中国散裂中子源快循环同步加速器中色品校正及六极磁铁非线性效应(英文)

Chromatic correction for CSNS/RCS and nonlinear effects of chromaticity sextupoles

中国散裂中子源(CSNS)快循环同步加速器(RCS)把能量为80MeV的束流储存并加速到1.6GeV然后引出到靶站。为了减少RCS中的束流损失,有必要对RCS做色品校正,并减小动量偏移对束流光学的影响。尝试了多种色品校正方案并对不同色品校正方案做了比较。用三维跟踪程序SIMPSONS研究了色品校正六极铁与空间电荷效应对束流的影响。色品校正六极铁可以有效减小色品引起的频散,但是由于六极铁为非线性元件,导致不同振幅的粒子间有一定频散。模拟发现同时存在空间电荷效应和色品校正六极铁时,会有少量的束流损失。

The rapid cycling synchrotron （RCS） of the China Spallation Neutron Source （CSNS） accumu- lates an 80 MeV injected beam, and accelerates 1.56× 1013 particles to the design energy of 1.6 GeV, and ex- tracts the high energy beam to the target. In order to keep low beam losses in the ring, it is necessary to control the chromaticity and to minimize the dependence of the optical properties on beam momentum spread. Three chromatic correction schemes are proposed and compared for CSNS/RCS in this paper. The combined effects of sextupole field and space charge are investigated by using the code SIMPSONS. The tune spread produced by chromaticity carl be apparently reduced by using chromaticity sextupoles. However, the chromaticity sextupoles are non-linear elements, and can introduce an amplitude-dependent tuneshift. The combined effects of sextupole field and space charge can induce some beam loss.