FLS2023 - List of Keywords (FEL)

Paper	Title	Other Keywords	Page
MO3A2	Status and Perspectives for the Swiss Free-Electron Laser (SwissFEL)	electron, undulator, laser, operation	26
	T. Schietinger PSI, Villigen PSI, Switzerland
	We summarize the status of SwissFEL, the X-ray free-electron laser at the Paul Scherrer Institute. Apart from some key operational performance figures the presentation covers the state of the experimental stations and their capabilities, gives a few scientific highlights and an overview of the use of special modes beyond SASE at our facility. Furthermore we report on progress of our seeding upgrade program on the soft X-ray line. Lastly we mention our long-term upgrade plans for a third undulator beamline in the tender and hard X-ray regime.
	Slides MO3A2 [8.398 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO3A2
About •	Received ※ 29 August 2023 — Revised ※ 30 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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MO3A5	FLASH: Status and Upgrade	laser, electron, undulator, operation	32
	M. Vogt, S. Schreiber, J. Zemella DESY, Hamburg, Germany
	FLASH, the Soft X-Ray and Extreme-UV Free Electron Laser at DESY, is undergoing a substantial upgrade and refurbishment project, called FLASH2020+. The project will finally enable external seeded and SASE FEL operation for a wavelength range down to 4 nm with the EEHG method. This is achieved in two long shutdowns from November 2021 to August 2022 and from June 2024 to August 2025. Key ingredient of the upgrade were installation of a laser heater, replacing two early TTF-type L-band SRF accelerating modules by modern, high-gradient XFEL-type modules, redesign of the 2nd bunch compressor, and complete redesign of the FLASH1 beam line for HGHG/EEHG seeding. This talk will report on the project and the status of FLASH after the first shutdown with emphasis on beam dynamics aspects.
	Slides MO3A5 [1.108 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO3A5
About •	Received ※ 25 August 2023 — Revised ※ 26 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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TU1C4	The CXFEL Project at Arizona State University	laser, electron, photon, timing	54
	W.S. Graves ASU, Tempe, USA
	Funding: This work supported by National Science Foundation awards 2153503, 1935994, and 1632780. The CXFEL Project encompasses the Compact X-ray Light Source (CXLS) that is now commissioning in the hard x-ray energy range 4-20 keV, and the Compact X-ray Free-Electron Laser (CXFEL) designed to lase in the soft x-ray range 300 ¿ 2500 eV. CXFEL has recently completed a 3-year design phase and just received NSF funding for construction over the next 5 years. These instruments are housed in separate purpose-built laboratories and rely on inverse Compton scattering of bright electron beams on powerful lasers to produce femtosecond pulses of x-rays from very compact linacs approximately 1 m in length. Both instruments use recently developed X-band distributed-coupling, room-temperature, standing-wave linacs and photoinjectors operating at 1 kHz repetition rates and 9300 MHz RF frequency. They rely on recently developed Yb-based lasers operating at high peak and average power to produce fs pulses of 1030 nm light at 1 kHz repetition rate with pulse energy up to 400 mJ. We present the current commissioning performance and status of CXLS. We also review the design and initial construction activities of the large collaborative effort to develop the fully coherent CXFEL.
	Slides TU1C4 [7.974 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU1C4
About •	Received ※ 30 August 2023 — Revised ※ 31 August 2023 — Accepted ※ 01 September 2023 — Issued ※ 02 December 2023
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TU2A2	Single Longitudinal Mode Generation in Slippage-dominated, Tapered-undulator SASE Soft X-ray FEL	undulator, electron, simulation, photon	70
	D.C. Nguyen, M. Dunham, W. Lou, C.E. Mayes, G. Stupakov xLight, Palo Alto, USA
	SASE FELs operating in the soft X-ray region exhibit multiple temporal and spectral spikes with an overall spectral bandwidth of about 1.5 times the FEL rho parameter. While many ideas have been proposed to achieve fully coherent X-ray FELs, only monochromatic seeding, either harmonic seeding* or SASE self-seeding*, has been experimentally demonstrated to narrow the output spectra of soft X-ray FELs. In this paper, we study a different method that relies on the Slippage-dominated Tapered Undulator (STU) SASE concept to produce a single longitudinal mode in a soft X-ray FEL driven by ~10-fs, 16-pC electron bunches. We pre-sent numerical simulation results that demonstrate single-mode generation and narrow-lined spectra without seeding in a STU-SASE FEL at 6.67 nm. E. Alaria et al., Nat Photon 7 (2013) 913-918 ** D. Ratner et al., PRL 114 (2015) 050801
