Author: Liu, H.
Paper Title Page
MOPB13 Active Magnetic Field Compensation System for SRF Cavities 101
 
  • L.H. Ding
    Laboratory GREYC, Caen, France
  • J. Liang, H. Liu, Z.P. Xie
    Hohai University, Nanjing, People’s Republic of China
  • Z.P. Xie
    IMP/CAS, Lanzhou, People’s Republic of China
  
  Abstract: Superconducting Radio Frequency (SRF) cavities are becoming popular in modern particle accelerators. When the SRF cavity is transitioning from the non-conducting to the Superconducting state at the critical temperature (Tc), the ambient magnetic field can be trapped. This trapped flux may lead to an increase in the surface resistance of the cavity wall, which can reduce the Q-factor and efficiency of the cavity. In order to increase the Q-factor, it is important to lower the surface resistance by reducing the amount of magnetic flux trapped in the cavity wall to sub 10mG range during the Tc transition. In this paper, we present a 3-axis automatic active magnetic field compensation system that is capable of reducing the earth magnetic field and any local disturbance field. Design techniques are described to enhance the system stability while utilizing the flexibility of embedded electronics. This paper describes the system implementation and concludes with initial results of tests. Experimental results demonstrate that the proposed magnetic field compensation system can reduce the earth magnetic field to around 2.5 mG even without shielding.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-MOPB13  
About • paper received ※ 05 September 2018       paper accepted ※ 12 September 2018       issue date ※ 29 January 2019  
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TUPA08 Arc Discharge Detectors for the CiADS Superconducting RF Cavities 228
 
  • Z.P. Xie, Y.K. Ding, J. Liang, H. Liu
    Hohai University, Nanjing, People’s Republic of China
  • Y. He, Y.M. Li
    IMP/CAS, Lanzhou, People’s Republic of China
  
  Funding: Work supported by the National Natural Science Foundation of China (Grant No.11505255, No.91026001) and the Fundamental Research Funds for the Chinese Central Universities(2015B29714)
Arc discharge due to the electron emission is one of the key issues in the CW superconducting RF(SRF) for the CiADS particle accelerator. Arc discharges can deteriorate the SRF cavities and damage the facility. Monitoring arc discharges is important for the purpose of machine protection. In this paper, an arc discharge detector has been designed to provide fast response upon events of arc discharge using open-source hardware and LabVIEW software. Electronic design techniques are described to enhance the system stability while utilizing the flexibility of embedded electronics. The proposed detector system gives about 700 ns of response time and it employs a LabVIEW based graphic user interface. The system has the capability of detecting the instantaneous arc discharge events in real time. Timestamps of the event will be recorded to assist beam diagnostics. This paper describes the hardware/software implementation and concludes with initial results of tests at CiADS. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-TUPA08  
About • paper received ※ 04 September 2018       paper accepted ※ 11 September 2018       issue date ※ 29 January 2019  
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