FLS2023 - Table of Session: TU4P (Poster Session)

Paper	Title	Page
TU4P05	Design of the Test Platform for High Current VHF Electron Gun	80
	Z.P. Liu, X.D. Li SINAP, Shanghai, People’s Republic of China H.X. Deng, Z.G. Jiang SARI-CAS, Pudong, Shanghai, People’s Republic of China H.J. Qian DESY Zeuthen, Zeuthen, Germany G. Shu IHEP, Beijing, People’s Republic of China
	A high-average-current VHF electron gun operating in the CW mode is under construction at Shanghai Advanced Research Institute, which is the key component of a kW-power-order free electron laser facility. The average current and the frequency of this electron gun is 1-10 mA and 217 MHz, respectively. To validate the performance of this instrument, a test platform has been designed. The R&D of its vacuum and diagnostics are presented in this work.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P05
About •	Received ※ 23 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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TU4P06	The Experimental Progress for the Strong Field Terahertz Radiation at Shanghai Soft X-ray Free-electron Laser Facility	83
	K.Q. Zhang, C. Feng SSRF, Shanghai, People’s Republic of China Y. Kang SINAP, Shanghai, People’s Republic of China
	Strong field Terahertz (THz) light source has been in-creasingly important for many scientific frontiers, while it is still a challenge to obtain THz radiation with high pulse energy at wide-tunable frequency. In this paper, we introduce an accelerator-based strong filed THz light source to obtain coherent THz radiation with high pulse energy and tunable frequency and X-ray pulse at the same time, which adopts a frequency beating laser pulse modulated electron beam. Here, we present the experi-mental progress for the strong filed THz radiation at shanghai soft X-ray free-electron laser (SXFEL) facility and show its simulated radiation performance.
	Poster TU4P06 [1.310 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P06
About •	Received ※ 21 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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TU4P07	Design of the Beam Distribution System of SHINE	87
	S. Chen SSRF, Shanghai, People’s Republic of China H.X. Deng, X. Fu, B. Liu SARI-CAS, Pudong, Shanghai, People’s Republic of China B.Y. Yan SINAP, Shanghai, People’s Republic of China
	The Shanghai high-repetition-rate XFEL and extreme light facility (SHINE), as the first hard X-ray free electron laser facility in China, is now under construction. CW electron beam with up to 1 MHz bunch repetition rate from a superconducting RF linac is used to feed at least three individual undulator lines that covers a wide photon energy range (0.4 keV ~ 25 keV). In order to maximize the efficiency of the facility, a beam switchyard between the linac and undulator lines is used to enable the simultaneously operation of the three undulator lines. In this work, the schematic design of the beam switchyard for bunch-by-bunch beam separation of CW beam is described, and the current lattice design of the linac-to-undulator deflection branches and the start-to-end tracking simulation results are presented.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P07
About •	Received ※ 22 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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TU4P08	Design and Commissioning of the Beam Switchyard for the SXFEL-UF	91
	S. Chen, K.Q. Zhang SSRF, Shanghai, People’s Republic of China H.X. Deng, C. Feng, B. Liu, T. Liu, Z. Qi, Z.T. Zhao SARI-CAS, Pudong, Shanghai, People’s Republic of China
	As an important measure of improving the efficiency and usability of X-ray free electron laser facilities, parallel operation of multiple undulator lines realized by a beam switchyard has become a standard configuration in the recent built XFEL facilities. SXFEL-UF, the first soft X-ray free electron laser user facility in China, has finished construction and commissioning recently. The electron beams from the linac are separated and delivered alternately to the two parallel undulator beam lines through a beam switchyard. A stable and fast kicker magnet is used to achieve bunch-by-bunch separation. Optics measures are applied to mitigate the impact of various collective effects, such as coherent synchrotron radiation and micro-bunching instability, on the beam quality after passing through the deflection line of the beam switchyard. In this study, the comprehensive physical design of the beam switchyard is described and the latest results of its commissioning process are presented.
	Poster TU4P08 [4.643 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P08
About •	Received ※ 23 August 2023 — Revised ※ 30 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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TU4P11	Symmetric Compton Scattering: A Way Towards Plasma Heating and Tunable Mono-chromatic Gamma-rays	95
	L. Serafini, A. Bacci, I. Drebotpresenter, M. Rossetti Conti, S. Samsam INFN-Milano, Milano, Italy C. Curatolo INFN- Sez. di Padova, Padova, Italy V. Petrillo, A. Puppin Universita’ degli Studi di Milano & INFN, Milano, Italy
	We analyze the transition between Compton Scattering and Inverse Compton Scattering (ICS), characterized by an equal exchange of energy and momentum between the colliding particles (electrons and photons). In this Symmetric Compton Scattering (SCS) regime, the energy-angle correlation of scattered photons is cancelled, and, when the electron recoil is large, monochromaticity is transferred from one colliding beam to the other. Large-recoil SCS or quasi-SCS can be used to design compact intrinsic monochromatic γ-ray sources based on compact linacs, thus avoiding the use of GeV-class electron beams and powerful laser/optical systems as required for ICS sources. At very low recoil and energy collisions (about 10 keV energy range), SCS can be exploited to heat the colliding electron beam, which is scattered with large transverse momenta over the entire solid angle, offering a technique to trap electrons into magnetic bottles for plasma heating.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P11