	Slides TU2A2 [1.125 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU2A2
About •	Received ※ 22 August 2023 — Revised ※ 23 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	radiation, laser, electron, undulator	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	undulator, kicker, linac, electron	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	emittance, linac, MMI, undulator	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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TU4P12	Injection Into XFELs, a Review of Trends and Challenges	gun, electron, emittance, linac	99
	C. Davut UMAN, Manchester, United Kingdom Ö. Apsimon 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	photon, laser, electron, free-electron-laser	103
	D.J. Dunning, D. Angal-Kalinin, 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-Kalinin, 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	bunching, optics, laser, electron	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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TU4P31	A Recursive Model for Laser-Electron-Radiation Interaction in Insertion Section of SSMB Storage Ring Based on Transverse-Longitudinal Coupling Scheme	laser, radiation, storage-ring, bunching	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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WE3A3	Multi-FELOs Driven by a Common Electron Beam	electron, undulator, radiation, laser	164
	C.-Y. Tsai HUST, Wuhan, People’s Republic of China Y. Zhang JLab, Newport News, Virginia, USA
	Generating an FEL requires a high-brightness electron beam. To produce multiple FELs, the linac beam must be shared to enable one beam driving an undulator. This leads to a reduced average current and compromised FEL performance. Recently, a concept of multiple FELs driven by one electron beam was proposed, which enables reduction of equipment and improvement of productivity. We present here a simulation study based on an extended 1D FEL oscillator model to demonstrate this concept. The system consists of two FEL oscillators arranged side-by-side and one electron beam passing through them. As such, the second, downstream oscillator is driven by bunches already been used once, while the first oscillator always receives fresh bunches from the linac. The study shows lasing could be achieved for both oscillators, their radiation intensities at saturation are comparable, thus meet needs of users. The concept also enables a potential application using a circulator ring such that an oscillator can be driven alternately by fresh linac bunches from and used bunches in the circulator ring. Extending the concept to cases of more than two FEL oscillators driven by one beam is also explored.
	Slides WE3A3 [0.540 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE3A3
About •	Received ※ 23 August 2023 — Revised ※ 23 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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WE4P12	Upgrades of High Level Applications at Shanghai Soft X-Ray FEL Facility	electron, feedback, MMI, laser	171
	H. Luo, D. Gu, T. Liu, Z. Wang SARI-CAS, Pudong, Shanghai, People’s Republic of China K.Q. Zhang SSRF, Shanghai, People’s Republic of China
	The Shanghai soft X-ray free-electron laser(SXFEL) facility has made significant progress in recent years with the rapid, upgraded iterations of the high level software, including but not limited to energy matching, orbit feedback and load, beam optimization, etc. These tools are key components in operation and experiment of free electron laser facility. Some key applications are presented in this paper.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P12
About •	Received ※ 21 August 2023 — Revised ※ 29 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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WE4P13	Physics Design and Beam Dynamics Optimization of the SHINE Accelerator	linac, electron, emittance, cryomodule	174
	D. Gu, Z. Wang, M. Zhang SARI-CAS, Pudong, Shanghai, People’s Republic of China
	Shanghai HIgh Repetition Rate X-ray Free Electron Laser and Extreme Light Facility (SHINE) is a hard X-ray FEL facility which is driven by a 1.3 km supercon-ducting Linac, aims to provide high repetition rate pulses up to 1 MHz . In this study, we present the physics design of the SHINE accelerator and considerations of beam dynamics optimizations. Start-to-end simulation results show that, a high brightness electron beam with over 1500 A quasi-flat-top current can be attained which fully meet the requirements of FEL lines. Furthermore, design of the bypass line is also discussed.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P13
