FEL2019 - List of Authors (Chao, A.)

Paper	Title	Page
THP020	Microbunching Enhancement by Adiabatic Trapping	635
	X.J. Deng, W.-H. Huang, C.-X. Tang TUB, Beijing, People’s Republic of China A. Chao SLAC, Menlo Park, California, USA
	Storage ring based concept called steady-state microbunching was proposed years ago for high average power narrowband coherent radiation generation. There are now active efforts on-going by the SSMB collaboration established among Tsinghua University and several other institutes. In this paper we study the particle trap and filamentation process of beam in RF or Micro Bucket which is useful for understanding the injection beam dynamics of SSMB. One remarkable result is the steady-state current distribution after full filamentation has little dependence on the bucket height as long as it is several times larger than the energy spread. A discrete increase of bucket height can boost the bunching, with the sacrifice of emittance growth. An adiabatic change of bucket height from a smaller value to the final desired value is then proposed to boost the bunching while preserving the longitudinal emittance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP020
About •	paper received ※ 20 August 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019
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THP030	An Updated Design of the NSRRC Seeded VUV Free Electron Laser Test Facility	651
	W.K. Lau, C.K. Chan, C.-H. Chang, C.-C. Chang, L.-H. Chang, C.H. Chen, M.C. Chou, P.J. Chou, F.Z. Hsiao, K.T. Hsu, H.P. Hsueh, K.H. Hu, C.-S. Hwang, J.-Y. Hwang, J.C. Jan, C.K. Kuan, A.P. Lee, M.-C. Lin, G.-H. Luo, K.L. Tsai NSRRC, Hsinchu, Taiwan A. Chao, J. Wu SLAC, Menlo Park, California, USA S.Y. Teng NTHU, Hsinchu, Taiwan
	In this report, we present an updated design of the facility which is a 200 nm seeded, HGHG FEL driven by a 250 MeV high brightness electron linac system with dogleg bunch compressor for generation of ultrashort intense coherent radiation in the vacuum ultraviolet region. It employs a 10-periods helical undulator for enhancement of beam energy modulation and a helical undulator of 20 mm period length as the radiator (i.e. THU20) to produce hundreds of megawatts radiation with wavelength as short as 66.7 nm. An optional planar undulator can be added to generate odd harmonics (e.g. 22.2 nm, 13.3 nm etc.) of the fundamental. The facility layout and expected FEL output performance is reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP030
About •	paper received ※ 20 August 2019 paper accepted ※ 29 August 2019 issue date ※ 05 November 2019
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THP055	A Storage Ring Design for Steady-State Microbunching to Generate Coherent EUV Light Source	700
	Z. Pan, X.J. Deng, W.-H. Huang, T. Rui, C.-X. Tang, Y. Zhang TUB, Beijing, People’s Republic of China A. Chao SLAC, Menlo Park, California, USA W. Wan ShanghaiTech University, Shanghai, People’s Republic of China
	The proposal of Steady State Microbunching (SSMB) makes it available to generate high average power coherent radiation, especially has the potential to generate kW level of EUV source for lithography. In order to achieve and maintain SSMB, we propose several concepts. One is that a very short electron bunch below 100 nm is stored in the ring, inserting a strong focusing part to compress the bunch to ~3 nm, then radiating coherently, which is called longitudinal strong focusing (LSF) scheme. We have optimized the candidate lattice to achieve the very short electron bunch storage and microbunching for electron beam. The tracking results show the equilibrium length of the electron bunch is about 400 nm and no particles lose after 4.3 damping time while only single-particle effect is considered. More optimization and some new design based on the simulation results are still implementing.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP055
About •	paper received ※ 19 August 2019 paper accepted ※ 26 August 2019 issue date ※ 05 November 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Microbunching Enhancement by Adiabatic Trapping

635

X.J. Deng, W.-H. Huang, C.-X. Tang
TUB, Beijing, People’s Republic of China
A. Chao
SLAC, Menlo Park, California, USA

Storage ring based concept called steady-state microbunching was proposed years ago for high average power narrowband coherent radiation generation. There are now active efforts on-going by the SSMB collaboration established among Tsinghua University and several other institutes. In this paper we study the particle trap and filamentation process of beam in RF or Micro Bucket which is useful for understanding the injection beam dynamics of SSMB. One remarkable result is the steady-state current distribution after full filamentation has little dependence on the bucket height as long as it is several times larger than the energy spread. A discrete increase of bucket height can boost the bunching, with the sacrifice of emittance growth. An adiabatic change of bucket height from a smaller value to the final desired value is then proposed to boost the bunching while preserving the longitudinal emittance.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP020

About •

paper received ※ 20 August 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019

Export •

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

THP030

An Updated Design of the NSRRC Seeded VUV Free Electron Laser Test Facility

651

W.K. Lau, C.K. Chan, C.-H. Chang, C.-C. Chang, L.-H. Chang, C.H. Chen, M.C. Chou, P.J. Chou, F.Z. Hsiao, K.T. Hsu, H.P. Hsueh, K.H. Hu, C.-S. Hwang, J.-Y. Hwang, J.C. Jan, C.K. Kuan, A.P. Lee, M.-C. Lin, G.-H. Luo, K.L. Tsai
NSRRC, Hsinchu, Taiwan
A. Chao, J. Wu
SLAC, Menlo Park, California, USA
S.Y. Teng
NTHU, Hsinchu, Taiwan

In this report, we present an updated design of the facility which is a 200 nm seeded, HGHG FEL driven by a 250 MeV high brightness electron linac system with dogleg bunch compressor for generation of ultrashort intense coherent radiation in the vacuum ultraviolet region. It employs a 10-periods helical undulator for enhancement of beam energy modulation and a helical undulator of 20 mm period length as the radiator (i.e. THU20) to produce hundreds of megawatts radiation with wavelength as short as 66.7 nm. An optional planar undulator can be added to generate odd harmonics (e.g. 22.2 nm, 13.3 nm etc.) of the fundamental. The facility layout and expected FEL output performance is reported.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP030

About •

paper received ※ 20 August 2019 paper accepted ※ 29 August 2019 issue date ※ 05 November 2019

Export •

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

THP055

A Storage Ring Design for Steady-State Microbunching to Generate Coherent EUV Light Source

700

Z. Pan, X.J. Deng, W.-H. Huang, T. Rui, C.-X. Tang, Y. Zhang
TUB, Beijing, People’s Republic of China
A. Chao
SLAC, Menlo Park, California, USA
W. Wan
ShanghaiTech University, Shanghai, People’s Republic of China

The proposal of Steady State Microbunching (SSMB) makes it available to generate high average power coherent radiation, especially has the potential to generate kW level of EUV source for lithography. In order to achieve and maintain SSMB, we propose several concepts. One is that a very short electron bunch below 100 nm is stored in the ring, inserting a strong focusing part to compress the bunch to ~3 nm, then radiating coherently, which is called longitudinal strong focusing (LSF) scheme. We have optimized the candidate lattice to achieve the very short electron bunch storage and microbunching for electron beam. The tracking results show the equilibrium length of the electron bunch is about 400 nm and no particles lose after 4.3 damping time while only single-particle effect is considered. More optimization and some new design based on the simulation results are still implementing.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP055

About •

paper received ※ 19 August 2019 paper accepted ※ 26 August 2019 issue date ※ 05 November 2019

Export •

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