FLS2023 - List of Keywords (laser)

Paper	Title	Other Keywords	Page
MO2L2	Storage Ring Based Steady State Microbunching	radiation, storage-ring, electron, bunching	1
	A. Chao TUB, Beijing, People’s Republic of China
	Powerful light sources are highly desired tools for scientific research and for industrial applications. Electrons are the objects that most readily and easily radiate photons. A natural conclusion follows that one should pursue electron accelerators as the choice tools towards powerful light sources. How to manipulate the electron beam in the accelerator so that it radiates light most efficiently, however, remains to be studied and its physical principle and technical limits be explored and optimized for the purpose. One such proposed concepts is based on the steady state microbunching (SSMB) mechanism in an electron storage ring. We make a brief introduction of the SSMB mechanism and its recent status in this presentation.
	Slides MO2L2 [1.156 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO2L2
About •	Received ※ 25 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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MO3B4	Generating High Repetition Rate X-ray Attosecond Pulses in SAPS	radiation, storage-ring, electron, dipole	22
	W. Liu, X. Liu, Y. Zhao IHEP CSNS, Guangdong Province, People’s Republic of China Y. Jiao, X. Li, S. Wang IHEP, Beijing, People’s Republic of China
	Attosecond, which refers to 10^-18 seconds, is the timescale of electron motion within an atom. Accurate observation of electron motion helps deepen the understanding of microscopic quantum processes such as charge transfer in molecules, wave packet dynamics, and charge transfer in organic photovoltaic materials. To meet the needs of relevant research, the South Advanced Photon Source (SAPS), currently in the design phase, is considering the construction of an attosecond beamline. This paper presents relevant research on achieving high-repetition-rate coherent attosecond pulses on the fourth-generation storage ring at SAPS. Realizing attosecond pulses in a storage ring requires femtosecond to sub-femtosecond-level longitudinal modulation of the beam, and the modulation scheme needs to consider multiple factors to avoid a significant impact on other users. The study shows that with high-power, few-cycle lasers, and advanced beam modulation techniques, the photon flux of attosecond pulses can be significantly enhanced with a minimal impact on the brightness of synchrotron radiation. Adopting high-repetition-rate lasers and precise time delay control, the repetition rate of attosecond pulses at SAPS can reach the megahertz level. Currently, the design wavelength range for attosecond pulses covers the water window (2.3-4.4 nm), which is "transparent" to water but strongly absorbed by elements constituting living organisms. This wavelength range has significant application value in fields such as biology and chemistry.
	Slides MO3B4 [3.400 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO3B4
About •	Received ※ 23 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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MO3A2	Status and Perspectives for the Swiss Free-Electron Laser (SwissFEL)	FEL, electron, undulator, 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	FEL, 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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TU1C1	An Efficient Optimisation of a Burst Mode-Operated Fabry-Perot Cavity for Compton Light Sources	cavity, electron, photon, optics	46
	V. Mușat, E. Granados, A. Latina CERN, Meyrin, Switzerland E. Cormier CELIA, Talence, France G. Santarelli ILE, Palaiseau Cedex, France
	The burst mode operation of a Fabry-Perot cavity (FPC) allows for the generation of a high-intensity photon beam in inverse Compton scattering (ICS) sources. The geometry and burst mode parameters of the FPC can be optimised to maximise the scattered photon flux. A novel optimisation method is presented, significantly improving processing speed and accuracy. The FPC’s dimensions, mirror requirements, and effective energy can be obtained from the electron beam parameters at the interaction point. A multi-objective optimization algorithm was used to derive the geometrical parameters of the FPC; this brought orders of magnitude increase in computation speed if compared to the nominal Monte Carlo-based approaches. The burst mode parameters of the FPC were obtained by maximizing the effective energy of the laser pulse in the FPC. The impact of optical losses and thermal lensing on the FPC parameters is addressed. Preliminary parameters of an ICS source implementing this novel optimisation are presented. The source could reach high-performance photon beams for high-energy applications.
	Slides TU1C1 [1.776 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU1C1
About •	Received ※ 22 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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TU1C2	Evolution of the Inverse Compton Scattering X-ray Source of the ELSA Accelerator	electron, alignment, scattering, cavity	50
	A. Pires, R. Rosch, J. Touguet CEA, Arpajon, France N. Delerue Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France V. Le Flanchec CEA/DAM/DIF, Arpajon, France