About •	Received ※ 24 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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TU4P12	Injection Into XFELs, a Review of Trends and Challenges	99
	C. Davut UMAN, Manchester, United Kingdom O. Apsimonpresenter Cockcroft Institute, Warrington, Cheshire, United Kingdom B.L. Militsyn, S.S. Percival STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Funding: Science and Technology Facilities Council, STFC In this contribution, we review the low-energy electron injectors for existing X-ray Free-Electron Laser (XFEL) facilities focusing on the buncher and booster sections. The technology choices are parallel to the increasing demand for stricter six-dimensional phase space quality. The current capability for beam parameters and future requirements are laid out alongside a discussion on challenges and technological bottlenecks. In light of this review, preliminary results for a high capability injector providing high repetition rate, and continuous wave emission is presented as an option for the UK XFEL.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P12
About •	Received ※ 23 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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TU4P13	An Introduction to the UK XFEL Conceptual Design and Options Analysis	103
	D.J. Dunning, D. Angal-Kalininpresenter, J.A. Clarke, J. Henderson, S.L. Mathisen, B.L. Militsyn, M.D. Roper, E.W. Snedden, N. Thompson, D.A. Walsh, P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom P. Aden, B.D. Fell STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom D. Angal-Kalininpresenter, J.A. Clarke, D.J. Dunning, J. Henderson, B.L. Militsyn, N. Thompson, P.H. Williams Cockcroft Institute, Warrington, Cheshire, United Kingdom J.L. Collier, J.S. Green STFC/RAL, Chilton, Didcot, Oxon, United Kingdom J.P. Marangos Imperial College of Science and Technology, Department of Physics, London, United Kingdom
	In October 2022, the UK XFEL project entered a new phase to explore how best to deliver the advanced XFEL capabilities identified in the project’s Science Case. This phase includes developing a conceptual design for a unique new machine to fulfil the required capabilities and more. It also examines the possibility of investment opportunities at existing XFELs to deliver the same aims, and a comparison of the various options will be made. The desired next-generation capabilities include transform-limited operation across the entire X-ray range with pulse durations ranging from 100 as to 100 fs; evenly spaced high rep. rate pulses for enhanced data acquisition rates; optimised multi-colour FEL pulse delivery and a full array of synchronised sources (XUV-THz sources, electron beams and high power/high energy lasers). The project also incorporates sustainability as a key criteria. This contribution gives an overview of progress to date and future plans.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P13
About •	Received ※ 23 August 2023 — Revised ※ 25 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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TU4P16	Transverse Optics-based Control of the Microbunching Instability	107
	A.D. Brynes, E. Allaria, G. De Ninno, S. Di Mitri, D. Garzella, C. Spezzani Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy G. De Ninno University of Nova Gorica, Nova Gorica, Slovenia G. Perosa Università degli Studi di Trieste, Trieste, Italy C.-Y. Tsai HUST, Wuhan, People’s Republic of China
	A number of recent experimental and theoretical studies have investigated novel techniques for suppressing the microbunching instability in high-brightness linac-based light sources. This instability has long been studied as one of the causes of reduced longitudinal coherence in these machines, which are commonly suppressed using a laser heater. This contribution presents recent developments concerning the use of an optics-based scheme to mitigate the microbunching instability in the FERMI free-electron laser, paving the way towards reversible beam heating techniques that could improve the performance of future machines.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P16
About •	Received ※ 23 August 2023 — Revised ※ 29 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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TU4P17	Non-destructive Vertical Halo-monitors on the ESRF Electron Beam	112
	K.B. Scheidt ESRF, Grenoble, France
	The ESRF EBS storage ring has since spring 2022 among its electron beam diagnostics two independent units of vertical Halo-monitors. The principle and the components of this unique diagnostic will be explained in details. It uses the available X-rays in a non-used Front-End, emitted from a 0.57 T standard dipole magnet in the EBS lattice. This instrument measures the so-called "far-away" Halo level, i.e. in a zone of roughly 1-3 mm away from the beam centre, which represents 200-600 times the electron’s vertical beam-size, supposedly Gaussian, of 5 um. It is measured, and expressed quantitively in picoAmp beam current, at 1 Hz rate. Both units are yielding very satisfying and well-correlated results that will be presented in details, and in relation with studies on the electron beam and the accelerator components like variation of current, filling-patterns, vertical emittance, quality of the vacuum, settings of the undulator gaps, collimators, scrapers etc. and also in direct correlation with measurements of our 128 beamloss detectors and beam lifetime.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P17
About •	Received ※ 21 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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TU4P18	Nonlinear Dynamics Measurements at the EBS Storage Ring	116
	N. Carmignani, L.R. Carver, L. Hoummi, S.M. Liuzzo, T.P. Perron, S.M. White ESRF, Grenoble, France
	The EBS is a 4th generation synchrotron light source and it has been in user operation since August 2020 at the ESRF. Several measurements to characterise the nonlinear dynamics have been performed in 2023: nonlinear chromaticity, second order dispersion and detuning with amplitude. The results of the measurements are shown and compared with simulations.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P18
