In situ mitigation strategies for field emission-induced cavity faults using low-level radiofrequency system  

作　　者：Feng Qiu Yuan He An-Dong Wu Zhen-Long Zhu Guo-Dong Jiang Tian-Cai Jiang Zheng Gao Qi Chen Zong-Heng Xue Jin-Ying Ma Cheng-Ye Xu Zi-Qin Yang Gui-Rong Huang 

机构地区：[1]Institute of Modern Physics,Chinese Academy of Sciences,Lanzhou 730000,China [2]School of Nuclear Science and Technology,University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Nuclear Science and Techniques》2022年第11期46-60,共15页核技术（英文）

基　　金：supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB34010000);Large Research Infrastructures China initiative Accelerator Driven System(2017-000052-75-01-000590);National Natural Science Foundation of China(No.12175283);Studies of intelligent LLRF control algorithms for SC RF cavities(No.E129851YR0).

摘　　要：In the Chinese ADS front-end demo superconducting radiofrequency linac(CAFe)at the Institute of Modern Physics,a burst-noise signal-triggered cavity fault frequently appears during beam commissioning.These events are characterized by a rapid burst noise in the cavity pick-up,which may lead to an unexpected low-level radiofrequency(LLRF)response that eventually causes a cavity fault.To eliminate the undesirable reaction of the LLRF control loop,we propose a method that uses a burstnoise detection and processing algorithm integrated into the LLRF feedback controller.This algorithm can prevent undesired regulations in LLRF systems.Data analysis revealed that some burst-noise events did not exhibit measurable energy loss.In contrast,the other events were accompanied by a rapid loss of cavity stored energy and exhibited similarities to the‘‘E-quench’’phenomena reported in other laboratories.A particle-in-cell simulation indicated that the suspected E-quench phenomenon may be related to a plasma formation process inside the cavity.Fortunately,the LLRF algorithm is robust to the two different types of burst-noise events and can significantly mitigate the corresponding cavity faults in CAFe beam commissioning.

关 键 词：Field emission FLASHOVER E-quench Superconducting LLRF CAFE Plasma formation 

分 类 号：TL53[核科学技术—核技术及应用]