	The Inverse Compton Scattering (ICS) X-ray source of ELSA accelerator at CEA-DAM, presents an efficient approach for generating X-rays with a compact linac. The source consists of a 30 MeV, 15 ps rms, up to 3 nC electron beam; and a table-top Nd:YAG laser. X-rays are produced in the 10-80 keV range, higher X-ray energies achieved with frequency doubling of the laser. The yield is increased by a factor of 8 thanks to an optical mirror system developed at CEA, folding the laser beam path and accumulating successive laser pulses. We present a new version of the device, with improvement of mechanical constraints management, adjunction of motorized mirrors, and a new imaging system. A Chirped Pulse Amplification (CPA) system was also designed, enabling higher amplification levels without exceeding laser damage threshold. The uniqueness of this CPA system lies in its use of a short wavelength bandwidth, ±250 pm after Self-Phase Modulation (SPM) broadening, and a line density of 1850 lines/mm for the gratings of the compressor. The pulse is stretched with a chirped fiber Bragg grating (CFBG) before amplification in Nd:YAG amplifiers, and compressed by a double pass grating compressor.
	Slides TU1C2 [7.085 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU1C2
About •	Received ※ 25 August 2023 — Revised ※ 25 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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TU1C4	The CXFEL Project at Arizona State University	electron, FEL, 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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TU4P06	The Experimental Progress for the Strong Field Terahertz Radiation at Shanghai Soft X-ray Free-electron Laser Facility	radiation, electron, undulator, FEL	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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TU4P13	An Introduction to the UK XFEL Conceptual Design and Options Analysis	FEL, photon, 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	FEL, bunching, optics, 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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TU4P28	Useful Formulas and Example Parameters Set for the Design of SSMB Storage Rings	radiation, bunching, undulator, storage-ring	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	radiation, electron, bunching, undulator	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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TU4P31	A Recursive Model for Laser-Electron-Radiation Interaction in Insertion Section of SSMB Storage Ring Based on Transverse-Longitudinal Coupling Scheme	radiation, FEL, 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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TU4P33	An Inverse-Compton Scattering Simulation Module for RF-Track	photon, scattering, simulation, HOM	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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WE3A3	Multi-FELOs Driven by a Common Electron Beam	electron, FEL, undulator, radiation	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	FEL, electron, feedback, MMI	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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WE4P15	Multichromatic Free-electron Laser Generation Through Frequency-beating in a Chirped Electron Beam	electron, FEL, 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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WE4P37	Laser Interferometer for Hall Probe Alignment and Measurement of Undulator	undulator, alignment, controls, software	215
	S.M. Khan, G. Mishra Devi Ahilya University, Indore, India M. Gehlot DESY, Hamburg, Germany S. Mishra Devi Ahilya Vishwa Vidyalaya, Institute of Engineering & Technology, Indore, India
	In the Hall probe Magnetic measurement method the field mapping is done along the length of the undulator. The field integral and phase error computed from the field mapping works as the figure of merit of the undulator. In this paper, we discuss the working of a laser interferometer for precise Hall probe alignment. A new user friendly software based on MATLAB has been developed. The phase error and magnetic field integrals are calculated for both taper and untaper U50 undulator of the Laser and Insertion Device Application (LIDA) Laboratory.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P37
About •	Received ※ 22 August 2023 — Revised ※ 22 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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WE4P38	Pulsed Wire Measurement of 20 mm Period Hybrid Undulator and Effects of Dispersion	undulator, experiment, vacuum, insertion-device	218
	S.M. Khan, G. Mishra Devi Ahilya University, Indore, India M. Gehlot DESY, Hamburg, Germany
	In the pulsed wire method, a thin wire is stretched along the undulator axis with a sensor located near the undulator end. When a current flows through the wire, the Lorentz force on the wire sets up a travelling wave that is picked up by a sensor. Sensor output v. time gives the field integral v. position along the undulator length. We investigate pulsed wire measurements of field integrals and phase error of a 20 mm-period, 500 mm-long undulator and discuss variation in performance with Hall probe data, without any dispersion correction algorithm. Dispersion in the wire introduces dispersion corrected pulse lengths for the field integral measurements. Two field integrals of the undulator were measured with an accuracy close to 2 Gcm and 2 Gcm² with the Hall probe result. The contributions of dispersion to the phase error of the undulator are analyzed. The dispersion assisted phase advance in the undulator in the pulsed wire is measured with a higher slope in comparison to the Hall probe data. Dispersion limited optical phase growth along the undulator length causes period length fluctuations and yields a discrepancy in the phase error computation in comparison to Hall probe data.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P38