About •	Received ※ 23 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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TU4P19	Evolution of Equilibrium Parameters Ramp Including Collective Effects in the Diamond-II Booster	120
	R. Husain, R.T. Fielder, I.P.S. Martin DLS, Oxfordshire, United Kingdom P. Burrows Oxford University, Physics Department, Oxford, Oxon, United Kingdom
	Efficient top-up injection into the Diamond-II storage ring will require upgrading the booster lattice for a beam emittance of <20 nm rad and a bunch length of <40 ps, including when operating with high single-bunch charge. The small vacuum chamber dimensions will drive the resistive wall instability and may adversely affect equilibrium parameters along the beam energy ramp. In addition, various diagnostic and vacuum chamber components will generate geometric impedances which may further disrupt the equilibrium parameters. Based on the detailed engineering designs, impedance models of the major components have been simulated using CST Studio and included in ELEGANT tracking simulations of the booster. In addition, the effects of synchrotron radiation emission and intra-beam scattering on the equilibrium parameters during the ramp are studied.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P19
About •	Received ※ 22 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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TU4P20	Simulated Commissioning for Diamond-II Storage Ring from On-axis to Off-axis Injection	124
	H.-C. Chao, I.P.S. Martin DLS, Oxfordshire, United Kingdom
	The Diamond-II storage ring commissioning simulations have continued based on the previous results where on-axis injected beams are captured. The next goal is to enlarge the dynamic aperture so that off-axis injection can be achieved. The procedures include beam based alignment, beta-beating correction and linear optics correction. Details of the implementations are discussed and the simulation results are presented. In the end, we are able to reach off-axis injection which allows accumulation.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P20
About •	Received ※ 22 August 2023 — Revised ※ 30 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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TU4P26	Special Operational Modes for SLS 2.0	127
	J. Kallestrup, M. Aiba PSI, Villigen PSI, Switzerland
	The SLS 2.0 storage ring will achieve low emittance and high brightness while maintaining large dynamic aperture and lifetime comparable to the present SLS. Special operational modes are investigated to further explore the potential of the lattice. In this contribution, the first considerations on such modes for the SLS 2.0 are outlined. A promising high-brightness mode, increasing brightness by up to 25% at insertion devices with minor deterioration to dynamic and momentum aperture is presented. The use of round-beams and its impact on beam dynamics and the beamlines in the SLS 2.0 portfolio is discussed.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P26
About •	Received ※ 27 July 2023 — Revised ※ 24 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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TU4P27	Progress of the HEPS Accelerator Construction and Linac Commissioning	131
	C. Meng, J.S. Cao, Z. Duan, D.Y. He, P. He, H.F. Ji, Y. Jiao, W. Kang, J. Li, J.Y. Li, W.M. Pan, Y.M. Peng, H. Qu, S.K. Tian, G. Xu, H.S. Xu, J. Zhang, J.R. Zhang IHEP, Beijing, People’s Republic of China X.H. Lu IHEP CSNS, Guangdong Province, People’s Republic of China
	The High Energy Photon Source (HEPS) is the first fourth-generation synchrotron radiation source in China that has been on the track for construction. The accelerator complex of the light source is composed of a 7BA storage ring, a booster injector, a Linac pre-injector, and three transfer lines. In order to provide high-bunch-charge beams for the storage ring, the booster was designed to be capable of both beam acceleration from low injection energy to extraction energy and charge accumulation at the extraction energy by means of accepting electron bunches from the storage ring. The Linac was built using S-band normal conducting structures, and can provide electron beam with pulse charge up to 7 nC. This paper reports the progress of the construction of the accelerators, including the installation of the storage ring, the pre-commissioning tests of the booster, and commissioning of the Linac. In particular, the beam commissioning of the Linac will be introduced in detail.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P27
About •	Received ※ 29 August 2023 — Revised ※ 29 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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TU4P28	Useful Formulas and Example Parameters Set for the Design of SSMB Storage Rings	135
	X.J. Deng, A. Chao, W.-H. Huang, Z.Z. Li, Z. Pan, C.-X. Tang TUB, Beijing, People’s Republic of China
	A promising accelerator light source mechanism called steady-state microbunching (SSMB) has been actively studied in recent years. Here we summarize some important formulas for the design of SSMB storage rings. Generally we group our formulas into two categories, i.e., a longitudinal weak focusing storage ring for a desired radiation wavelength larger than 100 nm, and a transverse-longitudinal coupling, or a generalized longitudinal strong focusing, storage ring for a desired radiation wavelength between 1 nm and 100 nm. In each category, we have presented an example parameters set for the corresponding SSMB storage ring, to generate kW-level infrared, EUV and soft X-ray radiation, respectively.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P28
About •	Received ※ 15 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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TU4P29	Why is the Coherent Radiation from Laser-induced Microbunches Narrowbanded and Collimated	139
	X.J. Deng, A. Chao TUB, Beijing, People’s Republic of China
