FLS2023 - List of Keywords (bunching)

Paper	Title	Other Keywords	Page
MO2L2	Storage Ring Based Steady State Microbunching	radiation, laser, storage-ring, electron	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)

TU4P16	Transverse Optics-based Control of the Microbunching Instability	FEL, optics, laser, electron	107
	A.D. Brynes, E. Allaria, G. De Ninno, S. Di Mitri, D. Garzella, C. Spezzani Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy G. De Ninno University of Nova Gorica, Nova Gorica, Slovenia G. Perosa Università degli Studi di Trieste, Trieste, Italy C.-Y. Tsai HUST, Wuhan, People’s Republic of China
	A number of recent experimental and theoretical studies have investigated novel techniques for suppressing the microbunching instability in high-brightness linac-based light sources. This instability has long been studied as one of the causes of reduced longitudinal coherence in these machines, which are commonly suppressed using a laser heater. This contribution presents recent developments concerning the use of an optics-based scheme to mitigate the microbunching instability in the FERMI free-electron laser, paving the way towards reversible beam heating techniques that could improve the performance of future machines.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P16
About •	Received ※ 23 August 2023 — Revised ※ 29 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TU4P28	Useful Formulas and Example Parameters Set for the Design of SSMB Storage Rings	radiation, laser, 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
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TU4P29	Why is the Coherent Radiation from Laser-induced Microbunches Narrowbanded and Collimated	radiation, electron, laser, 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
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TU4P31	A Recursive Model for Laser-Electron-Radiation Interaction in Insertion Section of SSMB Storage Ring Based on Transverse-Longitudinal Coupling Scheme	laser, radiation, FEL, storage-ring	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
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WE4P15	Multichromatic Free-electron Laser Generation Through Frequency-beating in a Chirped Electron Beam	electron, FEL, laser, 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
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

MO2L2

Storage Ring Based Steady State Microbunching

radiation, laser, storage-ring, electron

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)

TU4P16

Transverse Optics-based Control of the Microbunching Instability

FEL, optics, laser, electron

107

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

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

DOI •

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

About •

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

Cite •

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

TU4P28

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

radiation, laser, 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

Cite •

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

TU4P29

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

radiation, electron, laser, 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

Cite •

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

TU4P31

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

laser, radiation, FEL, storage-ring

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

Cite •

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

WE4P15

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

electron, FEL, laser, 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

Cite •

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