About •	Received ※ 22 August 2023 — Revised ※ 22 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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WE4P39	Larmor Radius Effect on IFEL Accelerator With Staggered Undulator	undulator, electron, FEL, 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	electron, plasma, FEL, 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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TH2C2	Development of Laser-Driven Plasma Accelerator Undulator Radiation Source at ELI-Beamlines	electron, plasma, undulator, photon	237
	A.Y. Molodozhentsev Czech Republic Academy of Sciences, Institute of Physics, Prague, Czech Republic J.T. Green, P. Zimmermann ELI-BEAMS, Prague, Czech Republic A. Jancarek, S.M. Maity, A. Mondal, S.N. Niekrasz, E. Vishnyakov ELI ERIC, Dolni Brezany, Czech Republic
	Over the last decade, the mechanism of the laser-plasma acceleration of electrons was studied intensively by many experimental teams aiming to achieve high-energy, high-quality electron beams required to generate high-brilliance incoherent and, as the next step, coherent undulator photon radiation for wide-range applications. The laser-driven plasma accelerator based compact undulator radiation source is currently under commissioning at ELI-Beamlines (Institute of Physics CAS, Czech Republic) in the frame of the LUIS project, which aims to deliver stable and reliable incoherent photon beam with a wavelength around 5 nm to an user-station. As the result of this project, the electron beam parameters should be improved to generate the coherent photon radiation reaching the saturation of the photon pulse energy in a single-unit dedicated undulator (LPA-based FEL). An overview of the current status of the LUIS project will be presented, including the high-power high-repetition rate laser, acceleration of the electron beam in the plasma channel, the electron and photon beam-lines with relevant diagnostics. Challenges and future development beyond the LUIS project also being discussed.
	Slides TH2C2 [3.474 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TH2C2
About •	Received ※ 23 August 2023 — Revised ※ 29 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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TH3D3	How Can Machine Learning Help Future Light Sources?	controls, operation, electron, feedback	249
	A. Santamaria Garcia, E. Bründermann, M. Caselle, A.-S. Müller, L. Scomparin, C. Xu KIT, Karlsruhe, Germany G. De Carne Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, Germany
	Machine learning (ML) is one of the key technologies that can considerably extend and advance the capabilities of particle accelerators and needs to be included in their future design. Future light sources aim to reach unprecedented beam brightness and radiation coherence, which require challenging beam sizes and accelerating gradients. The sensitive designs and complex operation modes that arise from such demands will impact the beam availability and flexibility for the users, and can render future accelerators inefficient. ML brings a paradigm shift that can re-define how accelerators are operated. In this contribution we introduce the vision of ML-driven facilities for future accelerators, address some challenges of future light sources, and show an example of how such methods can be used to control beam instabilities.
	Slides TH3D3 [5.398 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TH3D3
About •	Received ※ 23 August 2023 — Revised ※ 25 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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TH4A2	A Compact Inverse Compton Scattering Source Based on X-band Technology and Cavity-enhanced High Average Power Ultrafast Lasers	linac, photon, electron, scattering	257
	A. Latina, R. Corsini, L.A. Dyks, E. Granados, A. Grudiev, V. Mușat, S. Stapnes, P. Wang, W. Wuensch CERN, Meyrin, Switzerland E. Cormier CELIA, Talence, France G. Santarelli ILE, Palaiseau Cedex, France
	A high-pulse-current photoinjector followed by a short high-gradient X-band linac and a Fabry-Pérot enhancement cavity are considered as a driver for a compact Inverse Compton Scattering (ICS) source. Using a high-power ultra-short pulse laser operating in burst mode in a Fabry-Pérot enhancement cavity, we show that outcoming photons with a total flux over 10¹³ and energies in the MeV range are achievable. The resulting high-intensity and high-energy photons allow various applications, including cancer therapy, tomography, and nuclear material detection. A preliminary conceptual design of such a compact ICS source and simulations of the expected performance are presented.
	Slides TH4A2 [2.962 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TH4A2
About •	Received ※ 22 August 2023 — Revised ※ 26 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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Paper