About •	Received ※ 23 August 2023 — Revised ※ 30 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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WE4P14	Layout of the Undulator-to-dump line at the SHINE	electron, undulator, radiation, linac	177
	T. Liu, S. Chen, H.X. Deng, B. Liu, Z. Qi SARI-CAS, Pudong, Shanghai, People’s Republic of China Z.F. Gao SSRF, Shanghai, People’s Republic of China N. Huang Zhangjiang Lab, Shanghai, People’s Republic of China
	The Shanghai HIgh repetitioN rate XFEL and Extreme light Facility as the first hard X-ray free-electron laser (FEL) facility in China, is currently under construction in the Zhangjiang area, Shanghai. It aims to deliver X-ray covering photon energy range from 0.4 to 25 keV, with electron beam power up to 800 kW. Downstream of the undulator line, the beam transport design of the undulator-to-dump line is critical which is mainly used for realization of FEL diagnostics based on transverse deflecting structure and beam absorption in the dump. In this manuscript we describe the current layout of this system.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P14
About •	Received ※ 20 August 2023 — Revised ※ 22 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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WE4P15	Multichromatic Free-electron Laser Generation Through Frequency-beating in a Chirped Electron Beam	electron, laser, bunching, radiation	181
	Z. Qi, C. Feng SARI-CAS, Pudong, Shanghai, People’s Republic of China
	We propose a simple method to generate mode-locked multichromatic free-electron laser (FEL) through a longitudinal phase space frequency-beating in a chirped electron beam. Utilizing the two stage modulator-chicane setups in Shanghai Soft X-ray FEL facility, together with a chirped electron beam, we are going to imprint a frequency-beating effect into the electron beam. Hence periodic bunching trains can be formed and can be used to generate mode-locked FEL radiation pulses. Theoretical analysis and numerical simulations are given out to demonstrate the performance of the method. The results indicate that mode-locked FEL in temporal and frequency domain can be formed at the 18th harmonic of the seed laser, with the central wavelength being about 14.58nm and the peak power over 2GW.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P15
About •	Received ※ 01 September 2023 — Revised ※ 01 September 2023 — Accepted ※ 01 September 2023 — Issued ※ 02 December 2023
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WE4P39	Larmor Radius Effect on IFEL Accelerator With Staggered Undulator	undulator, electron, laser, radiation	221
	R. Khullar, S.M. Khan, G. Mishra Devi Ahilya University, Indore, India
	In this paper, the theory of inverse free electron (IFEL) accelerator using staggered undulator has been discussed. The important contribution of staggered undulator parameter and the finite larmour radius effect on energy saturation, saturation length and accelerating gradient of the IFEL accelerator are included in the analysis. Considering the synchrotron radiation losses, the IFEL accelerator equations are derived. Key words- undulator, inverse free electron laser accelerator, accelerator
	Poster WE4P39 [0.786 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P39
About •	Received ※ 23 August 2023 — Revised ※ 30 August 2023 — Accepted ※ 01 September 2023 — Issued ※ 02 December 2023
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TH2C1	The COXINEL Seeded Free Electron Laser Driven by the Laser Plasma Accelerator at HZDR	laser, electron, plasma, undulator	232
	M.-E. Couprie, T. André, A. Berlioux, P. Berteaud, F. Blache, F. Bouvet, F. Briquez, Y. Dietrich, J.P. Duval, M. El Ajjouri, C. Herbeaux, N. Hubert, C.A. Kitégi, M. Labat, S. Lê, B. Leluan, A. Loulergue, F. Marteau, M.-H. Nguyen, D. Oumbarek Espinos, D. Pereira, J.P. Ricaud, P. Rommeluère, M. Sebdaoui, K. Tavakoli, M. Valléau, M.V. Vandenberghe, J. Vétéran, C. de Oliveira SOLEIL, Gif-sur-Yvette, France I.A. Andriyash, J. Gautier, J.-P. Goddet, O.S. Kononenko, G. Lambert, J.P. Rousseau, A. Tafzi, C. Thaury LOA, Palaiseau, France S. Bock, Y.Y. Chang, A.D. Debus, C. Eisenmann, R. Gebhardt, A. Ghaith, S. Grams, U. Helbig, A. Irman, M. Kuntzsch, R.G. Pausch, T. Püschel, S. Schöbel, U. Schramm, K. Steiniger, P. Ufer HZDR, Dresden, Germany M. LaBerge The University of Texas at Austin, Austin, Texas, USA V. Malka Weizmann Institute of Science, Physics, Rehovot, Israel E. Roussel PhLAM/CERLA, Villeneuve d’Ascq, France
