverse Electric Field

213

E.A. Orozco, O. Otero Olarte
UIS, Bucaramanga, Colombia

The acceleration of electrons using gyromagnetic autoresonance consist on the sustaint of the electron cyclotron resonant condition through of a magnetic field which increase on time, this scheme was propose by K. S. Golovanivsky. In this work, we considerer the gyroresonant acceleration of electrons using an axisymmetric transverse electric field and its limitations. The 2D acceleration of electrons by a TE011 cylindrical mode is studied numerically. The trajectory, energy and phase-shift between the electron transverse velocity and the electric field are determined by the numerical solution of the relativistic Newton-Lorentz equation using a finite difference scheme. The growth rate of the magnetic field obtained is such that it maintains the phase difference within the acceleration band. The study includes the evolution of the energy for electrons initially ubicated in diferents initial points. For an electron that starts from rest and located at the radial midpoint of the transverse central plane of the cavity, it is reaches an energy close to 560 keV in 625 cycles of the microwave field using an electric field amplitude of 1 kV/cm and a frequency of 2.45 GHz.

Poster MOPAB049 [3.541 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB049

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paper received ※ 17 May 2021 paper accepted ※ 14 June 2021 issue date ※ 23 August 2021

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MOPAB050

Spatial Autoresonant Acceleration of Electrons by an Axysimmetric Transverse Electric Field

217

E.A. Orozco, O. Otero Olarte
UIS, Bucaramanga, Colombia

In this research, The autoresonance acceleration of electrons by an axisymmetric transverse electric field in presence of a stationary inhomogeneous magnetic field is studied. The dynamics of electrons is determined by the numerical solution of the relativistic Newton-Lorentz equation using a finite difference scheme. The inhomogeneous external magnetic field is generated with a three-coil system and calculated using the Biot-Savart law. The electrons move along a TE011 cylinder cavity in a stationary magnetic field whose axis coincides with the cavity axis. The magnetic field profile obtained is such that it keeps the phase difference between the electric field vector of the microwave mode and the velocity vector of the particle within the acceleration band. For an electron injected longitudinally with an energy of 1 keV and that starts at the radial midpoint of the cavity, it is accelerated up to an energy of about 185 keV using an electric field amplitude of 14 kV/cm and a frequency of 2.45 GHz at a distance of 14 cm.

Poster MOPAB050 [3.298 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB050

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paper received ※ 17 May 2021 paper accepted ※ 15 June 2021 issue date ※ 30 August 2021

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MOPAB051

Operation of the ESRF Booster with the New EBS Storage Ring

221

N. Carmignani, L.R. Carver, S.M. Liuzzo, T.P. Perron, S.M. White
ESRF, Grenoble, France

The Extremely Brilliant Source (EBS) has replaced the old ESRF Storage Ring (SR) during the 2019 one-year shutdown. The injector chain, composed of a Linac, a booster synchrotron, and two transfer lines, was not replaced. Nevertheless, some major hardware upgrades were anticipated prior to the long shutdown to ensure its long-term reliability. The shutdown interventions focused on reducing the machine circumference to cope with the new RF frequency of the SR. The status of the upgraded booster will be presented with a focus on the strategy used to lower horizontal emittance especially via emittance exchange.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB051

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paper received ※ 14 May 2021 paper accepted ※ 28 May 2021 issue date ※ 25 August 2021

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MOPAB052

Study of Beam Transmission Efficiency in Injection and Ramping Process of the HEPS Booster

225

Y.M. Peng, Z. Duan, Y. Jiao, C. Meng
IHEP, Beijing, People’s Republic of China

A high-bunch-charge mode, with a bunch charge of approximately 14.4 nC at 200 mA, has been proposed for the storage ring of High Energy Photon Source (HEPS). In order to reduce the bunch charge requirement to the injector, high-energy accumulation in the HEPS booster is proposed to combine with the on-axis swap-out injection. This allows reducing the requirement of bunch charge accelerated in HEPS booster (500 MeV-6 GeV) from over 14.4 nC to about 5 nC. It is expected that the overall transmission efficiency during the low energy injection and ramping process of the booster should be higher than 80% to fulfill the requirement. In this paper, we present the simulation results of transmission efficiency and potential improvement measures.

Poster MOPAB052 [0.362 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB052

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paper received ※ 13 May 2021 paper accepted ※ 26 May 2021 issue date ※ 15 August 2021

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MOPAB057

Evaluation of Pulsed Septum Leakage Fields and Compensation for the Advanced Photon Source Upgrade

245

M. Borland, M.S. Jaski, J. Wang
ANL, Lemont, 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 upgrade is considering two options for injection: vertical-plane injection with a DC Lambertson septum and horizontal-plane injection with a pulsed septum. In the latter case, pulsed leakage fields are a concern as they will cause transient beam motion and emittance dilution. In this paper, we describe results of modeling the effect of such leakage fields on the beam. We also evaluate methods of compensating for the leakage fields, including the limited time response of correction elements. Several septum drive-pulse shapes are considered and compared.