Title

Other Keywords

Page

MO2L2

Storage Ring Based Steady State Microbunching

radiation, storage-ring, electron, bunching

1

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

Powerful light sources are highly desired tools for scientific research and for industrial applications. Electrons are the objects that most readily and easily radiate photons. A natural conclusion follows that one should pursue electron accelerators as the choice tools towards powerful light sources. How to manipulate the electron beam in the accelerator so that it radiates light most efficiently, however, remains to be studied and its physical principle and technical limits be explored and optimized for the purpose. One such proposed concepts is based on the steady state microbunching (SSMB) mechanism in an electron storage ring. We make a brief introduction of the SSMB mechanism and its recent status in this presentation.

Slides MO2L2 [1.156 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO2L2

About •

Received ※ 25 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

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MO3B4

Generating High Repetition Rate X-ray Attosecond Pulses in SAPS

radiation, storage-ring, electron, dipole

22

W. Liu, X. Liu, Y. Zhao
IHEP CSNS, Guangdong Province, People’s Republic of China
Y. Jiao, X. Li, S. Wang
IHEP, Beijing, People’s Republic of China

Attosecond, which refers to 10^-18 seconds, is the timescale of electron motion within an atom. Accurate observation of electron motion helps deepen the understanding of microscopic quantum processes such as charge transfer in molecules, wave packet dynamics, and charge transfer in organic photovoltaic materials. To meet the needs of relevant research, the South Advanced Photon Source (SAPS), currently in the design phase, is considering the construction of an attosecond beamline. This paper presents relevant research on achieving high-repetition-rate coherent attosecond pulses on the fourth-generation storage ring at SAPS. Realizing attosecond pulses in a storage ring requires femtosecond to sub-femtosecond-level longitudinal modulation of the beam, and the modulation scheme needs to consider multiple factors to avoid a significant impact on other users. The study shows that with high-power, few-cycle lasers, and advanced beam modulation techniques, the photon flux of attosecond pulses can be significantly enhanced with a minimal impact on the brightness of synchrotron radiation. Adopting high-repetition-rate lasers and precise time delay control, the repetition rate of attosecond pulses at SAPS can reach the megahertz level. Currently, the design wavelength range for attosecond pulses covers the water window (2.3-4.4 nm), which is "transparent" to water but strongly absorbed by elements constituting living organisms. This wavelength range has significant application value in fields such as biology and chemistry.

Slides MO3B4 [3.400 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO3B4

About •

Received ※ 23 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

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MO3A2

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

FEL, electron, undulator, 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]

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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

FEL, 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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TU1C1

An Efficient Optimisation of a Burst Mode-Operated Fabry-Perot Cavity for Compton Light Sources

cavity, electron, photon, optics

46

V. Mușat, E. Granados, A. Latina
CERN, Meyrin, Switzerland
E. Cormier
CELIA, Talence, France
G. Santarelli
ILE, Palaiseau Cedex, France

The burst mode operation of a Fabry-Perot cavity (FPC) allows for the generation of a high-intensity photon beam in inverse Compton scattering (ICS) sources. The geometry and burst mode parameters of the FPC can be optimised to maximise the scattered photon flux. A novel optimisation method is presented, significantly improving processing speed and accuracy. The FPC’s dimensions, mirror requirements, and effective energy can be obtained from the electron beam parameters at the interaction point. A multi-objective optimization algorithm was used to derive the geometrical parameters of the FPC; this brought orders of magnitude increase in computation speed if compared to the nominal Monte Carlo-based approaches. The burst mode parameters of the FPC were obtained by maximizing the effective energy of the laser pulse in the FPC. The impact of optical losses and thermal lensing on the FPC parameters is addressed. Preliminary parameters of an ICS source implementing this novel optimisation are presented. The source could reach high-performance photon beams for high-energy applications.