	Laser Plasma Accelerators know a tremendous development these recent years. Being able to reach up to ~100 GV/m, they open new perspectives for compact accelerators. Their performance can be qualified by a Free Electron Laser Application. We report here on the COXINEL seeded Free Electron Laser in the UV using the using high-quality electron beam generated by the 150 TW DRACO laser. The COXINEL line developed at Synchrotron SOLEIL (France) is first introduced. First electron beam transport and undulator radiation observation using electrons from the Laser Plasma Accelerator developed at Laboratoire d’Optique Appliquée (France) are described. Then, we present the first COXINEL results driven by the DRACO laser high performance plasma accelerator after its move to Helmholtz-Zentrum Dresden-Rossendorf (HZDR) (Germany): proper electron beam transport, undulator seed and undulator radiation temporal, spectral and spatial overlaps, allowing the seeded Free Electron Laser to be observed in the UV. Good agreement is found between measurements and simulations.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TH2C1
About •	Received ※ 22 August 2023 — Revised ※ 29 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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TH3D2	Radiation Protection Issues in Undulator Upgrades for the European XFEL	undulator, radiation, photon, simulation	245
	A.T. Potter, A. Wolski The University of Liverpool, Liverpool, United Kingdom S. Casalbuoni, S. Karabekyan, H. Sinn, F. Wolff-Fabris EuXFEL, Schenefeld, Germany W. Decking, A. Leuschner, S. Liu DESY, Hamburg, Germany F. Jackson STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	European XFEL is the first free electron laser operating at MHz repetition rate with electron beam energy up to 17.5 GeV. The high repetition rate together with the high electron beam energy provides unique opportunities for users in different domains. To further extend the operation schemes, some upgrades have already been implemented and several more are planned. The advanced operation schemes may require devices inserted into the beam like slotted foil or narrow vacuum chambers such as for the corrugated structure, the Apple-X undulator, and the superconducting undulator. Due to the high beam power generated by the superconducting linac, there are concerns about increased radiation loads. Therefore, simulations and measurements have been carried out to study the radiation dose rates that may be generated. We give an overview of the simulations and measurements for the above mentioned schemes.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TH3D2
About •	Received ※ 30 August 2023 — Revised ※ 31 August 2023 — Accepted ※ 01 September 2023 — Issued ※ 02 December 2023
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TH4A4	A Proposal for Generating Fully Coherent X-ray FEL with Femtosecond Pulse Based on Fresh-Slice	polarization, radiation, undulator, electron	261
	Z.F. Gao SSRF, Shanghai, People’s Republic of China J.W. Yan EuXFEL, Schenefeld, Germany
	This study aims to propose a new principle for generating fully coherent femtosecond X-ray pulse on the Shanghai soft X-ray Free Electron Laser User Facility (SXFEL-UF), which was based on fresh-slice technique. The electron beam was kicked transversely to get a time-related transverse tilt. The sub-10-femtosecond bunch was achieved first because of the spatiotemporal synchronization effect of the seed laser modulation. Then the FEL pulse duration was even shorter because of harmonic lasing. In the cascaded HGHG mode, the laser generated by the beam tail modulated the beam head in the second stage to reach higher harmonics, while in the EEHG mode, the same part of the electron beam was modulated twice. The influence of emittance and energy chirp of the electron beam on the scheme was analyzed, and the instability caused by transverse position jitter and energy jitter of the chirped beam was evaluated. The relationship between the pulse duration and the transverse deflection of the beam is verified. The scheme is also explored to generate linearly polarized femtosecond pulse at 6 nm and circularly polarized femtosecond pulse at 3 nm simultaneously.
	Slides TH4A4 [3.281 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TH4A4
About •	Received ※ 21 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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Paper

