IPAC2016 - List of Authors (Dai, J.P.)

Paper	Title	Page
MOPMB032	A New Fault Recovery Mechanism for Superconducting Cavity Failure in C-ADS	158
	Z. Xue, J.P. Dai, C. Meng IHEP, Beijing, People's Republic of China
	For proton linear accelerators used in applications such as C-ADS, due to the nature of the operation, it is essential to have beam failures at the rate several orders of magnitude lower than usual performance of similar accelerators. A fault-tolerant mechanism should be mandatorily imposed in order to maintain short recovery time, high uptime and extremely low frequency of beam loss. This paper proposes an innovative and challenging way for compensation and rematch of cavity failure using fast electronic devices and Field Programmable Gate Array (FPGA) instead of embedded computers to complete the computation of beam dynamics. Due to the high arithmetic-computing-speed, good portability and repeatability, it is possible to realize calculation and re-adjustment online. In order to achieve the goal of instantaneous compensation and rematch, an advanced hardware design methodology including high-level synthesis and an improved genetic algorithm will be used.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB032
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WEPMB029	Research of Nitrogen Doping at IHEP	2186
	P. Sha Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China J.P. Dai IHEP, Beijing, People's Republic of China F. Jiao PKU, Beijing, People's Republic of China
	Funding: Work funded by National Natural Science Foundation of China, Grant No. 11505197 Recently, nitrogen doping (N-doping) technology has been proved to increase Q0 of superconducting cavity obviously, which lowers the BCS surface resistance. After N-doping, Q0 of 9-cell 1.3 GHz cavity can be increased to 310¹⁰ at Eacc = 16 MV/m, while 1.51010 without N-doping [1]. Since 2013, there have been over 60 cavities nitrogen doped at FNAL, JLAB and Cornell. The Circular Electron Collider (CEPC) has been proposed by IHEP in China, while requests Q0=4e10@Eacc=15.5 MV/m for 650 MHz cavity. It's hard to achieve without N-doping. So research of N-doping was begun in cooperation with Peking University in early 2015. Experiments of niobium samples have showed that nitrogen concentration at niobium surface increased a lot after N-doping. After then, several single-cell 1.3 GHz cavities completed vertical tests, but there're no successful test results of Q0 increasing, yet.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB029
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WEPMB030	Design Study of a Compact Deflecting Cavity at IHEP	2188
	J.P. Dai, B. Ni, J.Y. Zhai, J.R. Zhang IHEP, Beijing, People's Republic of China
	For the XFEL project proposed by IHEP, a sophisticated beam spreader is required to separate a single beam into multiple beams. One of the deflecting cavities used in the spreader has been investigated and optimized. It is a 325 MHz, compact RF-dipole superconducting cavity, with the transverse R/Q of 2900Ω, geometrical factor G of 88.5 Ω, and the Helium pressure sensitivity df/dp of 3.4 Hz/mbar. At the nominal deflecting voltage of 7MV, the peak electric field Epeak is 41 MV/m and peak magnetic field Bpeak is 48 mT. This paper will present the detailed RF and mechanical designs.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB030
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WEPMB031	Post Processing of Spoke Type Superconducting Cavities at Institute of High Energy Physics	2191
	J. Dai, J.P. Dai, F.S. He, X. Huang, L.H. Li, Z.Q. Li, H.Y. Lin, Z.C. Liu, B. Ni, W.M. Pan, P. Sha, G.W. Wang, Q.Y. Wang, Z. Xue, X.Y. Zhang, G.Y. Zhao IHEP, Beijing, People's Republic of China
	Funding: Work supported by Chinese Academy of Science strategic Priority Research Program-Future Advanced Nuclear Fission Energy. After upgrading the post-processing system, several superconducting cavities were RF tested at Institute of High Energy Physics (IHEP) in China recently. The test results of 14 spoke 012 cavities and 6 spoke 021 cavities which used at China ADS injector I and linac all exceeds our design objective. Moreover, a spoke 040, a 650MHz elliptical cavity and a 325MHz HWR cavity are also vertical tested and the test results are all significantly surpass our design value. The post processing of these cavities including Buffered Chemical Polishing (BCP), high temperature heat treatment and High Pressure water Rinsing (HPR) is presented here. daijin@pku.edu.cn
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB031
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Paper