Slides TU1C1 [1.776 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU1C1

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Received ※ 22 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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TU1C2

Evolution of the Inverse Compton Scattering X-ray Source of the ELSA Accelerator

electron, alignment, scattering, cavity

50

A. Pires, R. Rosch, J. Touguet
CEA, Arpajon, France
N. Delerue
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
V. Le Flanchec
CEA/DAM/DIF, Arpajon, France

The Inverse Compton Scattering (ICS) X-ray source of ELSA accelerator at CEA-DAM, presents an efficient approach for generating X-rays with a compact linac. The source consists of a 30 MeV, 15 ps rms, up to 3 nC electron beam; and a table-top Nd:YAG laser. X-rays are produced in the 10-80 keV range, higher X-ray energies achieved with frequency doubling of the laser. The yield is increased by a factor of 8 thanks to an optical mirror system developed at CEA, folding the laser beam path and accumulating successive laser pulses. We present a new version of the device, with improvement of mechanical constraints management, adjunction of motorized mirrors, and a new imaging system. A Chirped Pulse Amplification (CPA) system was also designed, enabling higher amplification levels without exceeding laser damage threshold. The uniqueness of this CPA system lies in its use of a short wavelength bandwidth, ±250 pm after Self-Phase Modulation (SPM) broadening, and a line density of 1850 lines/mm for the gratings of the compressor. The pulse is stretched with a chirped fiber Bragg grating (CFBG) before amplification in Nd:YAG amplifiers, and compressed by a double pass grating compressor.

Slides TU1C2 [7.085 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU1C2

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

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TU1C4

The CXFEL Project at Arizona State University

electron, FEL, 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

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Received ※ 30 August 2023 — Revised ※ 31 August 2023 — Accepted ※ 01 September 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, electron, undulator, FEL

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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TU4P13

An Introduction to the UK XFEL Conceptual Design and Options Analysis

FEL, photon, 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

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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

FEL, bunching, optics, 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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TU4P28

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

radiation, bunching, undulator, storage-ring

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

radiation, electron, bunching, undulator

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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TU4P31

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

radiation, FEL, 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

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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

photon, scattering, simulation, HOM

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

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

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WE3A3

Multi-FELOs Driven by a Common Electron Beam

electron, FEL, undulator, radiation

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

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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

FEL, electron, feedback, MMI

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

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Received ※ 21 August 2023 — Revised ※ 29 August 2023 — Accepted ※ 30 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, FEL, 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

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

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WE4P37

Laser Interferometer for Hall Probe Alignment and Measurement of Undulator

undulator, alignment, controls, software

215

S.M. Khan, G. Mishra
Devi Ahilya University, Indore, India
M. Gehlot
DESY, Hamburg, Germany
S. Mishra
Devi Ahilya Vishwa Vidyalaya, Institute of Engineering & Technology, Indore, India

In the Hall probe Magnetic measurement method the field mapping is done along the length of the undulator. The field integral and phase error computed from the field mapping works as the figure of merit of the undulator. In this paper, we discuss the working of a laser interferometer for precise Hall probe alignment. A new user friendly software based on MATLAB has been developed. The phase error and magnetic field integrals are calculated for both taper and untaper U50 undulator of the Laser and Insertion Device Application (LIDA) Laboratory.

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P37

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

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WE4P38

Pulsed Wire Measurement of 20 mm Period Hybrid Undulator and Effects of Dispersion

undulator, experiment, vacuum, insertion-device

218

S.M. Khan, G. Mishra
Devi Ahilya University, Indore, India
M. Gehlot
DESY, Hamburg, Germany

In the pulsed wire method, a thin wire is stretched along the undulator axis with a sensor located near the undulator end. When a current flows through the wire, the Lorentz force on the wire sets up a travelling wave that is picked up by a sensor. Sensor output v. time gives the field integral v. position along the undulator length. We investigate pulsed wire measurements of field integrals and phase error of a 20 mm-period, 500 mm-long undulator and discuss variation in performance with Hall probe data, without any dispersion correction algorithm. Dispersion in the wire introduces dispersion corrected pulse lengths for the field integral measurements. Two field integrals of the undulator were measured with an accuracy close to 2 Gcm and 2 Gcm² with the Hall probe result. The contributions of dispersion to the phase error of the undulator are analyzed. The dispersion assisted phase advance in the undulator in the pulsed wire is measured with a higher slope in comparison to the Hall probe data. Dispersion limited optical phase growth along the undulator length causes period length fluctuations and yields a discrepancy in the phase error computation in comparison to Hall probe data.