	There are two reasons: one is the long coherence length of radiation from micobunches imprinted by the modulation laser, the second is the finite transverse electron beam size. In other words, one is due to the longitudinal form factor, and the other the transverse form factor of the electron beam. Here we study the role of these form factors in shaping the energy spectrum and spatial distribution of microbunching radiation. The investigations are of value for cases like steady-state microbunching (SSMB), coherent harmonic generation (CHG) and free-electron laser (FEL).
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P29
About •	Received ※ 14 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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TU4P30	Optical Stochastic Cooling in a General Coupled Lattice	143
	X.J. Deng TUB, Beijing, People’s Republic of China
	Here we present a formalism of optical stochastic cooling in a 3D general coupled lattice. The formalism is general, and can treat a variety of damping and diffusion mechanisms within a single framework. We expect the work to be of value for the development of future light source.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P30
About •	Received ※ 15 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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TU4P31	A Recursive Model for Laser-Electron-Radiation Interaction in Insertion Section of SSMB Storage Ring Based on Transverse-Longitudinal Coupling Scheme	147
	C.-Y. Tsai HUST, Wuhan, People’s Republic of China X.J. Deng TUB, Beijing, People’s Republic of China
	Funding: This work is supported by the Fundamental Research Funds for the Central Universities (HUST) under Project No. 2021GCRC006 and National Natural Science Foundation of China under project No. 12275094. Recently a mechanism of the steady-state microbunching (SSMB) in a storage ring has been proposed and investigated. The SSMB aims to maintain the same excellent high repetition rate, close to continuous-wave operation, as the storage ring. Moreover, replacing the conventional RF cavity with a laser modulator for longitudinal focusing, the individual electron bunches can be microbunched in a steady state. The microbunched electron bunch train, with individual bunch length comparable to or shorter than the radiation wavelength, can not only produce coherent powerful synchrotron radiations but may also be subject to FEL-like collective instabilities. Our previous analysis was based on the wake-impedance model. In this paper, we have developed a recursive model for the laser modulator in the SSMB storage ring. In particular, the transverse-longitudinal coupling scheme is assumed. Equipped with the above matrix formalism, we can construct a recursive model to account for turn-by-turn evolution, including single-particle and second moments. It is possible to obtain a simplified analytical expression to identify the stability regime or tolerance range for non-perfect cancellation. C.-Y. Tsai, PRAB 25, 064401 (2022). C.-Y. Tsai, NIMA 1042 (2022) 167454. **X.J. Deng et al., NIMA 1019 (2021) 165859.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P31
About •	Received ※ 23 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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TU4P33	An Inverse-Compton Scattering Simulation Module for RF-Track	151
	A. Latina, V. Mușat CERN, Meyrin, Switzerland
	A simulation module implementing Inverse-Compton scattering (ICS) was added to the tracking code RF-Track. The module consists of a special beamline element that simulates the interaction between the tracked beam and a laser, making RF-Track capable of simulating a complete ICS source in one go, from the electron source to the photons. The description of the laser allows the user to thoroughly quality the laser in terms of wavelength, pulse energy, pulse length, incoming direction, M2 parameter, aspect ratio, polarisation and whether the laser profile should be Gaussian or uniform. Furthermore, as the code implements fully generic expressions, the scattering between photons and different particles than electrons can be simulated. A benchmark against CAIN showed excellent agreement and that RF-Track outperforms CAIN in terms of computational speed by orders of magnitude.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P33
About •	Received ※ 22 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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TU4P34	Recent Developments of the cSTART Project	155
	M. Schwarz, A. Bernhard, E. Bründermann, D. El Khechen, B. Härer, A. Malygin, A.-S. Müller, M.J. Nasse, G. Niehues, A.I. Papash, R. Ruprecht, J. Schäfer, M. Schuh, N.J. Smale, P. Wesolowski, C. Widmann KIT, Karlsruhe, Germany
	The combination of a compact storage ring and a laser-plasma accelerator (LPA) can serve as the basis for future compact light sources. One challenge is the large momentum spread (~ 2%) of the electron beams delivered by the LPA. To overcome this challenge, a very large acceptance compact storage ring (VLA-cSR) was designed as part of the compact STorage ring for Accelerator Research and Technology (cSTART) project. The project will be realized at the Karlsruhe Institute of Technology (KIT, Germany). Initially, the Ferninfrarot Linac- Und Test-Experiment (FLUTE), a source of ultra-short bunches, will serve as an injector for the VLA-cSR to benchmark and emulate LPA-like beams. In a second stage, a laser-plasma accelerator will be used as an injector, which is being developed as part of the ATHENA project in collaboration with DESY and the Helmholtz Institute Jena (HIJ). The small facility footprint, the large-momentum spread bunches with charges from 1 pC to 1 nC and lengths from few fs to few ps pose challenges for the lattice design, RF system and beam diagnostics. This contribution summarizes the latest results on these challenges.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P34
About •	Received ※ 21 August 2023 — Revised ※ 22 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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Paper

