IPAC2016 - List of Authors (Xu, G.)

Paper	Title	Page
MOPOW020	Power Improvement of Free-Electron Laser Using Transverse-Gradient Undulator with External Focusing	760
	G. Zhou, Y. Jiao, G. Xu IHEP, Beijing, People's Republic of China J. Wu SLAC, Menlo Park, California, USA T. Zhang SINAP, Shanghai, People's Republic of China
	Funding: Supported by National Natural Science Foundation of China (11475202, 11405187) and Youth Innovation Promotion Association of Chinese Academy of Sciences (No. 2015009) Resent study [Z. Huang et al., Phys. Rev. Lett. 10⁹, 204801 (2012)] shows that the transverse-gradient undu-lator (TGU) together with electron beams with constant dispersion can reduce the sensitivity to energy spread for FEL. In this study, we numerically study FEL using TGU with external focusing. In spite of the dispersion varia-tion, through parameter optimization, FEL using TGU with TGU achieves similar radiation to that without ex-ternal focusing. To achieve a high energy exaction effi-ciency, the initial dispersion should be set with a shift from that corresponding to the resonant condition, and a variation of the transverse gradient in different undulator section is preferred. Other approaches, such as tapering and detuning frequency control, are also discussed to further improve the radiation power and are demonstrated with global parametric optimizations base on simulation.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW020
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TUYA01	BEPCII Performance and Beam Dynamics Studies on Luminosity	1014
	C.H. Yu, Z. Duan, S. Gu, Y.Y. Guo, X.Y. Huang, D. Ji, H.F. Ji, Y. Jiao, Zh.C. Liu, Y.M. Peng, Q. Qin, Y.S. Sun, S.K. Tian, J.Q. Wang, N. Wang, X.H. Wang, Y. Wei, X.M. Wen, J. Wu, J. Xing, G. Xu, Y. Yue, C. Zhang, Y. Zhang IHEP, Beijing, People's Republic of China
	The upgrade of the Beijing Electron Positron Collider, BEPCII, is now in a good performance for both high energy physics and synchrotron radiation experiments. The luminosity at the design energy of 1.89 GeV reached the design value 1.0*10³³/cm²/s¹ recently. A lot of work, including accelerator physics study and technical progress, has been done for the luminosity enhancement, not only at the design energy, but all the energy region run for HEP experiments from 1.0 to 2.3 GeV. The performance of BEPCII and the process of luminosity enhancement will be described in detail.
	Slides TUYA01 [5.801 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUYA01
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WEOAA02	On-axis Beam Accumulation Enabled by Phase Adjustment of a Double-frequency RF System for Diffraction-limited Storage Rings	2032
	G. Xu, J. Chen, Z. Duan, J. Qiu IHEP, Beijing, People's Republic of China
	Funding: Work supported by NSFC (Y4113G005C) Future synchrotron light sources aim to achieve ultra- low emittances on both transverse planes, approaching or even reaching the diffraction limit of X-ray photon energies. These diffraction-limited storage rings (DLSRs) feature very strong lattice nonlinearities and thus very small dynamic aperture, which exclude off-axis injection schemes. In this paper, we propose a longitudinal on-axis injection scheme, which is based on a double-frequency RF system and in- dependently adjustment of the RF phase of each cavity to enable RF gymnastics. Such a scheme looks feasible with the state-of-art technology of fast injection kicker. Compari- son with other on-axis injection schemes is also discussed.
	Slides WEOAA02 [1.712 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEOAA02
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WEPOW025	Exploring the Ultimate Linear and Nonlinear Performance of the HEPS hybrid 7BA design	2883
	Y. Jiao, G. Xu IHEP, Beijing, People's Republic of China
	The High Energy Photon Source (HEPS), a kilometre- scale diffraction-limited storage ring (DLSR) light source, with a beam energy of 5 to 6 GeV and transverse emittances of a few tens of pm.rad, is to be built in Beijing. We have obtained a hybrid 7BA lattice design, with a natural emittance of about 60 pm.rad and a circumference of about 1.3 kilometres, basically satisfying the requirement of on-axis longitudinal injection in HEPS. Nevertheless, it is interesting and necessary to explore the ultimate linear and nonlinear performance of the HEPS hybrid 7BA design. In this paper, we will introduce the multi-objective optimization with a successive and iterative implementation of the MOPSO and MOGA algorithms, and discuss certain relations between the nonlinear dynamics and linear optics of a hybrid MBA lattice. This study can provide reference for other DLSR lattice design and optimizations.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOW025
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WEPOW026	Recent Physical Studies for the HEPS Project	2886
	G. Xu, Z. Duan, Y.Y. Guo, D. Ji, Y. Jiao, X.Y. Li, Y.M. Peng, Q. Qin, J. Qiu, S.K. Tian, J.Q. Wang, N. Wang, Y. Wei, C.H. Yu IHEP, Beijing, People's Republic of China
