SRF2017 - List of Authors (Chang, W.)

Paper	Title	Page
MOPB072	The Development of the LLRF Control System for the New High Power Test Stand of Couplers	227
	L. Chen, W. Chang, T.C. Jiang, C.L. Li, Y.M. Li, R.X. Wang, S.H. Zhang IMP/CAS, Lanzhou, People's Republic of China
	RF power conditioning is an effective way to suppress multipacting in fundamental mode power couplers. Room temperature test-stand conditioning is an essential step that can be hardly circumvented before couplers are installed on SC cavities. Based on our original one, a new test-stand has been designed and being assembled at IMP. It can work as a multi-task platform conditioning different couplers, including couplers for HWR010 cavities and HWR015 cavities. It is also featured with the capacity to flexibly change β according to different specifications. A variety of conditioning modes have been incorporated into the LLRF system, including frequency sweeping mode, amplitude sweeping mode, arbitrary-duty-cycle mode and triangle-wave mode. In addition, smartly-conditioning has been achieved because of the accomplishment of smart interlocks and automatic reset in the system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB072
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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
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

The Development of the LLRF Control System for the New High Power Test Stand of Couplers

227

L. Chen, W. Chang, T.C. Jiang, C.L. Li, Y.M. Li, R.X. Wang, S.H. Zhang
IMP/CAS, Lanzhou, People's Republic of China

RF power conditioning is an effective way to suppress multipacting in fundamental mode power couplers. Room temperature test-stand conditioning is an essential step that can be hardly circumvented before couplers are installed on SC cavities. Based on our original one, a new test-stand has been designed and being assembled at IMP. It can work as a multi-task platform conditioning different couplers, including couplers for HWR010 cavities and HWR015 cavities. It is also featured with the capacity to flexibly change β according to different specifications. A variety of conditioning modes have been incorporated into the LLRF system, including frequency sweeping mode, amplitude sweeping mode, arbitrary-duty-cycle mode and triangle-wave mode. In addition, smartly-conditioning has been achieved because of the accomplishment of smart interlocks and automatic reset in the system.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB072

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

Export •

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