Title

Other Keywords

Page

MO3A2

Status and Perspectives for the Swiss Free-Electron Laser (SwissFEL)

electron, undulator, laser, operation

26

T. Schietinger
PSI, Villigen PSI, Switzerland

We summarize the status of SwissFEL, the X-ray free-electron laser at the Paul Scherrer Institute. Apart from some key operational performance figures the presentation covers the state of the experimental stations and their capabilities, gives a few scientific highlights and an overview of the use of special modes beyond SASE at our facility. Furthermore we report on progress of our seeding upgrade program on the soft X-ray line. Lastly we mention our long-term upgrade plans for a third undulator beamline in the tender and hard X-ray regime.

Slides MO3A2 [8.398 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO3A2

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

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MO3A5

FLASH: Status and Upgrade

laser, electron, undulator, operation

32

M. Vogt, S. Schreiber, J. Zemella
DESY, Hamburg, Germany

FLASH, the Soft X-Ray and Extreme-UV Free Electron Laser at DESY, is undergoing a substantial upgrade and refurbishment project, called FLASH2020+. The project will finally enable external seeded and SASE FEL operation for a wavelength range down to 4 nm with the EEHG method. This is achieved in two long shutdowns from November 2021 to August 2022 and from June 2024 to August 2025. Key ingredient of the upgrade were installation of a laser heater, replacing two early TTF-type L-band SRF accelerating modules by modern, high-gradient XFEL-type modules, redesign of the 2nd bunch compressor, and complete redesign of the FLASH1 beam line for HGHG/EEHG seeding. This talk will report on the project and the status of FLASH after the first shutdown with emphasis on beam dynamics aspects.

Slides MO3A5 [1.108 MB]

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO3A5

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Received ※ 25 August 2023 — Revised ※ 26 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

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TU1C4

The CXFEL Project at Arizona State University

laser, electron, photon, timing

54

W.S. Graves
ASU, Tempe, USA

Funding: This work supported by National Science Foundation awards 2153503, 1935994, and 1632780.
The CXFEL Project encompasses the Compact X-ray Light Source (CXLS) that is now commissioning in the hard x-ray energy range 4-20 keV, and the Compact X-ray Free-Electron Laser (CXFEL) designed to lase in the soft x-ray range 300 ¿ 2500 eV. CXFEL has recently completed a 3-year design phase and just received NSF funding for construction over the next 5 years. These instruments are housed in separate purpose-built laboratories and rely on inverse Compton scattering of bright electron beams on powerful lasers to produce femtosecond pulses of x-rays from very compact linacs approximately 1 m in length. Both instruments use recently developed X-band distributed-coupling, room-temperature, standing-wave linacs and photoinjectors operating at 1 kHz repetition rates and 9300 MHz RF frequency. They rely on recently developed Yb-based lasers operating at high peak and average power to produce fs pulses of 1030 nm light at 1 kHz repetition rate with pulse energy up to 400 mJ. We present the current commissioning performance and status of CXLS. We also review the design and initial construction activities of the large collaborative effort to develop the fully coherent CXFEL.

Slides TU1C4 [7.974 MB]

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU1C4

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Received ※ 30 August 2023 — Revised ※ 31 August 2023 — Accepted ※ 01 September 2023 — Issued ※ 02 December 2023

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TU2A2

Single Longitudinal Mode Generation in Slippage-dominated, Tapered-undulator SASE Soft X-ray FEL

undulator, electron, simulation, photon

70

D.C. Nguyen, M. Dunham, W. Lou, C.E. Mayes, G. Stupakov
xLight, Palo Alto, USA

SASE FELs operating in the soft X-ray region exhibit multiple temporal and spectral spikes with an overall spectral bandwidth of about 1.5 times the FEL rho parameter. While many ideas have been proposed to achieve fully coherent X-ray FELs, only monochromatic seeding, either harmonic seeding* or SASE self-seeding**, has been experimentally demonstrated to narrow the output spectra of soft X-ray FELs. In this paper, we study a different method that relies on the Slippage-dominated Tapered Undulator (STU) SASE concept to produce a single longitudinal mode in a soft X-ray FEL driven by ~10-fs, 16-pC electron bunches. We pre-sent numerical simulation results that demonstrate single-mode generation and narrow-lined spectra without seeding in a STU-SASE FEL at 6.67 nm.
* E. Alaria et al., Nat Photon 7 (2013) 913-918
** D. Ratner et al., PRL 114 (2015) 050801