	The High Energy Photon Source (HEPS), a kilometre- scale storage ring light source, with a beam energy of 5 to 6 GeV and transverse emittances of a few tens of pm.rad, is to be built in Beijing and now is under design. In this paper we reported the progress and status of the physical studies for the HEPS project, covering issues of storage lattice design and optimization, booster design, injection design, collective effects, error study, insertion device effects, longitudinal dynamics, etc.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOW026
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THPMB017	The Errors Study on a Recent Heps Low-Beta Design	3260
	D. Ji, Y. Jiao, G. Xu IHEP, Beijing, People's Republic of China
	The next synchrotron light source High Energy Photon Source is currently studied at Beijing. A nominal design for the HEPS, in a hybrid 7BA lattice and with an emittance of 60 pm.rad in a circumference of 1.3 kilometers, is completed for further study. In this paper, we present some work on error effect based on the nominal lattice design. Topics covered include dynamic aperture and beam parameters affected by magnetic field error, systematic and random multipole errors and misalignment effect.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB017
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THPMB018	Candidate Booster Design for the HEPS Project	3263
	Y.M. Peng, Y.Y. Guo, Y. Jiao, Y. Wei, G. Xu IHEP, Beijing, People's Republic of China
	The High Energy Photon Source (HEPS), with trans-verse emittances of a few tens of pm.rad, is to be built in the suburbs of Beijing, China. The HEPS booster is a 2 Hz electron synchrotron. It accelerates electron bunches from a 300 MeV linac to a final energy of 6 GeV, and then extracts and injects them into the stor-age ring. We have made a candidate booster design, with a circumference of about 432 m and a natural emittance of about 4 nm.rad at 6GeV, which will be located in a separate tunnel. This lattice has a four-fold symmetry. Each super-period is composed of 13 iden-tical cells and two matching cells. The lattice design and optimization and other considerations are present-ed in a detail.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB018
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THPMB019	Comparing the Performance of MOGA and MOPSO in Optimization of the HEPS Performance	3266
	Y. Jiao, G. Xu IHEP, Beijing, People's Republic of China
	The High Energy Photon Source (HEPS), a kilometre- scale diffraction-limited storage ring light source, with a beam energy of 5 to 6 GeV and emittances of a few tens of pm.rad, is to be built in Beijing. A preliminary design with a hybrid 7BA lattice, an emittance of 60 pm.rad and a circumference of about 1.3 kilometers, has been made. Based on this design, we optimized the linear and nonlinear performance of the ring with the MOGA and MOPSO algorithms. From comparison of the performance of these two algorithms, it was found that MOPSO promises higher diversity than MOGA, while MOGA can reach better convergence than MOPSO. To reach a true Pareto front, a successive and iterative implementation of the PSO and MOGA, rather than using either of these two algorithms, is suggested.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB019
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THPOR009	Cepc Partial Double Ring Lattice Design	3785
	F. Su Institute of High Energy Physics (IHEP), People's Republic of China S. Bai, T.J. Bian, Z. Duan, J. Gao, H. Geng, D. Wang, Y. Wang, M. Xiao, G. Xu, Y. Zhang IHEP, Beijing, People's Republic of China
	In this paper, we introduced the layout and lattice design of Circular-Electron-Positron-Collider (CEPC) partial double ring (PDR) scheme. The baseline design of CEPC is a single beam-pipe electron positron collider, which has to adopt pretzel orbit scheme. And it is not suitable to serve as a high luminosity Z factory. If we choose partial double ring scheme, we can get a higher luminosity with lower power and be suitable to serve as a high luminosity Z factory. In this paper, we discussed the details of CEPC partial double ring lattice design and showed the dynamic aperture study and optimization.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR009
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THPOR017	Dynamic Aperture Optimization at CEPC with Pretzel Orbit	3808
	H. Geng, S. Bai, X. Cui, Z. Duan, J. Gao, Y.Y. Guo, Y.M. Peng, Q. Qin, D. Wang, N. Wang, Y. Wang, G. Xu, Y. Yue, Y. Zhang IHEP, Beijing, People's Republic of China W. Chou Fermilab, Batavia, Illinois, USA F. Su Institute of High Energy Physics (IHEP), People's Republic of China
	A preliminary design of the CEPC ring with pretzel orbit will be presented. The ring and pretzel orbit will be designed for 50 bunches, as required in the CEPC Pre-CDR. The linear optics, as well as the non-linear chromaticity compensation with the presence of pretzel orbit will be described. Different phase advance difference between the long and short straight sections, have been tried to optimize the dynamic aperture, the results will be shown in this paper.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR017
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Paper

