SRF2017 - List of Authors (Wu, A.D.)

Paper	Title	Page
MOPB007	Design of the Superconducting Quarter Wave Resonators for HIAF	59
	C. Zhang, L. Chen, Q.W. Chu, H. Guo, Y. He, S.C. Huang, Y.L. Huang, T.C. Jiang, L. Li, Y.M. Li, F. Pan, T. Tan, R.X. Wang, A.D. Wu, Q.J. Wu, P.R. Xiong, W.M. Yue, S.H. Zhang, S.X. Zhang IMP/CAS, Lanzhou, People's Republic of China
	A heavy ion accelerator facility (HIAF) is under development in the Institute of Modern Physics. For the low energy superconducting accelerating section, two types of quarter wave resonators with frequency of 81.25 MHz and β of 0.05 and 0.10 have been proposed. The electro-magnetic design has been optimized in order to reach the high accelerating voltage, and the optimization also included the drift tube face tilting to compensate for the beam steering caused by the asymmetry in the quarter wave resonator geometry.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB007
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MOPB074	Analysis of Higher Order Modes of the Superconducting Cavities for the China-ADS Injector-II in IMP	231
	C. Zhang, L. Chen, Y. He, S.C. Huang, Y.L. Huang, T.C. Jiang, Y.M. Li, F. Pan, R.X. Wang, A.D. Wu, Q.J. Wu, W.M. Yue, S.H. Zhang, S.X. Zhang IMP/CAS, Lanzhou, People's Republic of China
	Funding: funded by Natural Science Foundation of China， No.11505253 The influence of the higher order modes on the beam dynamics and the cryogenic losses has been studied for the superconducting section of the CIADS project in this paper. In addition, the necessity of HOM dampers in the Superconducting (SC) cavities is discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB074
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TUPB086	Study on Local Chemical Treatment for Recovery From Surface Oxidation by HPR Process on SRF Cavities	592
	H. Guo, Y. He, Y.M. Li, T. Tan, A.D. Wu, P.R. Xiong, Z.M. You, W.M. Yue, S.H. Zhang IMP/CAS, Lanzhou, People's Republic of China
	High pressure rinsing (HPR) with ultra-pure water (UPW) is the last step which is commonly used for SRF cavities cleaning. The serious surface damage will be caused due to the failure of the distance control between the jet and cavity surface or the breakdown of the jet rotation. The surface of taper HWR cavities which are used for CIADS project was damaged in HPR process. Two methods were used for surface recovery and the result will be presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB086
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TUPB087	Low Temperature and Low Pressure Plasma for the HWR Superconducting Cavity In-situ Cleaning	595
	A.D. Wu, W. Chang, H. Guo, Y. He, C.L. Li, Y.M. Li, P.R. Xiong, L. Yang, W.M. Yue, S.H. Zhang, H.W. Zhao IMP/CAS, Lanzhou, People's Republic of China F. Gou Sichuan University, Chengdu, People's Republic of China
	The glow discharge for low temperature and low pressures plasma were utilized for the half-wave resonator (HWR) superconducting cavity in-situ cleaning. The plasma was on ignition of the Argon/Oxygen mixture atmosphere, which was under the low pressure of 0.5 to 5.0 Pascal. Driven by the RF power with the frequency of the cavity fundamental mode, the plasma showed the typical characteristic of the typical RF glow discharge, which the temperature of the electrons about 1eV that diagnosed by the optical emission spectrum. The experimental parameters for the discharge were optimized to obtain the uniform plasma distribution on the HWR cavity, including the RF power, the atmospheric pressure and the oxygen proportion. At last, the vertical cryogenic test was completed to investigate the impact of active oxygen plasma cleaning on the HWR cavity performance recovery, which contaminated by hydrocarbons. The test proves that the glow plasma clean can relieve the x-ray radiation which caused by the field electron emission effect.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB087
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THPB024	Investigation on Depth Profiling of Niobium Surface Composition and Work Function of SRF Cavities	779
	A.D. Wu, L. Chen, Q.W. Chu, H. Guo, Y. He, Y.M. Li, F. Pan, L. Yang, S.H. Zhang, H.W. Zhao IMP/CAS, Lanzhou, People's Republic of China
	The niobium samples were prepared by different surface treatments that commonly applied for the superconducting RF cavities preparation, as the following of electrochemical polishing, the buffered chemical polishing and high temperature annealing. In order to understand the property of niobium surface, especially the relationship between the composition and the work function value, the X-ray and ultraviolet photoelectron spectra depth profiling has been studied. The intensity photoelectrons signals of O1s, C1s and the Nb3d were identified for composition of the niobium oxide and the hydrocarbon contamination. And the work function of sample surface was measured via the means of the ultraviolet photoelectron spectra band width. To make a depth profiling, the sputtering of Argon ions was used to remove surface material gradually under by control the sputtering times. The results shown that the value of work function strongly depends on the chemical composition.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB024
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Paper

