FLS2023 - List of Keywords (radiation)

Paper	Title	Other Keywords	Page
MO2L2	Storage Ring Based Steady State Microbunching	laser, 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
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MO3B4	Generating High Repetition Rate X-ray Attosecond Pulses in SAPS	storage-ring, laser, 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
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TU4P06	The Experimental Progress for the Strong Field Terahertz Radiation at Shanghai Soft X-ray Free-electron Laser Facility	laser, 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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TU4P11	Symmetric Compton Scattering: A Way Towards Plasma Heating and Tunable Mono-chromatic Gamma-rays	electron, photon, scattering, plasma	95
	L. Serafini, A. Bacci, I. Drebot, M. Rossetti Conti, S. Samsam INFN-Milano, Milano, Italy C. Curatolo INFN- Sez. di Padova, Padova, Italy V. Petrillo, A. Puppin Universita’ degli Studi di Milano & INFN, Milano, Italy
	We analyze the transition between Compton Scattering and Inverse Compton Scattering (ICS), characterized by an equal exchange of energy and momentum between the colliding particles (electrons and photons). In this Symmetric Compton Scattering (SCS) regime, the energy-angle correlation of scattered photons is cancelled, and, when the electron recoil is large, monochromaticity is transferred from one colliding beam to the other. Large-recoil SCS or quasi-SCS can be used to design compact intrinsic monochromatic γ-ray sources based on compact linacs, thus avoiding the use of GeV-class electron beams and powerful laser/optical systems as required for ICS sources. At very low recoil and energy collisions (about 10 keV energy range), SCS can be exploited to heat the colliding electron beam, which is scattered with large transverse momenta over the entire solid angle, offering a technique to trap electrons into magnetic bottles for plasma heating.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P11
About •	Received ※ 24 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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TU4P28	Useful Formulas and Example Parameters Set for the Design of SSMB Storage Rings	laser, 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	electron, laser, 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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TU4P30	Optical Stochastic Cooling in a General Coupled Lattice	damping, undulator, pick-up, storage-ring	143
	X.J. Deng TUB, Beijing, People’s Republic of China
	Here we present a formalism of optical stochastic cooling in a 3D general coupled lattice. The formalism is general, and can treat a variety of damping and diffusion mechanisms within a single framework. We expect the work to be of value for the development of future light source.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P30
About •	Received ※ 15 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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TU4P31	A Recursive Model for Laser-Electron-Radiation Interaction in Insertion Section of SSMB Storage Ring Based on Transverse-Longitudinal Coupling Scheme	laser, 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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WE3A3	Multi-FELOs Driven by a Common Electron Beam	electron, FEL, undulator, 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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WE4P09	Heat Load and Radiation Pulse of Corrugated Structure at SHINE Facility	simulation, wakefield, linac, electron	168
	J.J. Guo Zhangjiang Lab, Shanghai, People’s Republic of China H.X. Deng, D. Gu, Q. Gu, M. Meng, Z. Wang SARI-CAS, Pudong, Shanghai, People’s Republic of China
	Corrugated structure modules are being proposed for installation after the end of the linac and before the undulator regions of SHINE facility, where it has been used for energy chirp control and as a fast kicker for two color operation of the FEL. When ultra-relativistic bunch of electrons passing through corrugated structure will generate strong wakefield, we find most of the wake power lost by the beam is radiated out to the sides of the corrugated structure in the form of THz waves, and the remaining part casue Joule heating load on the corrugated structure wall. In this paper, we estimate the radiation pulse power and Joule power loss of the corrugated structure in SHINE facility.
	Poster WE4P09 [0.787 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P09
About •	Received ※ 23 August 2023 — Revised ※ 28 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, FEL, undulator, 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, FEL, laser, bunching	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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WE4P18	Preliminary Design of Higher-order Achromat Lattice for the Upgrade of the Taiwan Photon Source	lattice, emittance, dipole, storage-ring	184
	N.Y. Huang, M.-S. Chiu, P.J. Chou, G.-H. Luo, H.W. Luo, H.-J. Tsai, F.H. Tseng NSRRC, Hsinchu, Taiwan
	We study the upgrade of Taiwan Photon Source (TPS) with energy saving as the prime objective. The upgrade design is dubbed TPS-II. To accommodate the constraints imposed by the existing TPS tunnel, we choose the higher-order achromat (HOA) lattice configuration which is composed of the 5BA and 4BA cells. This HOA lattice produces a natural beam emittance about 131 pm-rad for a 3 GeV, 518.4 m storage ring. The on-momentum dynamic aperture is about 8 mm and the estimated Touschek life time reaches around 5.7 hours at total beam current of 500 mA. As a result of the ultralow beam emittance, the brightness and coherence fraction (CF) of the photon beam are improved with a factor of several tens especially in the photon wavelength around 0.1 nm. The challenges and preliminary results of this HOA lattice design will be presented.
	Poster WE4P18 [5.398 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P18
About •	Received ※ 21 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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WE4P39	Larmor Radius Effect on IFEL Accelerator With Staggered Undulator	undulator, electron, laser, FEL	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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TH1D4	Bi-periodic Undulator: Innovative Insertion Device for SOLEIL II	undulator, synchrotron, electron, storage-ring	228
	A. Potet, F. Blache, P. Brunelle, M.-E. Couprie, O. Marcouillé, A. Mary, T. Mutin, A. Nadji, K. Tavakoli, C. de Oliveira SOLEIL, Gif-sur-Yvette, France
	SOLEIL II project will lead to optimize the production of photons by a modification of the present facility. The storage ring will be redesigned to reduce electron beam emittance, increase photon beam flux and brightness, and improve beamline resolution. The number of magnetic elements will be increased and the space reserved for insertion devices will be decreased by 30%. SOLEIL magnetic group searches for solutions to generate different magnetic periods in a smaller space to maintain the full spectral domain. Bi-Periodic undulator is an innovative and compact device allowing the use of two selectable magnetic periodicities by superimposition of magnets. The magnetic period can be switched from one value to its triple value by mechanical shift of magnetic arrays. A magnetic design has been performed and the construction of a prototype, including magnetic measurements and corrections, is under progress. The prototype will be installed in the storage ring with the goal to verify the feasibility of the model and to characterize the system. The magnetic fields, the radiation produced and the electron beam dynamics will be considered to have a complete knowledge on this undulator.
	Slides TH1D4 [2.442 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TH1D4
About •	Received ※ 23 August 2023 — Revised ※ 26 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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TH3D2	Radiation Protection Issues in Undulator Upgrades for the European XFEL	undulator, photon, simulation, FEL	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, FEL, 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