Title

Page

A New Fault Recovery Mechanism for Superconducting Cavity Failure in C-ADS

158

Z. Xue, J.P. Dai, C. Meng
IHEP, Beijing, People's Republic of China

For proton linear accelerators used in applications such as C-ADS, due to the nature of the operation, it is essential to have beam failures at the rate several orders of magnitude lower than usual performance of similar accelerators. A fault-tolerant mechanism should be mandatorily imposed in order to maintain short recovery time, high uptime and extremely low frequency of beam loss. This paper proposes an innovative and challenging way for compensation and rematch of cavity failure using fast electronic devices and Field Programmable Gate Array (FPGA) instead of embedded computers to complete the computation of beam dynamics. Due to the high arithmetic-computing-speed, good portability and repeatability, it is possible to realize calculation and re-adjustment online. In order to achieve the goal of instantaneous compensation and rematch, an advanced hardware design methodology including high-level synthesis and an improved genetic algorithm will be used.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB032

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WEPMB029

Research of Nitrogen Doping at IHEP

2186

P. Sha
Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China
J.P. Dai
IHEP, Beijing, People's Republic of China
F. Jiao
PKU, Beijing, People's Republic of China

Funding: Work funded by National Natural Science Foundation of China, Grant No. 11505197
Recently, nitrogen doping (N-doping) technology has been proved to increase Q0 of superconducting cavity obviously, which lowers the BCS surface resistance. After N-doping, Q0 of 9-cell 1.3 GHz cavity can be increased to 3*10¹⁰ at Eacc = 16 MV/m, while 1.5*1010 without N-doping [1]. Since 2013, there have been over 60 cavities nitrogen doped at FNAL, JLAB and Cornell. The Circular Electron Collider (CEPC) has been proposed by IHEP in China, while requests Q0=4e10@Eacc=15.5 MV/m for 650 MHz cavity. It's hard to achieve without N-doping. So research of N-doping was begun in cooperation with Peking University in early 2015. Experiments of niobium samples have showed that nitrogen concentration at niobium surface increased a lot after N-doping. After then, several single-cell 1.3 GHz cavities completed vertical tests, but there're no successful test results of Q0 increasing, yet.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB029

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

WEPMB030

Design Study of a Compact Deflecting Cavity at IHEP

2188

J.P. Dai, B. Ni, J.Y. Zhai, J.R. Zhang
IHEP, Beijing, People's Republic of China

For the XFEL project proposed by IHEP, a sophisticated beam spreader is required to separate a single beam into multiple beams. One of the deflecting cavities used in the spreader has been investigated and optimized. It is a 325 MHz, compact RF-dipole superconducting cavity, with the transverse R/Q of 2900Ω, geometrical factor G of 88.5 Ω, and the Helium pressure sensitivity df/dp of 3.4 Hz/mbar. At the nominal deflecting voltage of 7MV, the peak electric field Epeak is 41 MV/m and peak magnetic field Bpeak is 48 mT. This paper will present the detailed RF and mechanical designs.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB030

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

WEPMB031

Post Processing of Spoke Type Superconducting Cavities at Institute of High Energy Physics

2191

J. Dai, J.P. Dai, F.S. He, X. Huang, L.H. Li, Z.Q. Li, H.Y. Lin, Z.C. Liu, B. Ni, W.M. Pan, P. Sha, G.W. Wang, Q.Y. Wang, Z. Xue, X.Y. Zhang, G.Y. Zhao
IHEP, Beijing, People's Republic of China

Funding: Work supported by Chinese Academy of Science strategic Priority Research Program-Future Advanced Nuclear Fission Energy.
After upgrading the post-processing system, several superconducting cavities were RF tested at Institute of High Energy Physics (IHEP) in China recently. The test results of 14 spoke 012 cavities and 6 spoke 021 cavities which used at China ADS injector I and linac all exceeds our design objective. Moreover, a spoke 040, a 650MHz elliptical cavity and a 325MHz HWR cavity are also vertical tested and the test results are all significantly surpass our design value. The post processing of these cavities including Buffered Chemical Polishing (BCP), high temperature heat treatment and High Pressure water Rinsing (HPR) is presented here.
daijin@pku.edu.cn

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB031

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