Title

Page

Design of the Test Platform for High Current VHF Electron Gun

80

Z.P. Liu, X.D. Li
SINAP, Shanghai, People’s Republic of China
H.X. Deng, Z.G. Jiang
SARI-CAS, Pudong, Shanghai, People’s Republic of China
H.J. Qian
DESY Zeuthen, Zeuthen, Germany
G. Shu
IHEP, Beijing, People’s Republic of China

A high-average-current VHF electron gun operating in the CW mode is under construction at Shanghai Advanced Research Institute, which is the key component of a kW-power-order free electron laser facility. The average current and the frequency of this electron gun is 1-10 mA and 217 MHz, respectively. To validate the performance of this instrument, a test platform has been designed. The R&D of its vacuum and diagnostics are presented in this work.

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P05

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Received ※ 23 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

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TU4P06

The Experimental Progress for the Strong Field Terahertz Radiation at Shanghai Soft X-ray Free-electron Laser Facility

83

K.Q. Zhang, C. Feng
SSRF, Shanghai, People’s Republic of China
Y. Kang
SINAP, Shanghai, People’s Republic of China

Strong field Terahertz (THz) light source has been in-creasingly important for many scientific frontiers, while it is still a challenge to obtain THz radiation with high pulse energy at wide-tunable frequency. In this paper, we introduce an accelerator-based strong filed THz light source to obtain coherent THz radiation with high pulse energy and tunable frequency and X-ray pulse at the same time, which adopts a frequency beating laser pulse modulated electron beam. Here, we present the experi-mental progress for the strong filed THz radiation at shanghai soft X-ray free-electron laser (SXFEL) facility and show its simulated radiation performance.

Poster TU4P06 [1.310 MB]

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P06

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Received ※ 21 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

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TU4P07

Design of the Beam Distribution System of SHINE

87

S. Chen
SSRF, Shanghai, People’s Republic of China
H.X. Deng, X. Fu, B. Liu
SARI-CAS, Pudong, Shanghai, People’s Republic of China
B.Y. Yan
SINAP, Shanghai, People’s Republic of China

The Shanghai high-repetition-rate XFEL and extreme light facility (SHINE), as the first hard X-ray free electron laser facility in China, is now under construction. CW electron beam with up to 1 MHz bunch repetition rate from a superconducting RF linac is used to feed at least three individual undulator lines that covers a wide photon energy range (0.4 keV ~ 25 keV). In order to maximize the efficiency of the facility, a beam switchyard between the linac and undulator lines is used to enable the simultaneously operation of the three undulator lines. In this work, the schematic design of the beam switchyard for bunch-by-bunch beam separation of CW beam is described, and the current lattice design of the linac-to-undulator deflection branches and the start-to-end tracking simulation results are presented.

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P07

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Received ※ 22 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

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TU4P08

Design and Commissioning of the Beam Switchyard for the SXFEL-UF

91

S. Chen, K.Q. Zhang
SSRF, Shanghai, People’s Republic of China
H.X. Deng, C. Feng, B. Liu, T. Liu, Z. Qi, Z.T. Zhao
SARI-CAS, Pudong, Shanghai, People’s Republic of China

As an important measure of improving the efficiency and usability of X-ray free electron laser facilities, parallel operation of multiple undulator lines realized by a beam switchyard has become a standard configuration in the recent built XFEL facilities. SXFEL-UF, the first soft X-ray free electron laser user facility in China, has finished construction and commissioning recently. The electron beams from the linac are separated and delivered alternately to the two parallel undulator beam lines through a beam switchyard. A stable and fast kicker magnet is used to achieve bunch-by-bunch separation. Optics measures are applied to mitigate the impact of various collective effects, such as coherent synchrotron radiation and micro-bunching instability, on the beam quality after passing through the deflection line of the beam switchyard. In this study, the comprehensive physical design of the beam switchyard is described and the latest results of its commissioning process are presented.

Poster TU4P08 [4.643 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P08

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Received ※ 23 August 2023 — Revised ※ 30 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

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TU4P11

Symmetric Compton Scattering: A Way Towards Plasma Heating and Tunable Mono-chromatic Gamma-rays

95

L. Serafini, A. Bacci, I. Drebotpresenter, M. Rossetti Conti, S. Samsam
INFN-Milano, Milano, Italy
C. Curatolo
INFN- Sez. di Padova, Padova, Italy
V. Petrillo, A. Puppin
Universita’ degli Studi di Milano & INFN, Milano, Italy

We analyze the transition between Compton Scattering and Inverse Compton Scattering (ICS), characterized by an equal exchange of energy and momentum between the colliding particles (electrons and photons). In this Symmetric Compton Scattering (SCS) regime, the energy-angle correlation of scattered photons is cancelled, and, when the electron recoil is large, monochromaticity is transferred from one colliding beam to the other. Large-recoil SCS or quasi-SCS can be used to design compact intrinsic monochromatic γ-ray sources based on compact linacs, thus avoiding the use of GeV-class electron beams and powerful laser/optical systems as required for ICS sources. At very low recoil and energy collisions (about 10 keV energy range), SCS can be exploited to heat the colliding electron beam, which is scattered with large transverse momenta over the entire solid angle, offering a technique to trap electrons into magnetic bottles for plasma heating.

