IPAC2019 - List of Authors (Yan, L.G.)

Paper	Title	Page
TUPRB052	The Mini-Period Permanent Magnet Staggered Undulator for Compact X-Ray Free Electron Laser	1797
	L.G. Yan, D.R. Deng, J. Wang CAEP/IAE, Mianyang, Sichuan, People’s Republic of China
	Funding: Work supported by National Natural Science Foundation of China under grant of 11505174, 11505173 and 11605190. Miniaturization of X-ray free electron laser requires reduction of undulator period length. In this proceeding, a mini-period permanent magnet staggered undulator was proposed, which is free of superconducting solenoid and thus has advantages of easy-manufacture and low-cost. After optimization, it can generate periodic field of peak field 0.71 T with period length 10 mm and pole gap 2 mm, which has been verified on a prototype. Combined with X-band linac, the length of 1 nm XFEL facility using the permanent magnet staggered undulator can be confined within 44 m.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB052
About •	paper received ※ 30 April 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019
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WEPGW055	Beam Longitudinal Distribution Reconstructed by GESPAR Method at CAEP THz FEL	2602
	D. Wu, T.H. He, P. Li, J. Liu, X. Luo, Q. Pan, L.J. Shan, X. Shen, J. Wang, D.X. Xiao, L.G. Yan, P. Zhang, K. Zhou CAEP/IAE, Mianyang, Sichuan, People’s Republic of China
	Funding: Work supported by National Natural Science Foundation of China with grant (11505173, 11505174, 11575264, and 11605190) Coherent radiation can be used to measure the longitudinal distribution of the electron beam bunch of any length, as long as the coherent radiation spectrum can be measured. In many cases, the Kramers-Krönig relationship is used to reconstruct the temporal distribution of the beam from the coherent radiation spectrum. However, the extrapolation of the low frequency will introduce the uncertainty of the reconstruction. In this paper, GrEedy Sparse PhAse Retrieval (GESPAR) method was used to reconstruct the beam longitudinal distribution measured by coherent transition radiation on the THz FEL facility of China Academy of Engineering Physics. The results indicate that the GESPAR method works well for the complex and ultrashort distribution. It will be an effective tool to accurately measure the femtosecond bunch temporal structure.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW055
About •	paper received ※ 14 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019
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THPRB054	Design of a Ultrafast Stripline Kicker for Bunch-by-Bunch Feedback	3931
	J. Wang, P. Li, D. Wu, D.X. Xiao, L.G. Yan CAEP/IAE, Mianyang, Sichuan, People’s Republic of China
	Lorentz force detuning and beam loading effect of the rf cavities will induce a slope of the cavity gradient. Combed with the cavity misalignments, transverse position of subsequent bunches will differ from each other. The CAEP THz Free Electron Laser facility(CTFEL) will have a fast transverse bunch-by-bunch feedback system on its test beamline, which is used to correct the beam position differences of individual bunches in the macro-pulses. The time response of the kicker is rigid for the interval of the micro-pulses is 18.5ns and will upgrade to about 2 ns, requiring impedance matching of the kicker with the power source and transmission system in a high bandwidth. Also, the electromagnetic field must reach the requirements of the beam parameters. In this paper, the structure design and the optimization of the geometric parameters of the ultrafast stripline kicker is presented. The characteristic impedance, transmission characteristics, field consistency are analyzed and optimized. And the feedback signal generation scheme for continuous bunch trains was proposed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB054
About •	paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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THPTS029	Optimization of Staggered Array Undulator	4171
	L.J. Chen, Q.K. Jia USTC/NSRL, Hefei, Anhui, People’s Republic of China M. Li, P. Li, J. Wang, D. Wu, D.X. Xiao, L.G. Yan, X. Yang CAEP/IAE, Mianyang, Sichuan, People’s Republic of China
	Funding: the National Key Research and Development Program of China under Grant No. 2016YFA0402003 the National Nature Science Foundation of China under Grant No. 11611140102. The staggered array undulator consists of staggered poles and solenoid coils that form a periodically aligned transverse magnetic field in the pole gap. The addition of magnets in the longitudinal gap between the poles further enhances the peak field strength of the undulator. A method of enhancing the peak field strength of the undulator using cryogenic temperature permanent magnets and adding side magnets has been studied. The remanence of the magnet will increase at low temperatures and the peak field strength of the undulator will increase. The side magnets do not increase the maximum peak field strength of the undulator, but can reduce the solenoid magnetic field requirements and reduce the solenoid volume and cost. The influence of the special magnetic pole and magnet shape on the peak field strength of the undulator has also been studied.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS029
About •	paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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Paper

