Analytic modeling of instabilities driven by higher-order modes in the HLS Ⅱ RF system with a higher-harmonic cavity  

作　　者：赵宇宁 李为民 吴丛凤 王琳 

机构地区：[1]National Synchrotron Radiation Laboratory, University of Science and Technology of China

出　　处：《Chinese Physics C》2013年第8期73-75,共3页中国物理C（英文版）

基　　金：Supported by National Natural Science Foundation of China (10979045, 11175180, 11175182)

摘　　要：The utility of a passive fourth-harmonic cavity plays a key role in suppressing longitudinal beam insta- bilities in the electron storage ring and lengthens the bunch by a factor of 2.6 for the phase I[ project of the Hefei Light Source （HLS II ）. Meanwhile, instabilities driven by higher-order modes （HOM） may limit the performance of the higher-harmonic cavity. In this paper, the parasitic coupled-bunch instability, which is driven by narrow band parasitic modes, and the microwave instability, which is driven by broadband HOM, are both modeled analytically. The analytic modeling results are in good agreement with those of our previous simulation study and indicate that the passive fourth-harmonic cavity suppresses parasitic coupled-bunch instabilities and microwave instability. The modeling suggests that a fourth-harmonic cavity may be successfully used at the HLS II.The utility of a passive fourth-harmonic cavity plays a key role in suppressing longitudinal beam insta- bilities in the electron storage ring and lengthens the bunch by a factor of 2.6 for the phase I[ project of the Hefei Light Source （HLS II ）. Meanwhile, instabilities driven by higher-order modes （HOM） may limit the performance of the higher-harmonic cavity. In this paper, the parasitic coupled-bunch instability, which is driven by narrow band parasitic modes, and the microwave instability, which is driven by broadband HOM, are both modeled analytically. The analytic modeling results are in good agreement with those of our previous simulation study and indicate that the passive fourth-harmonic cavity suppresses parasitic coupled-bunch instabilities and microwave instability. The modeling suggests that a fourth-harmonic cavity may be successfully used at the HLS II.

关 键 词：parasitic coupled-bunch instability microwave instability higher-harmonic cavity analytic modeling higher-order mode 

分 类 号：TL503[核科学技术—核技术及应用]