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P11

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Received ※ 24 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

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TU4P12

Injection Into XFELs, a Review of Trends and Challenges

99

C. Davut
UMAN, Manchester, United Kingdom
O. Apsimonpresenter
Cockcroft Institute, Warrington, Cheshire, United Kingdom
B.L. Militsyn, S.S. Percival
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Funding: Science and Technology Facilities Council, STFC
In this contribution, we review the low-energy electron injectors for existing X-ray Free-Electron Laser (XFEL) facilities focusing on the buncher and booster sections. The technology choices are parallel to the increasing demand for stricter six-dimensional phase space quality. The current capability for beam parameters and future requirements are laid out alongside a discussion on challenges and technological bottlenecks. In light of this review, preliminary results for a high capability injector providing high repetition rate, and continuous wave emission is presented as an option for the UK XFEL.

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P12

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Received ※ 23 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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TU4P13

An Introduction to the UK XFEL Conceptual Design and Options Analysis

103

D.J. Dunning, D. Angal-Kalininpresenter, J.A. Clarke, J. Henderson, S.L. Mathisen, B.L. Militsyn, M.D. Roper, E.W. Snedden, N. Thompson, D.A. Walsh, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
P. Aden, B.D. Fell
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
D. Angal-Kalininpresenter, J.A. Clarke, D.J. Dunning, J. Henderson, B.L. Militsyn, N. Thompson, P.H. Williams
Cockcroft Institute, Warrington, Cheshire, United Kingdom
J.L. Collier, J.S. Green
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
J.P. Marangos
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

In October 2022, the UK XFEL project entered a new phase to explore how best to deliver the advanced XFEL capabilities identified in the project’s Science Case. This phase includes developing a conceptual design for a unique new machine to fulfil the required capabilities and more. It also examines the possibility of investment opportunities at existing XFELs to deliver the same aims, and a comparison of the various options will be made. The desired next-generation capabilities include transform-limited operation across the entire X-ray range with pulse durations ranging from 100 as to 100 fs; evenly spaced high rep. rate pulses for enhanced data acquisition rates; optimised multi-colour FEL pulse delivery and a full array of synchronised sources (XUV-THz sources, electron beams and high power/high energy lasers). The project also incorporates sustainability as a key criteria. This contribution gives an overview of progress to date and future plans.

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P13

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Received ※ 23 August 2023 — Revised ※ 25 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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TU4P16

Transverse Optics-based Control of the Microbunching Instability

107

A.D. Brynes, E. Allaria, G. De Ninno, S. Di Mitri, D. Garzella, C. Spezzani
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
G. De Ninno
University of Nova Gorica, Nova Gorica, Slovenia
G. Perosa
Università degli Studi di Trieste, Trieste, Italy
C.-Y. Tsai
HUST, Wuhan, People’s Republic of China

A number of recent experimental and theoretical studies have investigated novel techniques for suppressing the microbunching instability in high-brightness linac-based light sources. This instability has long been studied as one of the causes of reduced longitudinal coherence in these machines, which are commonly suppressed using a laser heater. This contribution presents recent developments concerning the use of an optics-based scheme to mitigate the microbunching instability in the FERMI free-electron laser, paving the way towards reversible beam heating techniques that could improve the performance of future machines.

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P16

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Received ※ 23 August 2023 — Revised ※ 29 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

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TU4P17

Non-destructive Vertical Halo-monitors on the ESRF Electron Beam

112

K.B. Scheidt
ESRF, Grenoble, France

The ESRF EBS storage ring has since spring 2022 among its electron beam diagnostics two independent units of vertical Halo-monitors. The principle and the components of this unique diagnostic will be explained in details. It uses the available X-rays in a non-used Front-End, emitted from a 0.57 T standard dipole magnet in the EBS lattice. This instrument measures the so-called "far-away" Halo level, i.e. in a zone of roughly 1-3 mm away from the beam centre, which represents 200-600 times the electron’s vertical beam-size, supposedly Gaussian, of 5 um. It is measured, and expressed quantitively in picoAmp beam current, at 1 Hz rate. Both units are yielding very satisfying and well-correlated results that will be presented in details, and in relation with studies on the electron beam and the accelerator components like variation of current, filling-patterns, vertical emittance, quality of the vacuum, settings of the undulator gaps, collimators, scrapers etc. and also in direct correlation with measurements of our 128 beamloss detectors and beam lifetime.