Poster MOPAB057 [2.066 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB057

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paper received ※ 17 May 2021 paper accepted ※ 26 May 2021 issue date ※ 02 September 2021

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TUPAB024

Lattice Options Comparison for a DLSR Injector

1390

H.C. Chao, I.V. Agapov, S.A. Antipov
DESY, Hamburg, Germany

DESY IV, as a part of the injector chain, must have lower emittance for PETRA IV injection. Depending on the scenarios of the injector, two lattice options for DESY IV are presented. They are designed for different purposes. The first option comes with a high momentum compaction factor with acceptable emittance. It is designed to be a full intensity booster. The other option is with low emittance dedicated to be an accumulator at high energies. The general beam dynamics properties are simulated and discussed. Their strengths and weaknesses are compared.

Poster TUPAB024 [0.751 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB024

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paper received ※ 11 May 2021 paper accepted ※ 09 June 2021 issue date ※ 31 August 2021

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WEXC04

Simulations of Beam Strikes on Advanced Photon Source Upgrade Collimators using FLASH, MARS, and elegant

2562

J.C. Dooling, M. Borland, A.M. Grannan, C.J. Graziani, R.R. Lindberg, G. Navrotski
ANL, Lemont, Illinois, USA
N.M. Cook
RadiaSoft LLC, Boulder, Colorado, USA
D.W. Lee, Y. Lee
UCSC, Santa Cruz, California, USA

Funding: Work supported by the U.S. D.O.E.,Office of Science, Office of Basic Energy Sciences, under contract number DE-AC02- 06CH11357.
Modeling of high-energy-density electron beams on collimators proposed for the Advanced Photon Source Upgrade (APS-U) storage ring (SR) is carried out with codes FLASH, MARS, and elegant. Code results are compared with experimental data from two separate beam dump studies conducted in the present APS SR. Whole beam dumps of the 6-GeV, 200 mA, ultra-low emittance beam will deposit acute doses of 30 MGy within 10 to 20 microseconds, leading to hydrodynamic behavior in the collimator material. Goals for coupling the codes include accurate modeling of the hydrodynamic behavior, methods to mitigate damage, and understanding the effects of the resulting shower downstream of the collimator. Relevant experiments, though valuable, are difficult and expensive to conduct. The coupled codes will provide a method to model differing geometries, materials, and loss scenarios. Efforts thus far have been directed toward using FLASH to reproduce observed damage seen in aluminum test pieces subjected to varying beam strike currents. Stabilizing the Eulerian mesh against large energy density gradients as well as establishing release criteria from solid to fluid forms are discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEXC04

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paper received ※ 19 May 2021 paper accepted ※ 23 July 2021 issue date ※ 30 August 2021

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WEXC06

Eddy Current Effects on the Stored Beam Generated by the Pulsed Sextupole Magnet at KEK-PF

H. Takaki, K. Harada, Y. Kobayashi, C. Mitsuda, T. Nogami, T. Obina, R. Takai, T. Uchiyama
KEK, Ibaraki, Japan
Y. Lu
Sokendai, Ibaraki, Japan

The Photon Factory (KEK-PF) has been continuously developing new technologies for the top-up injection using the pulsed multipole magnets (PMM). We demonstrated beam injection with the PMM successfully at KEK-PF and operated for synchrotron user experiments with top-up injection in four years. One of the important issues to be solved in this injection is the effect of eddy currents on the stored beam generated in the PMM and its inner coating of the ceramic duct. The magnetic field of the PMM is designed so that it does not affect the stored beam, however, the eddy currents that occurred on the coating give an unwanted kick to the stored beam at the injection. In this paper, we report eddy current effects on the stored beam generated by the pulsed sextupole magnet.

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WEPAB074

A Distributed Sextupoles Lattice for the ALBA Low Emittance Upgrade

2762

G. Benedetti, M. Carlà, U. Iriso, Z. Martí, F. Pérez
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain

The first lattice studied in 2019 for the ALBA upgrade was a 7BA lattice with two dispersion bumps, for localised chromatic correction. That lattice had limited dynamic aperture and momentum acceptance. In 2020 we started to explore a different approach to find an MBA lattice with distributed chromatic correction that meets the same emittance goal with larger dynamic aperture and momentum acceptance. The choice of the number of bendings per cell, as well as the tuning of the magnet gradients, is carried out by developing a light weight solver that performs both the emittance and chromaticity optimisation of the arcs and the matching of the linear optics in the straight sections. We present the status of the storage ring upgrade studies, the performance of the new developed lattice, together with the issues related with the injection scheme.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB074

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paper received ※ 19 May 2021 paper accepted ※ 16 June 2021 issue date ※ 22 August 2021

