上海光源储存环横向反馈系统模拟计算.pdfVIP

1 31 ò 1 10 ? 2007 c 10  p U ? n ? ? ? n HIGH ENERGY PHYSICS AND NUCLEAR PHYSICS Vol. 31, No. 10 Oct., 2007 Simulation of a Transverse Feedback System for the SSRF Storage Ring * JIANG Bo-Cheng1,2 LIU Gui-Min1 ZHAO Zhen-Tang1;1) 1 (Shanghai Institute of Applied Physics, CAS, Shanghai 201800, China) 2 (Graduate University of Chinese Academy of Sciences, Beijing 100049, China) Abstract Resistive wall instability is a serious problem in many light sources. An active transverse feedback system (TFS) is required to operate the machine in a good condition when beam current is high. In order to investigate beam dynamics with TFS turned on, we developed a TFS simulation program. The feedback effectiveness for the Shanghai Synchrotron Radiation Facility (SSRF) storage ring is simulated under various conditions such as closed orbit distortion included, beam position monitor reading errors added, and finite- duration impulse-response filter strategy changed. Key words SSRF, feedback, simulation, accelerator toolbox (AT) 1 Introduction Shanghai Synchrotron Radiation Facility (SSRF) is a 3rd generation synchrotron light source based on a 3.5GeV and 300mA storage ring. The ring vacuum chamber with octagonal (68mm×35mm) cross section is made of stainless steel. When the SSRF storage ring is filled uniformly with 720 bunches, its resistive wall instability threshold in the vertical plane is only about 70mA when chromaticity is zero. Some of the most dangerous instability modes are listed in Ta- ble 1. Although, increasing the chromaticity could raise the transverse instability threshold [1] , it will strongly impact the injection efficiency [2] , reduce the dynamic apertures and the beam lifetime [3] . Further- more, narrow-gap insertion devices would be installed in the ring which will make the instability even severe. Table 1. Growth time of resistive-wall instability. mode number 708 707 706 705 704 growth time/ms 1.68 2.65 3.34 3.92 4.42 So the implementation of a transverse f