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P38

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

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WE4P39

Larmor Radius Effect on IFEL Accelerator With Staggered Undulator

undulator, electron, FEL, 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

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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

electron, plasma, FEL, 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

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

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TH2C2

Development of Laser-Driven Plasma Accelerator Undulator Radiation Source at ELI-Beamlines

electron, plasma, undulator, photon

237

A.Y. Molodozhentsev
Czech Republic Academy of Sciences, Institute of Physics, Prague, Czech Republic
J.T. Green, P. Zimmermann
ELI-BEAMS, Prague, Czech Republic
A. Jancarek, S.M. Maity, A. Mondal, S.N. Niekrasz, E. Vishnyakov
ELI ERIC, Dolni Brezany, Czech Republic

Over the last decade, the mechanism of the laser-plasma acceleration of electrons was studied intensively by many experimental teams aiming to achieve high-energy, high-quality electron beams required to generate high-brilliance incoherent and, as the next step, coherent undulator photon radiation for wide-range applications. The laser-driven plasma accelerator based compact undulator radiation source is currently under commissioning at ELI-Beamlines (Institute of Physics CAS, Czech Republic) in the frame of the LUIS project, which aims to deliver stable and reliable incoherent photon beam with a wavelength around 5 nm to an user-station. As the result of this project, the electron beam parameters should be improved to generate the coherent photon radiation reaching the saturation of the photon pulse energy in a single-unit dedicated undulator (LPA-based FEL). An overview of the current status of the LUIS project will be presented, including the high-power high-repetition rate laser, acceleration of the electron beam in the plasma channel, the electron and photon beam-lines with relevant diagnostics. Challenges and future development beyond the LUIS project also being discussed.

Slides TH2C2 [3.474 MB]

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TH2C2

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

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TH3D3

How Can Machine Learning Help Future Light Sources?

controls, operation, electron, feedback

249

A. Santamaria Garcia, E. Bründermann, M. Caselle, A.-S. Müller, L. Scomparin, C. Xu
KIT, Karlsruhe, Germany
G. De Carne
Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, Germany

Machine learning (ML) is one of the key technologies that can considerably extend and advance the capabilities of particle accelerators and needs to be included in their future design. Future light sources aim to reach unprecedented beam brightness and radiation coherence, which require challenging beam sizes and accelerating gradients. The sensitive designs and complex operation modes that arise from such demands will impact the beam availability and flexibility for the users, and can render future accelerators inefficient. ML brings a paradigm shift that can re-define how accelerators are operated. In this contribution we introduce the vision of ML-driven facilities for future accelerators, address some challenges of future light sources, and show an example of how such methods can be used to control beam instabilities.

Slides TH3D3 [5.398 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-TH3D3

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Received ※ 23 August 2023 — Revised ※ 25 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

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TH4A2

A Compact Inverse Compton Scattering Source Based on X-band Technology and Cavity-enhanced High Average Power Ultrafast Lasers

linac, photon, electron, scattering

257

A. Latina, R. Corsini, L.A. Dyks, E. Granados, A. Grudiev, V. Mușat, S. Stapnes, P. Wang, W. Wuensch
CERN, Meyrin, Switzerland
E. Cormier
CELIA, Talence, France
G. Santarelli
ILE, Palaiseau Cedex, France

A high-pulse-current photoinjector followed by a short high-gradient X-band linac and a Fabry-Pérot enhancement cavity are considered as a driver for a compact Inverse Compton Scattering (ICS) source. Using a high-power ultra-short pulse laser operating in burst mode in a Fabry-Pérot enhancement cavity, we show that outcoming photons with a total flux over 10¹³ and energies in the MeV range are achievable. The resulting high-intensity and high-energy photons allow various applications, including cancer therapy, tomography, and nuclear material detection. A preliminary conceptual design of such a compact ICS source and simulations of the expected performance are presented.

Slides TH4A2 [2.962 MB]

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TH4A2

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Received ※ 22 August 2023 — Revised ※ 26 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

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