Slides TU2A2 [1.125 MB]

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU2A2

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Received ※ 22 August 2023 — Revised ※ 23 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

radiation, laser, electron, undulator

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

undulator, kicker, linac, electron

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

emittance, linac, MMI, undulator

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]

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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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TU4P12

Injection Into XFELs, a Review of Trends and Challenges

gun, electron, emittance, linac

99

C. Davut
UMAN, Manchester, United Kingdom
Ö. Apsimon
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.

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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

photon, laser, electron, free-electron-laser

103

D.J. Dunning, D. Angal-Kalinin, 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-Kalinin, 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.

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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

bunching, optics, laser, electron

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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TU4P31

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

laser, radiation, storage-ring, bunching

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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WE3A3

Multi-FELOs Driven by a Common Electron Beam

electron, undulator, radiation, laser

164

C.-Y. Tsai
HUST, Wuhan, People’s Republic of China
Y. Zhang
JLab, Newport News, Virginia, USA

Generating an FEL requires a high-brightness electron beam. To produce multiple FELs, the linac beam must be shared to enable one beam driving an undulator. This leads to a reduced average current and compromised FEL performance. Recently, a concept of multiple FELs driven by one electron beam was proposed, which enables reduction of equipment and improvement of productivity. We present here a simulation study based on an extended 1D FEL oscillator model to demonstrate this concept. The system consists of two FEL oscillators arranged side-by-side and one electron beam passing through them. As such, the second, downstream oscillator is driven by bunches already been used once, while the first oscillator always receives fresh bunches from the linac. The study shows lasing could be achieved for both oscillators, their radiation intensities at saturation are comparable, thus meet needs of users. The concept also enables a potential application using a circulator ring such that an oscillator can be driven alternately by fresh linac bunches from and used bunches in the circulator ring. Extending the concept to cases of more than two FEL oscillators driven by one beam is also explored.

Slides WE3A3 [0.540 MB]

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE3A3

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

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WE4P12

Upgrades of High Level Applications at Shanghai Soft X-Ray FEL Facility

electron, feedback, MMI, laser

171

H. Luo, D. Gu, T. Liu, Z. Wang
SARI-CAS, Pudong, Shanghai, People’s Republic of China
K.Q. Zhang
SSRF, Shanghai, People’s Republic of China

The Shanghai soft X-ray free-electron laser(SXFEL) facility has made significant progress in recent years with the rapid, upgraded iterations of the high level software, including but not limited to energy matching, orbit feedback and load, beam optimization, etc. These tools are key components in operation and experiment of free electron laser facility. Some key applications are presented in this paper.

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P12

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Received ※ 21 August 2023 — Revised ※ 29 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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WE4P13

Physics Design and Beam Dynamics Optimization of the SHINE Accelerator

linac, electron, emittance, cryomodule

174

D. Gu, Z. Wang, M. Zhang
SARI-CAS, Pudong, Shanghai, People’s Republic of China

Shanghai HIgh Repetition Rate X-ray Free Electron Laser and Extreme Light Facility (SHINE) is a hard X-ray FEL facility which is driven by a 1.3 km supercon-ducting Linac, aims to provide high repetition rate pulses up to 1 MHz . In this study, we present the physics design of the SHINE accelerator and considerations of beam dynamics optimizations. Start-to-end simulation results show that, a high brightness electron beam with over 1500 A quasi-flat-top current can be attained which fully meet the requirements of FEL lines. Furthermore, design of the bypass line is also discussed.