Title

Page

The Mini-Period Permanent Magnet Staggered Undulator for Compact X-Ray Free Electron Laser

1797

L.G. Yan, D.R. Deng, J. Wang
CAEP/IAE, Mianyang, Sichuan, People’s Republic of China

Funding: Work supported by National Natural Science Foundation of China under grant of 11505174, 11505173 and 11605190.
Miniaturization of X-ray free electron laser requires reduction of undulator period length. In this proceeding, a mini-period permanent magnet staggered undulator was proposed, which is free of superconducting solenoid and thus has advantages of easy-manufacture and low-cost. After optimization, it can generate periodic field of peak field 0.71 T with period length 10 mm and pole gap 2 mm, which has been verified on a prototype. Combined with X-band linac, the length of 1 nm XFEL facility using the permanent magnet staggered undulator can be confined within 44 m.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB052

About •

paper received ※ 30 April 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

Export •

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

WEPGW055

Beam Longitudinal Distribution Reconstructed by GESPAR Method at CAEP THz FEL

2602

D. Wu, T.H. He, P. Li, J. Liu, X. Luo, Q. Pan, L.J. Shan, X. Shen, J. Wang, D.X. Xiao, L.G. Yan, P. Zhang, K. Zhou
CAEP/IAE, Mianyang, Sichuan, People’s Republic of China

Funding: Work supported by National Natural Science Foundation of China with grant (11505173, 11505174, 11575264, and 11605190)
Coherent radiation can be used to measure the longitudinal distribution of the electron beam bunch of any length, as long as the coherent radiation spectrum can be measured. In many cases, the Kramers-Krönig relationship is used to reconstruct the temporal distribution of the beam from the coherent radiation spectrum. However, the extrapolation of the low frequency will introduce the uncertainty of the reconstruction. In this paper, GrEedy Sparse PhAse Retrieval (GESPAR) method was used to reconstruct the beam longitudinal distribution measured by coherent transition radiation on the THz FEL facility of China Academy of Engineering Physics. The results indicate that the GESPAR method works well for the complex and ultrashort distribution. It will be an effective tool to accurately measure the femtosecond bunch temporal structure.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW055

About •

paper received ※ 14 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019

Export •

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

THPRB054

Design of a Ultrafast Stripline Kicker for Bunch-by-Bunch Feedback

3931

J. Wang, P. Li, D. Wu, D.X. Xiao, L.G. Yan
CAEP/IAE, Mianyang, Sichuan, People’s Republic of China

Lorentz force detuning and beam loading effect of the rf cavities will induce a slope of the cavity gradient. Combed with the cavity misalignments, transverse position of subsequent bunches will differ from each other. The CAEP THz Free Electron Laser facility(CTFEL) will have a fast transverse bunch-by-bunch feedback system on its test beamline, which is used to correct the beam position differences of individual bunches in the macro-pulses. The time response of the kicker is rigid for the interval of the micro-pulses is 18.5ns and will upgrade to about 2 ns, requiring impedance matching of the kicker with the power source and transmission system in a high bandwidth. Also, the electromagnetic field must reach the requirements of the beam parameters. In this paper, the structure design and the optimization of the geometric parameters of the ultrafast stripline kicker is presented. The characteristic impedance, transmission characteristics, field consistency are analyzed and optimized. And the feedback signal generation scheme for continuous bunch trains was proposed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB054

About •

paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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

THPTS029

Optimization of Staggered Array Undulator

4171

L.J. Chen, Q.K. Jia
USTC/NSRL, Hefei, Anhui, People’s Republic of China
M. Li, P. Li, J. Wang, D. Wu, D.X. Xiao, L.G. Yan, X. Yang
CAEP/IAE, Mianyang, Sichuan, People’s Republic of China

Funding: the National Key Research and Development Program of China under Grant No. 2016YFA0402003 the National Nature Science Foundation of China under Grant No. 11611140102.
The staggered array undulator consists of staggered poles and solenoid coils that form a periodically aligned transverse magnetic field in the pole gap. The addition of magnets in the longitudinal gap between the poles further enhances the peak field strength of the undulator. A method of enhancing the peak field strength of the undulator using cryogenic temperature permanent magnets and adding side magnets has been studied. The remanence of the magnet will increase at low temperatures and the peak field strength of the undulator will increase. The side magnets do not increase the maximum peak field strength of the undulator, but can reduce the solenoid magnetic field requirements and reduce the solenoid volume and cost. The influence of the special magnetic pole and magnet shape on the peak field strength of the undulator has also been studied.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS029

About •

paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

Export •

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