Title

Page

Power Improvement of Free-Electron Laser Using Transverse-Gradient Undulator with External Focusing

760

G. Zhou, Y. Jiao, G. Xu
IHEP, Beijing, People's Republic of China
J. Wu
SLAC, Menlo Park, California, USA
T. Zhang
SINAP, Shanghai, People's Republic of China

Funding: Supported by National Natural Science Foundation of China (11475202, 11405187) and Youth Innovation Promotion Association of Chinese Academy of Sciences (No. 2015009)
Resent study [Z. Huang et al., Phys. Rev. Lett. 10⁹, 204801 (2012)] shows that the transverse-gradient undu-lator (TGU) together with electron beams with constant dispersion can reduce the sensitivity to energy spread for FEL. In this study, we numerically study FEL using TGU with external focusing. In spite of the dispersion varia-tion, through parameter optimization, FEL using TGU with TGU achieves similar radiation to that without ex-ternal focusing. To achieve a high energy exaction effi-ciency, the initial dispersion should be set with a shift from that corresponding to the resonant condition, and a variation of the transverse gradient in different undulator section is preferred. Other approaches, such as tapering and detuning frequency control, are also discussed to further improve the radiation power and are demonstrated with global parametric optimizations base on simulation.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW020

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TUYA01

BEPCII Performance and Beam Dynamics Studies on Luminosity

1014

C.H. Yu, Z. Duan, S. Gu, Y.Y. Guo, X.Y. Huang, D. Ji, H.F. Ji, Y. Jiao, Zh.C. Liu, Y.M. Peng, Q. Qin, Y.S. Sun, S.K. Tian, J.Q. Wang, N. Wang, X.H. Wang, Y. Wei, X.M. Wen, J. Wu, J. Xing, G. Xu, Y. Yue, C. Zhang, Y. Zhang
IHEP, Beijing, People's Republic of China

The upgrade of the Beijing Electron Positron Collider, BEPCII, is now in a good performance for both high energy physics and synchrotron radiation experiments. The luminosity at the design energy of 1.89 GeV reached the design value 1.0*10³³/cm²/s¹ recently. A lot of work, including accelerator physics study and technical progress, has been done for the luminosity enhancement, not only at the design energy, but all the energy region run for HEP experiments from 1.0 to 2.3 GeV. The performance of BEPCII and the process of luminosity enhancement will be described in detail.

Slides TUYA01 [5.801 MB]

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUYA01

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WEOAA02

On-axis Beam Accumulation Enabled by Phase Adjustment of a Double-frequency RF System for Diffraction-limited Storage Rings

2032

G. Xu, J. Chen, Z. Duan, J. Qiu
IHEP, Beijing, People's Republic of China

Funding: Work supported by NSFC (Y4113G005C)
Future synchrotron light sources aim to achieve ultra- low emittances on both transverse planes, approaching or even reaching the diffraction limit of X-ray photon energies. These diffraction-limited storage rings (DLSRs) feature very strong lattice nonlinearities and thus very small dynamic aperture, which exclude off-axis injection schemes. In this paper, we propose a longitudinal on-axis injection scheme, which is based on a double-frequency RF system and in- dependently adjustment of the RF phase of each cavity to enable RF gymnastics. Such a scheme looks feasible with the state-of-art technology of fast injection kicker. Compari- son with other on-axis injection schemes is also discussed.

Slides WEOAA02 [1.712 MB]

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEOAA02

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WEPOW025

Exploring the Ultimate Linear and Nonlinear Performance of the HEPS hybrid 7BA design

2883

Y. Jiao, G. Xu
IHEP, Beijing, People's Republic of China

The High Energy Photon Source (HEPS), a kilometre- scale diffraction-limited storage ring (DLSR) light source, with a beam energy of 5 to 6 GeV and transverse emittances of a few tens of pm.rad, is to be built in Beijing. We have obtained a hybrid 7BA lattice design, with a natural emittance of about 60 pm.rad and a circumference of about 1.3 kilometres, basically satisfying the requirement of on-axis longitudinal injection in HEPS. Nevertheless, it is interesting and necessary to explore the ultimate linear and nonlinear performance of the HEPS hybrid 7BA design. In this paper, we will introduce the multi-objective optimization with a successive and iterative implementation of the MOPSO and MOGA algorithms, and discuss certain relations between the nonlinear dynamics and linear optics of a hybrid MBA lattice. This study can provide reference for other DLSR lattice design and optimizations.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOW025

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WEPOW026

Recent Physical Studies for the HEPS Project

2886

G. Xu, Z. Duan, Y.Y. Guo, D. Ji, Y. Jiao, X.Y. Li, Y.M. Peng, Q. Qin, J. Qiu, S.K. Tian, J.Q. Wang, N. Wang, Y. Wei, C.H. Yu
IHEP, Beijing, People's Republic of China