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P13

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

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WE4P14

Layout of the Undulator-to-dump line at the SHINE

electron, undulator, radiation, linac

177

T. Liu, S. Chen, H.X. Deng, B. Liu, Z. Qi
SARI-CAS, Pudong, Shanghai, People’s Republic of China
Z.F. Gao
SSRF, Shanghai, People’s Republic of China
N. Huang
Zhangjiang Lab, Shanghai, People’s Republic of China

The Shanghai HIgh repetitioN rate XFEL and Extreme light Facility as the first hard X-ray free-electron laser (FEL) facility in China, is currently under construction in the Zhangjiang area, Shanghai. It aims to deliver X-ray covering photon energy range from 0.4 to 25 keV, with electron beam power up to 800 kW. Downstream of the undulator line, the beam transport design of the undulator-to-dump line is critical which is mainly used for realization of FEL diagnostics based on transverse deflecting structure and beam absorption in the dump. In this manuscript we describe the current layout of this system.

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P14

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Received ※ 20 August 2023 — Revised ※ 22 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

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WE4P15

Multichromatic Free-electron Laser Generation Through Frequency-beating in a Chirped Electron Beam

electron, laser, bunching, radiation

181

Z. Qi, C. Feng
SARI-CAS, Pudong, Shanghai, People’s Republic of China

We propose a simple method to generate mode-locked multichromatic free-electron laser (FEL) through a longitudinal phase space frequency-beating in a chirped electron beam. Utilizing the two stage modulator-chicane setups in Shanghai Soft X-ray FEL facility, together with a chirped electron beam, we are going to imprint a frequency-beating effect into the electron beam. Hence periodic bunching trains can be formed and can be used to generate mode-locked FEL radiation pulses. Theoretical analysis and numerical simulations are given out to demonstrate the performance of the method. The results indicate that mode-locked FEL in temporal and frequency domain can be formed at the 18th harmonic of the seed laser, with the central wavelength being about 14.58nm and the peak power over 2GW.

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P15

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Received ※ 01 September 2023 — Revised ※ 01 September 2023 — Accepted ※ 01 September 2023 — Issued ※ 02 December 2023

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WE4P39

Larmor Radius Effect on IFEL Accelerator With Staggered Undulator

undulator, electron, laser, radiation

221

R. Khullar, S.M. Khan, G. Mishra
Devi Ahilya University, Indore, India

In this paper, the theory of inverse free electron (IFEL) accelerator using staggered undulator has been discussed. The important contribution of staggered undulator parameter and the finite larmour radius effect on energy saturation, saturation length and accelerating gradient of the IFEL accelerator are included in the analysis. Considering the synchrotron radiation losses, the IFEL accelerator equations are derived.
Key words- undulator, inverse free electron laser accelerator, accelerator

Poster WE4P39 [0.786 MB]

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P39

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Received ※ 23 August 2023 — Revised ※ 30 August 2023 — Accepted ※ 01 September 2023 — Issued ※ 02 December 2023

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TH2C1

The COXINEL Seeded Free Electron Laser Driven by the Laser Plasma Accelerator at HZDR

laser, electron, plasma, undulator

232

M.-E. Couprie, T. André, A. Berlioux, P. Berteaud, F. Blache, F. Bouvet, F. Briquez, Y. Dietrich, J.P. Duval, M. El Ajjouri, C. Herbeaux, N. Hubert, C.A. Kitégi, M. Labat, S. Lê, B. Leluan, A. Loulergue, F. Marteau, M.-H. Nguyen, D. Oumbarek Espinos, D. Pereira, J.P. Ricaud, P. Rommeluère, M. Sebdaoui, K. Tavakoli, M. Valléau, M.V. Vandenberghe, J. Vétéran, C. de Oliveira
SOLEIL, Gif-sur-Yvette, France
I.A. Andriyash, J. Gautier, J.-P. Goddet, O.S. Kononenko, G. Lambert, J.P. Rousseau, A. Tafzi, C. Thaury
LOA, Palaiseau, France
S. Bock, Y.Y. Chang, A.D. Debus, C. Eisenmann, R. Gebhardt, A. Ghaith, S. Grams, U. Helbig, A. Irman, M. Kuntzsch, R.G. Pausch, T. Püschel, S. Schöbel, U. Schramm, K. Steiniger, P. Ufer
HZDR, Dresden, Germany
M. LaBerge
The University of Texas at Austin, Austin, Texas, USA
V. Malka
Weizmann Institute of Science, Physics, Rehovot, Israel
E. Roussel
PhLAM/CERLA, Villeneuve d’Ascq, France