MO2L2

Storage Ring Based Steady State Microbunching

laser, 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

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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

storage-ring, laser, 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]

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

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

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TU4P06

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

laser, 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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TU4P11

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

electron, photon, scattering, plasma

95

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

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

DOI •

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

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

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TU4P28

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

laser, 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

electron, laser, 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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TU4P30

Optical Stochastic Cooling in a General Coupled Lattice

damping, undulator, pick-up, storage-ring

143

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

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

DOI •

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

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

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TU4P31

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

laser, 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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WE3A3

Multi-FELOs Driven by a Common Electron Beam

electron, FEL, undulator, 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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WE4P09

Heat Load and Radiation Pulse of Corrugated Structure at SHINE Facility

simulation, wakefield, linac, electron

168

J.J. Guo
Zhangjiang Lab, Shanghai, People’s Republic of China
H.X. Deng, D. Gu, Q. Gu, M. Meng, Z. Wang
SARI-CAS, Pudong, Shanghai, People’s Republic of China

Corrugated structure modules are being proposed for installation after the end of the linac and before the undulator regions of SHINE facility, where it has been used for energy chirp control and as a fast kicker for two color operation of the FEL. When ultra-relativistic bunch of electrons passing through corrugated structure will generate strong wakefield, we find most of the wake power lost by the beam is radiated out to the sides of the corrugated structure in the form of THz waves, and the remaining part casue Joule heating load on the corrugated structure wall. In this paper, we estimate the radiation pulse power and Joule power loss of the corrugated structure in SHINE facility.

Poster WE4P09 [0.787 MB]

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P09

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Received ※ 23 August 2023 — Revised ※ 28 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, FEL, undulator, 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

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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, FEL, laser, bunching

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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WE4P18

Preliminary Design of Higher-order Achromat Lattice for the Upgrade of the Taiwan Photon Source

lattice, emittance, dipole, storage-ring

184

N.Y. Huang, M.-S. Chiu, P.J. Chou, G.-H. Luo, H.W. Luo, H.-J. Tsai, F.H. Tseng
NSRRC, Hsinchu, Taiwan

We study the upgrade of Taiwan Photon Source (TPS) with energy saving as the prime objective. The upgrade design is dubbed TPS-II. To accommodate the constraints imposed by the existing TPS tunnel, we choose the higher-order achromat (HOA) lattice configuration which is composed of the 5BA and 4BA cells. This HOA lattice produces a natural beam emittance about 131 pm-rad for a 3 GeV, 518.4 m storage ring. The on-momentum dynamic aperture is about 8 mm and the estimated Touschek life time reaches around 5.7 hours at total beam current of 500 mA. As a result of the ultralow beam emittance, the brightness and coherence fraction (CF) of the photon beam are improved with a factor of several tens especially in the photon wavelength around 0.1 nm. The challenges and preliminary results of this HOA lattice design will be presented.

Poster WE4P18 [5.398 MB]

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P18

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

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WE4P39

Larmor Radius Effect on IFEL Accelerator With Staggered Undulator

undulator, electron, laser, FEL

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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TH1D4

Bi-periodic Undulator: Innovative Insertion Device for SOLEIL II

undulator, synchrotron, electron, storage-ring

228

A. Potet, F. Blache, P. Brunelle, M.-E. Couprie, O. Marcouillé, A. Mary, T. Mutin, A. Nadji, K. Tavakoli, C. de Oliveira
SOLEIL, Gif-sur-Yvette, France

SOLEIL II project will lead to optimize the production of photons by a modification of the present facility. The storage ring will be redesigned to reduce electron beam emittance, increase photon beam flux and brightness, and improve beamline resolution. The number of magnetic elements will be increased and the space reserved for insertion devices will be decreased by 30%. SOLEIL magnetic group searches for solutions to generate different magnetic periods in a smaller space to maintain the full spectral domain. Bi-Periodic undulator is an innovative and compact device allowing the use of two selectable magnetic periodicities by superimposition of magnets. The magnetic period can be switched from one value to its triple value by mechanical shift of magnetic arrays. A magnetic design has been performed and the construction of a prototype, including magnetic measurements and corrections, is under progress. The prototype will be installed in the storage ring with the goal to verify the feasibility of the model and to characterize the system. The magnetic fields, the radiation produced and the electron beam dynamics will be considered to have a complete knowledge on this undulator.

Slides TH1D4 [2.442 MB]

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TH1D4

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Received ※ 23 August 2023 — Revised ※ 26 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

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TH3D2

Radiation Protection Issues in Undulator Upgrades for the European XFEL

undulator, photon, simulation, FEL

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, FEL, 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]

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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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