Author: Zhang, S.X.
Paper Title Page
MOFAB4
Overview and SRF Requirements of the CiADS Project  
 
  • Y. He, Q. Chen, Z. Gao, H. Guo, G. Huang, Y.L. Huang, T.C. Jiang, C.L. Li, S.H. Liu, T. Tan, Y.Q. Wan, F.F. Wang, J.Q. Wu, W.M. Yue, B. Zhang, J.H. Zhang, S.H. Zhang, S.X. Zhang
    IMP/CAS, Lanzhou, People’s Republic of China
  • J.P. Dai, F.S. He, Z.Q. Li, W.M. Pan
    IHEP, Beijing, People’s Republic of China
  • T.C. Jiang
    University of Chinese Academy of Sciences, Beijing, People’s Republic of China
 
  Chinese initiative Accelerator Driven System started constructing in 2018. It consists a superconducting linac with 500 MeV and 5 mA; an LEB coolant fast reactor with 7.5 MW. The first beam coupling with reactor will be in 2024. The sc linac employed 5 families of superconducting resonators, two types of HWRs (β=0.1 and β=0.19), one type of double spokes (β=0.42) and two types of ellipticals (β=0.62 and β=0.82). The whole system will operate in 2 K. A space has been reserved for future upgrading to 1 GeV. As a demo of front-end of ADS, the CAFe (China ADS Front-end demo linac) has been developed and commissioned to verify the SRF techniques, high power CW beam and RAMI. 45 kW proton beam has been delivered to the dump and lasted more than 100 hours at the beginning of 2019. According to the operation experience, the challenge is the stability and performance of cavities under the heavy beam loading, some phenomenas have been observed. Up to now, the design of bulk Nb cavities have been finished and the prototype fabrication is on going. The techniques of Nb/Cu cavity and Nb3Sn are also developed in IMP for the future project of ADS.  
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MOP003 Development of Nb3Sn Cavity Coating at IMP 21
 
  • Z.Q. Yang, H. Guo, Y. He, C.L. Li, Z.Q. Lin, M. Lu, T. Tan, P.R. Xiong, S.H. Zhang, S.X. Zhang
    IMP/CAS, Lanzhou, People’s Republic of China
 
  The A15 superconductor Nb3Sn is one of the most promising alternative materials to standard niobium for SRF applications. In this paper, we report our progress in the development of Nb3Sn cavity coating by vapor diffusion method at IMP. The evolutionary process of nucleation was analyzed. Influence of SnCl2 partial pressure inhomogeneity was studied. Less-nuclear zones were found on the surfaces of nucleation samples. The Nb3Sn film structure and composition were investigated and analyzed. In light of knowledge obtained above, the coating process was optimized. Finally, both 1.3 GHz and 650 MHz single cell cavities were coated and vertically tested both at 4 K and 2 K. Effect of low temperature baking (1000°C for 48 hs) on the RF performance of Nb3Sn cavity was studied. After baking, the Q drop in the low field region was eliminated and the Q in the intermediate field region was increased 8 times. The Q was 10 times larger than that of the Nb cavity at 4.2 K even in the case of the ambient field larger than 20 mGs. This study shows that the low temperature baking is an effective enrichment to the post treatment of the Nb3Sn cavity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP003  
About • paper received ※ 23 June 2019       paper accepted ※ 03 July 2019       issue date ※ 14 August 2019  
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MOP073 The Study of High Power Couplers for CIADS 241
SUSP007   use link to see paper's listing under its alternate paper code  
 
  • Z.Q. Lin, Y. He, S.C. Huang, Y.L. Huang, T.C. Jiang, C.L. Li, Y.M. Li, M. Lu, F. Pan, T. Tan, R.X. Wang, Z. Xue, Z.Q. Yang, S.X. Zhang
    IMP/CAS, Lanzhou, People’s Republic of China
 
  High power couplers with high operation reliability are needed for the superconducting cavities used in the Linac of CiADS project at IMP. This paper will report two works on high power coupler. The DC bias structure of the coupler was optimized to suppress the multipacting effect, where the series resistors were introduced to the wire of the DC bias to reduce the field propagating along the DC bias’s wire. For the purpose of significantly decreasing the power needed to condition the coupler, we designed a new RF conditioning scheme, in which the coupler served as a standing wave resonator, and the positions of the crests and troughs of the wave were tunable. The details of the design mentioned above will be depicted.  
poster icon Poster MOP073 [14.677 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP073  
About • paper received ※ 25 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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FRCAB6 The Effect of Helium Processing and Plasma Cleaning for Low Beta HWR Cavity 1228
THP065   use link to see paper's listing under its alternate paper code  
 
  • S.C. Huang, Q.W. Chu, Y. He, C.L. Li, A.D. Wu, S.X. Zhang
    IMP/CAS, Lanzhou, People’s Republic of China
 
  The commissioning of the 25 MeV high power and high intensity proton Linac demo for CiADS showed that the performance of the SRF cavities was mainly limited by field emission inside the cavities. Therefore, the techniques of helium processing and reactive oxygen plasma cleaning have been developed to mitigate field emission issues. We performed an experiment with a low beta HWR cavity exposed to air directly and processed by helium and reactive oxygen. In this paper, the details of the experiment will be described, the efficiency of helium processing and plasma cleaning will be compared and discussed  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-FRCAB6  
About • paper received ※ 23 June 2019       paper accepted ※ 01 July 2019       issue date ※ 14 August 2019  
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