Corkscrew运动影响束流发射度的数值分析  

Simulation of integral emittance growth caused by Corkscrew motion

作　　者：代志勇[1] 黄子平[1] 龙继东[1] 

机构地区：[1]中国工程物理研究院流体物理研究所,四川绵阳621900

出　　处：《强激光与粒子束》2007年第2期288-292,共5页High Power Laser and Particle Beams

基　　金：国防科技基础研究基金资助课题

摘　　要：根据Corkscrew运动的特征,建立了束心Corkscrew运动及其对束流发射度的影响的理论模型,并进行了数值计算,揭示了束心Corkscrew运动造成束流积分发射度增长的一般规律,分析了有关参数对积分发射度的影响。计算结果显示,束心Corkscrew运动是叠加在束心平均偏轴上的一种横向运动,同时也是一种色散效应。虽然束心Corkscrew运动与束心平均偏轴具有很多相同的激励因素,但二者具有截然不同的机理。束流的能散度和初始入射角是Corkscrew运动的两个基本因素,而传输磁场、线圈磁轴倾斜及线圈安装方式对Corkscrew运动的幅度和频率构成较大的影响,并引起束流发射度的增长。只要存在初始入射角、初始入射偏轴或线圈磁轴倾斜中的任何一种因素,就会出现束心偏轴。在数值分析的基础上,针对减小束心Corkscrew运动和束轴的偏心提出了相应的抑制措施。The increase of integral emittance caused by Corkscrew motion in LIA is theoretically analyzed and numerically calculated in the paper. The simulation shows that the Corkscrew of beam centroid is a low frequency motion which overleaps the average eccentricity between centroid of beam and axis of accelerator and a dispersive effect. Although there are many common inspiriting factors, the Corkscrew motion and average eccentricity of beam centroid have absolutely different mechanism. The original inclined incidence and the energy spread of beam are the basic factors of Corkscrew motion. Magnetic field, magnetix axis tilt and assembly method influence obviously the amplitude and frequency of Corkscrew motion, and the growth of integral emittance. On the other hand, the eccentricity of beam centroid will occur without energy spread as there exists original incident angle, original incident eccentricity or magnetic axis tilt of solenoid. Based on the simulation results, some control methods to restrain the Corkscrew motion and the eccentricity are presented.

关 键 词：CORKSCREW运动 积分发射度 数值分析 能散度 磁轴倾斜 

分 类 号：TL501.5[核科学技术—核技术及应用]