BEPCII次谐波聚束系统物理公差要求的研究

 为了进一步提高束流品质并逐步采用双束加速技术, BEPCII直线加速器准备采用带有两个次谐波聚束器的双次谐波聚束系统。目前, 该次谐波聚束系统的物理设计和优化已经基本完成。由于新设计的双次谐波聚束系统很不同于BEPCII现有的聚束系统, 因此, 就要求对聚束系统中存在的各种抖动(jitter)效应重新进行研究。 使用多粒子模拟计算程序PARMELA对电子枪的高压抖动和定时抖动、次谐波聚束器的相位抖动以及功率抖动、聚束器中加速电场相位以及A0加速管(俘获加速节)中加速电场相位的抖动等效应进行了研究, 并最终确定了聚束系统中各部件的物理公差要求。

Tolerance study on BEPCII sub-harmonic bunching system

To improve the beam performance of the two-bunch acceleration (two macro beam pulses in one macro microwave pulse),a new sub-harmonic bunching system has been designed and optimized for BEPCII Linac.Due to the difference between the new bunching system and the present one,the physical tolerances to the key components must be reconsidered.In this paper,the most important jitter effects in the new bunching system are studied systematically,which include the gun timing,high voltage jitters,the phase and power jitters of the two sub-harmonic bunchers and the phase jitters of the 4-cell traveling wave buncher and A0(accelerating section in the bunching system) accelerating tube.A multi-particle simulation program PARMELA is employed,and the physical tolerances of the jitters have been decided.