The High Energy Photon Source (HEPS), a kilometre- scale storage ring light source, with a beam energy of 5 to 6 GeV and transverse emittances of a few tens of pm.rad, is to be built in Beijing and now is under design. In this paper we reported the progress and status of the physical studies for the HEPS project, covering issues of storage lattice design and optimization, booster design, injection design, collective effects, error study, insertion device effects, longitudinal dynamics, etc.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOW026

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

THPMB017

The Errors Study on a Recent Heps Low-Beta Design

3260

D. Ji, Y. Jiao, G. Xu
IHEP, Beijing, People's Republic of China

The next synchrotron light source High Energy Photon Source is currently studied at Beijing. A nominal design for the HEPS, in a hybrid 7BA lattice and with an emittance of 60 pm.rad in a circumference of 1.3 kilometers, is completed for further study. In this paper, we present some work on error effect based on the nominal lattice design. Topics covered include dynamic aperture and beam parameters affected by magnetic field error, systematic and random multipole errors and misalignment effect.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB017

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THPMB018

Candidate Booster Design for the HEPS Project

3263

Y.M. Peng, Y.Y. Guo, Y. Jiao, Y. Wei, G. Xu
IHEP, Beijing, People's Republic of China

The High Energy Photon Source (HEPS), with trans-verse emittances of a few tens of pm.rad, is to be built in the suburbs of Beijing, China. The HEPS booster is a 2 Hz electron synchrotron. It accelerates electron bunches from a 300 MeV linac to a final energy of 6 GeV, and then extracts and injects them into the stor-age ring. We have made a candidate booster design, with a circumference of about 432 m and a natural emittance of about 4 nm.rad at 6GeV, which will be located in a separate tunnel. This lattice has a four-fold symmetry. Each super-period is composed of 13 iden-tical cells and two matching cells. The lattice design and optimization and other considerations are present-ed in a detail.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB018

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THPMB019

Comparing the Performance of MOGA and MOPSO in Optimization of the HEPS Performance

3266

Y. Jiao, G. Xu
IHEP, Beijing, People's Republic of China

The High Energy Photon Source (HEPS), a kilometre- scale diffraction-limited storage ring light source, with a beam energy of 5 to 6 GeV and emittances of a few tens of pm.rad, is to be built in Beijing. A preliminary design with a hybrid 7BA lattice, an emittance of 60 pm.rad and a circumference of about 1.3 kilometers, has been made. Based on this design, we optimized the linear and nonlinear performance of the ring with the MOGA and MOPSO algorithms. From comparison of the performance of these two algorithms, it was found that MOPSO promises higher diversity than MOGA, while MOGA can reach better convergence than MOPSO. To reach a true Pareto front, a successive and iterative implementation of the PSO and MOGA, rather than using either of these two algorithms, is suggested.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB019

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THPOR009

Cepc Partial Double Ring Lattice Design

3785

F. Su
Institute of High Energy Physics (IHEP), People's Republic of China
S. Bai, T.J. Bian, Z. Duan, J. Gao, H. Geng, D. Wang, Y. Wang, M. Xiao, G. Xu, Y. Zhang
IHEP, Beijing, People's Republic of China

In this paper, we introduced the layout and lattice design of Circular-Electron-Positron-Collider (CEPC) partial double ring (PDR) scheme. The baseline design of CEPC is a single beam-pipe electron positron collider, which has to adopt pretzel orbit scheme. And it is not suitable to serve as a high luminosity Z factory. If we choose partial double ring scheme, we can get a higher luminosity with lower power and be suitable to serve as a high luminosity Z factory. In this paper, we discussed the details of CEPC partial double ring lattice design and showed the dynamic aperture study and optimization.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR009

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THPOR017

Dynamic Aperture Optimization at CEPC with Pretzel Orbit

3808

H. Geng, S. Bai, X. Cui, Z. Duan, J. Gao, Y.Y. Guo, Y.M. Peng, Q. Qin, D. Wang, N. Wang, Y. Wang, G. Xu, Y. Yue, Y. Zhang
IHEP, Beijing, People's Republic of China
W. Chou
Fermilab, Batavia, Illinois, USA
F. Su
Institute of High Energy Physics (IHEP), People's Republic of China

A preliminary design of the CEPC ring with pretzel orbit will be presented. The ring and pretzel orbit will be designed for 50 bunches, as required in the CEPC Pre-CDR. The linear optics, as well as the non-linear chromaticity compensation with the presence of pretzel orbit will be described. Different phase advance difference between the long and short straight sections, have been tried to optimize the dynamic aperture, the results will be shown in this paper.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR017

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