Laser Plasma Accelerators know a tremendous development these recent years. Being able to reach up to ~100 GV/m, they open new perspectives for compact accelerators. Their performance can be qualified by a Free Electron Laser Application. We report here on the COXINEL seeded Free Electron Laser in the UV using the using high-quality electron beam generated by the 150 TW DRACO laser. The COXINEL line developed at Synchrotron SOLEIL (France) is first introduced. First electron beam transport and undulator radiation observation using electrons from the Laser Plasma Accelerator developed at Laboratoire d’Optique Appliquée (France) are described. Then, we present the first COXINEL results driven by the DRACO laser high performance plasma accelerator after its move to Helmholtz-Zentrum Dresden-Rossendorf (HZDR) (Germany): proper electron beam transport, undulator seed and undulator radiation temporal, spectral and spatial overlaps, allowing the seeded Free Electron Laser to be observed in the UV. Good agreement is found between measurements and simulations.

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TH2C1

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Received ※ 22 August 2023 — Revised ※ 29 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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TH3D2

Radiation Protection Issues in Undulator Upgrades for the European XFEL

undulator, radiation, photon, simulation

245

A.T. Potter, A. Wolski
The University of Liverpool, Liverpool, United Kingdom
S. Casalbuoni, S. Karabekyan, H. Sinn, F. Wolff-Fabris
EuXFEL, Schenefeld, Germany
W. Decking, A. Leuschner, S. Liu
DESY, Hamburg, Germany
F. Jackson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

European XFEL is the first free electron laser operating at MHz repetition rate with electron beam energy up to 17.5 GeV. The high repetition rate together with the high electron beam energy provides unique opportunities for users in different domains. To further extend the operation schemes, some upgrades have already been implemented and several more are planned. The advanced operation schemes may require devices inserted into the beam like slotted foil or narrow vacuum chambers such as for the corrugated structure, the Apple-X undulator, and the superconducting undulator. Due to the high beam power generated by the superconducting linac, there are concerns about increased radiation loads. Therefore, simulations and measurements have been carried out to study the radiation dose rates that may be generated. We give an overview of the simulations and measurements for the above mentioned schemes.

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TH3D2

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Received ※ 30 August 2023 — Revised ※ 31 August 2023 — Accepted ※ 01 September 2023 — Issued ※ 02 December 2023

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TH4A4

A Proposal for Generating Fully Coherent X-ray FEL with Femtosecond Pulse Based on Fresh-Slice

polarization, radiation, undulator, electron

261

Z.F. Gao
SSRF, Shanghai, People’s Republic of China
J.W. Yan
EuXFEL, Schenefeld, Germany

This study aims to propose a new principle for generating fully coherent femtosecond X-ray pulse on the Shanghai soft X-ray Free Electron Laser User Facility (SXFEL-UF), which was based on fresh-slice technique. The electron beam was kicked transversely to get a time-related transverse tilt. The sub-10-femtosecond bunch was achieved first because of the spatiotemporal synchronization effect of the seed laser modulation. Then the FEL pulse duration was even shorter because of harmonic lasing. In the cascaded HGHG mode, the laser generated by the beam tail modulated the beam head in the second stage to reach higher harmonics, while in the EEHG mode, the same part of the electron beam was modulated twice. The influence of emittance and energy chirp of the electron beam on the scheme was analyzed, and the instability caused by transverse position jitter and energy jitter of the chirped beam was evaluated. The relationship between the pulse duration and the transverse deflection of the beam is verified. The scheme is also explored to generate linearly polarized femtosecond pulse at 6 nm and circularly polarized femtosecond pulse at 3 nm simultaneously.

Slides TH4A4 [3.281 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-TH4A4

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Received ※ 21 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

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