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P17

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Received ※ 21 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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TU4P18

Nonlinear Dynamics Measurements at the EBS Storage Ring

116

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

The EBS is a 4th generation synchrotron light source and it has been in user operation since August 2020 at the ESRF. Several measurements to characterise the nonlinear dynamics have been performed in 2023: nonlinear chromaticity, second order dispersion and detuning with amplitude. The results of the measurements are shown and compared with simulations.

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P18

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Received ※ 23 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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TU4P19

Evolution of Equilibrium Parameters Ramp Including Collective Effects in the Diamond-II Booster

120

R. Husain, R.T. Fielder, I.P.S. Martin
DLS, Oxfordshire, United Kingdom
P. Burrows
Oxford University, Physics Department, Oxford, Oxon, United Kingdom

Efficient top-up injection into the Diamond-II storage ring will require upgrading the booster lattice for a beam emittance of <20 nm rad and a bunch length of <40 ps, including when operating with high single-bunch charge. The small vacuum chamber dimensions will drive the resistive wall instability and may adversely affect equilibrium parameters along the beam energy ramp. In addition, various diagnostic and vacuum chamber components will generate geometric impedances which may further disrupt the equilibrium parameters. Based on the detailed engineering designs, impedance models of the major components have been simulated using CST Studio and included in ELEGANT tracking simulations of the booster. In addition, the effects of synchrotron radiation emission and intra-beam scattering on the equilibrium parameters during the ramp are studied.

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P19

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Received ※ 22 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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TU4P20

Simulated Commissioning for Diamond-II Storage Ring from On-axis to Off-axis Injection

124

H.-C. Chao, I.P.S. Martin
DLS, Oxfordshire, United Kingdom

The Diamond-II storage ring commissioning simulations have continued based on the previous results where on-axis injected beams are captured. The next goal is to enlarge the dynamic aperture so that off-axis injection can be achieved. The procedures include beam based alignment, beta-beating correction and linear optics correction. Details of the implementations are discussed and the simulation results are presented. In the end, we are able to reach off-axis injection which allows accumulation.

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P20

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Received ※ 22 August 2023 — Revised ※ 30 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

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TU4P26

Special Operational Modes for SLS 2.0

127

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

The SLS 2.0 storage ring will achieve low emittance and high brightness while maintaining large dynamic aperture and lifetime comparable to the present SLS. Special operational modes are investigated to further explore the potential of the lattice. In this contribution, the first considerations on such modes for the SLS 2.0 are outlined. A promising high-brightness mode, increasing brightness by up to 25% at insertion devices with minor deterioration to dynamic and momentum aperture is presented. The use of round-beams and its impact on beam dynamics and the beamlines in the SLS 2.0 portfolio is discussed.

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P26

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Received ※ 27 July 2023 — Revised ※ 24 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

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TU4P27

Progress of the HEPS Accelerator Construction and Linac Commissioning

131

C. Meng, J.S. Cao, Z. Duan, D.Y. He, P. He, H.F. Ji, Y. Jiao, W. Kang, J. Li, J.Y. Li, W.M. Pan, Y.M. Peng, H. Qu, S.K. Tian, G. Xu, H.S. Xu, J. Zhang, J.R. Zhang
IHEP, Beijing, People’s Republic of China
X.H. Lu
IHEP CSNS, Guangdong Province, People’s Republic of China

The High Energy Photon Source (HEPS) is the first fourth-generation synchrotron radiation source in China that has been on the track for construction. The accelerator complex of the light source is composed of a 7BA storage ring, a booster injector, a Linac pre-injector, and three transfer lines. In order to provide high-bunch-charge beams for the storage ring, the booster was designed to be capable of both beam acceleration from low injection energy to extraction energy and charge accumulation at the extraction energy by means of accepting electron bunches from the storage ring. The Linac was built using S-band normal conducting structures, and can provide electron beam with pulse charge up to 7 nC. This paper reports the progress of the construction of the accelerators, including the installation of the storage ring, the pre-commissioning tests of the booster, and commissioning of the Linac. In particular, the beam commissioning of the Linac will be introduced in detail.

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P27

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Received ※ 29 August 2023 — Revised ※ 29 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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TU4P28

Useful Formulas and Example Parameters Set for the Design of SSMB Storage Rings

135

X.J. Deng, A. Chao, W.-H. Huang, Z.Z. Li, Z. Pan, C.-X. Tang
TUB, Beijing, People’s Republic of China

A promising accelerator light source mechanism called steady-state microbunching (SSMB) has been actively studied in recent years. Here we summarize some important formulas for the design of SSMB storage rings. Generally we group our formulas into two categories, i.e., a longitudinal weak focusing storage ring for a desired radiation wavelength larger than 100 nm, and a transverse-longitudinal coupling, or a generalized longitudinal strong focusing, storage ring for a desired radiation wavelength between 1 nm and 100 nm. In each category, we have presented an example parameters set for the corresponding SSMB storage ring, to generate kW-level infrared, EUV and soft X-ray radiation, respectively.