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THPAB075

Collective (In)stability Near the Coupling Resonance

3933

R.R. Lindberg
ANL, Lemont, 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.
We show how to treat transverse collective instabilities when operating in the vicinity of the coupling (or tune difference) resonance. We begin by defining the approximate independent degrees of freedom including both linear coupling and chromatic effects. We then show how the destabilizing force due to wakefields and the stabilizing chromatic effects can be described by a linear combination of the horizontal and vertical motion that depends upon how close one is to the resonance. The theory agrees well with tracking studies, and will be relevant for those next-generation storage rings that plan to operate near the coupling resonance to produce nearly round beams, including the multi-bend achromat upgrade for the Advanced Photon Source.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB075

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paper received ※ 20 May 2021 paper accepted ※ 27 July 2021 issue date ※ 01 September 2021

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FRXA02

Advances in Beam Stability in Low-Emittance Synchrotron Light Sources

G.M. Wang
BNL, Upton, New York, USA

The evolution and maturation of user applications at low-emittance light sources is driving new, more stringent requirements for electron beam stability in the source points. Long high-spatial-resolution, nano-focus, and high-energy-resolution beamlines demand that the beam orbit and envelope in their insertion devices are stabilized to a small degree of the beam size. At the same time, the capabilities of modern electronics have been advancing rapidly in the past decade, enabling revolutionary developments in broad-bandwidth feedback systems for every dimension of beam dynamics. In addition, synergies between modern beamline and accelerator controls have opened up a pathway to develop and test the first fully integrated feedback system that can counteract drifts and vibrations, allowing us to meet these tight stability requirements. In this presentation we will discuss the stability requirements for premier instruments at NSLS-II and summarize our recent developments in this area.

Slides FRXA02 [2.914 MB]

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FRXA03

Harmonic Rf Cavities and Instabilities in Electron Storage Rings

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.
Higher-harmonic rf cavities (HHC) are employed in several storage-ring light sources to lengthen the bunches and increase Touschek lifetime; their use is gaining further popularity in the new-generation machines as stronger intra-beam particle scattering is the unavoidable price to pay for higher brightness. Historically, HHCs were first introduced as a way to control certain collective instabilities. While often dubbed as "Landau cavities" (with reference to the damping potentially associated with the HHC-induced synchrotron-oscillation frequency spread), their effect on beam stability is, in fact, not necessarily always beneficial. Whether the HHCs help stabilize a beam, aggravate existing instabilities, or introduce new ones, is a complicated matter that depends on various circumstances. With focus on normal-conducting passive HHCs this talk will present some recent progress and revisit some older results on instability collective-mode theory illustrating aspects of the complex impact that HHCs have on beam dynamics. We will also review some open problems, making the case for the need of further theory development beyond conventional mode analysis.

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FRXA05

Record High Extraction Efficiency of Free electron Laser Oscillator

H. Zen, H. Ohgaki
Kyoto University, Kyoto, Japan
R. Hajima
QST, Tokai, Japan

Funding: This work was supported by the MEXT Quantum Leap Flagship Program (MEXT Q-LEAP) Grant Number JPMXS0118070271.
The highest extraction efficiency (9.4%) of a free electron laser (FEL) oscillator has been achieved at the mid-infrared FEL facility of Kyoto University*. Because of the interaction between the electron beam and FEL electromagnetic field, a maximum electron energy decrease of 16% was observed. The measured energy decrease was consistent with the measured FEL spectrum. An FEL micro-pulse energy of approximately 100 micro-J with micro-pulse duration of 150 fs was observed. This result is an important milestone for the high-extraction-efficiency FEL oscillator and will contribute to the strong-field physics of atoms and molecules.
*H. Zen et al., Appl. Phys. Express 13, 102007 (2020).

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FRXA06

Mitigation of Beam Instabilities in the Echo-Enabled Harmonic Generation Beamline for FLASH2020+

4514

F. Pannek, W. Hillert, D. Samoilenko
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
S. Ackermann, E. Allaria, P. Niknejadi, G. Paraskaki, L. Schaper
DESY, Hamburg, Germany
M.A. Pop
MAX IV Laboratory, Lund University, Lund, Sweden

With the FLASH2020+ upgrade, one of the beamlines of the free-electron laser FLASH at DESY will be based on the Echo-Enabled Harmonic Generation (EEHG) seeding scheme and provide high-repetition-rate, coherent radiation down to 4 nm. To reach this wavelength, it is necessary to imprint intricate structures on the longitudinal phase space of the electron bunch at a very high harmonic of the seed laser wavelength, making the scheme potentially vulnerable to beam instabilities. Part of the beamline is a strong chicane, which is necessary to create the dispersion required by EEHG. Resulting effects such as Coherent Synchrotron Radiation (CSR) can be very detrimental for the bunching process and have to be taken into account already in the design of the beamline to ensure optimum FEL performance. We investigate and propose possible mitigation solutions to such instabilities in the FLASH2020+ parameter range.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-FRXA06

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paper received ※ 19 May 2021 paper accepted ※ 20 July 2021 issue date ※ 20 August 2021

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