Title

Page

Design of the Superconducting Quarter Wave Resonators for HIAF

59

C. Zhang, L. Chen, Q.W. Chu, H. Guo, Y. He, S.C. Huang, Y.L. Huang, T.C. Jiang, L. Li, Y.M. Li, F. Pan, T. Tan, R.X. Wang, A.D. Wu, Q.J. Wu, P.R. Xiong, W.M. Yue, S.H. Zhang, S.X. Zhang
IMP/CAS, Lanzhou, People's Republic of China

A heavy ion accelerator facility (HIAF) is under development in the Institute of Modern Physics. For the low energy superconducting accelerating section, two types of quarter wave resonators with frequency of 81.25 MHz and β of 0.05 and 0.10 have been proposed. The electro-magnetic design has been optimized in order to reach the high accelerating voltage, and the optimization also included the drift tube face tilting to compensate for the beam steering caused by the asymmetry in the quarter wave resonator geometry.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB007

Export •

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

MOPB074

Analysis of Higher Order Modes of the Superconducting Cavities for the China-ADS Injector-II in IMP

231

C. Zhang, L. Chen, Y. He, S.C. Huang, Y.L. Huang, T.C. Jiang, Y.M. Li, F. Pan, R.X. Wang, A.D. Wu, Q.J. Wu, W.M. Yue, S.H. Zhang, S.X. Zhang
IMP/CAS, Lanzhou, People's Republic of China

Funding: funded by Natural Science Foundation of China， No.11505253
The influence of the higher order modes on the beam dynamics and the cryogenic losses has been studied for the superconducting section of the CIADS project in this paper. In addition, the necessity of HOM dampers in the Superconducting (SC) cavities is discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB074

Export •

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

TUPB086

Study on Local Chemical Treatment for Recovery From Surface Oxidation by HPR Process on SRF Cavities

592

H. Guo, Y. He, Y.M. Li, T. Tan, A.D. Wu, P.R. Xiong, Z.M. You, W.M. Yue, S.H. Zhang
IMP/CAS, Lanzhou, People's Republic of China

High pressure rinsing (HPR) with ultra-pure water (UPW) is the last step which is commonly used for SRF cavities cleaning. The serious surface damage will be caused due to the failure of the distance control between the jet and cavity surface or the breakdown of the jet rotation. The surface of taper HWR cavities which are used for CIADS project was damaged in HPR process. Two methods were used for surface recovery and the result will be presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB086

Export •

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

TUPB087

Low Temperature and Low Pressure Plasma for the HWR Superconducting Cavity In-situ Cleaning

595

A.D. Wu, W. Chang, H. Guo, Y. He, C.L. Li, Y.M. Li, P.R. Xiong, L. Yang, W.M. Yue, S.H. Zhang, H.W. Zhao
IMP/CAS, Lanzhou, People's Republic of China
F. Gou
Sichuan University, Chengdu, People's Republic of China

The glow discharge for low temperature and low pressures plasma were utilized for the half-wave resonator (HWR) superconducting cavity in-situ cleaning. The plasma was on ignition of the Argon/Oxygen mixture atmosphere, which was under the low pressure of 0.5 to 5.0 Pascal. Driven by the RF power with the frequency of the cavity fundamental mode, the plasma showed the typical characteristic of the typical RF glow discharge, which the temperature of the electrons about 1eV that diagnosed by the optical emission spectrum. The experimental parameters for the discharge were optimized to obtain the uniform plasma distribution on the HWR cavity, including the RF power, the atmospheric pressure and the oxygen proportion. At last, the vertical cryogenic test was completed to investigate the impact of active oxygen plasma cleaning on the HWR cavity performance recovery, which contaminated by hydrocarbons. The test proves that the glow plasma clean can relieve the x-ray radiation which caused by the field electron emission effect.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB087

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

THPB024

Investigation on Depth Profiling of Niobium Surface Composition and Work Function of SRF Cavities

779

A.D. Wu, L. Chen, Q.W. Chu, H. Guo, Y. He, Y.M. Li, F. Pan, L. Yang, S.H. Zhang, H.W. Zhao
IMP/CAS, Lanzhou, People's Republic of China

The niobium samples were prepared by different surface treatments that commonly applied for the superconducting RF cavities preparation, as the following of electrochemical polishing, the buffered chemical polishing and high temperature annealing. In order to understand the property of niobium surface, especially the relationship between the composition and the work function value, the X-ray and ultraviolet photoelectron spectra depth profiling has been studied. The intensity photoelectrons signals of O1s, C1s and the Nb3d were identified for composition of the niobium oxide and the hydrocarbon contamination. And the work function of sample surface was measured via the means of the ultraviolet photoelectron spectra band width. To make a depth profiling, the sputtering of Argon ions was used to remove surface material gradually under by control the sputtering times. The results shown that the value of work function strongly depends on the chemical composition.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-THPB024

Export •

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