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P28

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Received ※ 15 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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TU4P29

Why is the Coherent Radiation from Laser-induced Microbunches Narrowbanded and Collimated

139

X.J. Deng, A. Chao
TUB, Beijing, People’s Republic of China

There are two reasons: one is the long coherence length of radiation from micobunches imprinted by the modulation laser, the second is the finite transverse electron beam size. In other words, one is due to the longitudinal form factor, and the other the transverse form factor of the electron beam. Here we study the role of these form factors in shaping the energy spectrum and spatial distribution of microbunching radiation. The investigations are of value for cases like steady-state microbunching (SSMB), coherent harmonic generation (CHG) and free-electron laser (FEL).

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P29

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Received ※ 14 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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TU4P30

Optical Stochastic Cooling in a General Coupled Lattice

143

X.J. Deng
TUB, Beijing, People’s Republic of China

Here we present a formalism of optical stochastic cooling in a 3D general coupled lattice. The formalism is general, and can treat a variety of damping and diffusion mechanisms within a single framework. We expect the work to be of value for the development of future light source.

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P30

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Received ※ 15 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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TU4P31

A Recursive Model for Laser-Electron-Radiation Interaction in Insertion Section of SSMB Storage Ring Based on Transverse-Longitudinal Coupling Scheme

147

C.-Y. Tsai
HUST, Wuhan, People’s Republic of China
X.J. Deng
TUB, Beijing, People’s Republic of China

Funding: This work is supported by the Fundamental Research Funds for the Central Universities (HUST) under Project No. 2021GCRC006 and National Natural Science Foundation of China under project No. 12275094.
Recently a mechanism of the steady-state microbunching (SSMB) in a storage ring has been proposed and investigated. The SSMB aims to maintain the same excellent high repetition rate, close to continuous-wave operation, as the storage ring. Moreover, replacing the conventional RF cavity with a laser modulator for longitudinal focusing, the individual electron bunches can be microbunched in a steady state. The microbunched electron bunch train, with individual bunch length comparable to or shorter than the radiation wavelength, can not only produce coherent powerful synchrotron radiations but may also be subject to FEL-like collective instabilities. Our previous analysis was based on the wake-impedance model*. In this paper, we have developed a recursive model for the laser modulator in the SSMB storage ring. In particular, the transverse-longitudinal coupling scheme is assumed**. Equipped with the above matrix formalism, we can construct a recursive model to account for turn-by-turn evolution, including single-particle and second moments. It is possible to obtain a simplified analytical expression to identify the stability regime or tolerance range for non-perfect cancellation.
*C.-Y. Tsai, PRAB 25, 064401 (2022). C.-Y. Tsai, NIMA 1042 (2022) 167454.
**X.J. Deng et al., NIMA 1019 (2021) 165859.

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P31

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Received ※ 23 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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TU4P33

An Inverse-Compton Scattering Simulation Module for RF-Track

151

A. Latina, V. Mușat
CERN, Meyrin, Switzerland

A simulation module implementing Inverse-Compton scattering (ICS) was added to the tracking code RF-Track. The module consists of a special beamline element that simulates the interaction between the tracked beam and a laser, making RF-Track capable of simulating a complete ICS source in one go, from the electron source to the photons. The description of the laser allows the user to thoroughly quality the laser in terms of wavelength, pulse energy, pulse length, incoming direction, M2 parameter, aspect ratio, polarisation and whether the laser profile should be Gaussian or uniform. Furthermore, as the code implements fully generic expressions, the scattering between photons and different particles than electrons can be simulated. A benchmark against CAIN showed excellent agreement and that RF-Track outperforms CAIN in terms of computational speed by orders of magnitude.

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P33

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Received ※ 22 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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TU4P34

Recent Developments of the cSTART Project

155

M. Schwarz, A. Bernhard, E. Bründermann, D. El Khechen, B. Härer, A. Malygin, A.-S. Müller, M.J. Nasse, G. Niehues, A.I. Papash, R. Ruprecht, J. Schäfer, M. Schuh, N.J. Smale, P. Wesolowski, C. Widmann
KIT, Karlsruhe, Germany

The combination of a compact storage ring and a laser-plasma accelerator (LPA) can serve as the basis for future compact light sources. One challenge is the large momentum spread (~ 2%) of the electron beams delivered by the LPA. To overcome this challenge, a very large acceptance compact storage ring (VLA-cSR) was designed as part of the compact STorage ring for Accelerator Research and Technology (cSTART) project. The project will be realized at the Karlsruhe Institute of Technology (KIT, Germany). Initially, the Ferninfrarot Linac- Und Test-Experiment (FLUTE), a source of ultra-short bunches, will serve as an injector for the VLA-cSR to benchmark and emulate LPA-like beams. In a second stage, a laser-plasma accelerator will be used as an injector, which is being developed as part of the ATHENA project in collaboration with DESY and the Helmholtz Institute Jena (HIJ). The small facility footprint, the large-momentum spread bunches with charges from 1 pC to 1 nC and lengths from few fs to few ps pose challenges for the lattice design, RF system and beam diagnostics. This contribution summarizes the latest results on these challenges.

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P34

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Received ※ 21 August 2023 — Revised ※ 22 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

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