Improvement of Linear Accelerator Numerical Simulation Algorithm Based on Symmetry Principle  

基于对称性原理优化直线加速器数值模拟算法

作　　者：JIN Chao YANG Lijuan ZHAO Xiaoying QI Xin WANG Zhijun HE Yuan 金超;杨丽娟;赵晓莹;齐新;王志军;何源(中国科学院近代物理研究所,兰州730000;中国科学院大学核科学与技术学院,北京100049;先进能源科学与技术广东省实验室,广东惠州516000)

机构地区：[1]Institute of Modern Physics,Chinese Academy of Sciences,Lanzhou 730000,China [2]School of Nuclear Science and Technology,University of Chinese Academy of Sciences,Beijing 100049,China [3]Advanced Energy Science and Technology Guangdong Laboratory,Huizhou 516000,Guangdong,China

出　　处：《原子核物理评论》2024年第4期967-974,共8页Nuclear Physics Review

基　　金：国家自然科学基金资助项目(11775282)。

摘　　要：In the study of beam dynamics of high intensity linear accelerators,full 3D multiparticle simulations are needed due to numerous nonlinear effects caused by the strong space-charge effects between charged particles.However,the use of multiparticle simulations is limited by the speed of the Particle-in-cell(PIC)algorithm.In this work,we modify the PIC algorithm by using the symmetry of beam,the solution procedure is divided into two steps,one is the solution of the symmetric field and the other is the addition of the asymmetric field components.Due to the full use of symmetry,our modified algorithm can significantly improve the computational speed of multiparticle simulations.Results show that the modified algorithm accelerates the process of solving space-charge field by a factor of 4,thus increases the speed of the entire multiparticle simulation by a factor of 1.7,while ensures the accuracy of the simulation.Although our algorithm is modified for linear accelerator,considering that the algorithm is an improvement based on symmetry,it can still speed up the simulation for any accelerator with symmetry.在研究强流直线加速器的束流动力学时,由于带电粒子间强烈的空间电荷效应引起了大量非线性效应,需要进行三维的多粒子模拟。然而,多粒子模拟的使用受限于粒子云网格算法(Particle-in-cell,PIC)的计算速度。本工作利用束流的对称性对PIC算法进行了改进,将空间电荷场的求解过程分为两步,首先是求解空间电荷场的对称分量,随后叠加不对称的场分量。由于充分利用了对称性,改进后的算法可以显著提高多粒子模拟的速度。结果表明,改进后的算法在保证模拟精度的前提下,将空间电荷场的求解过程加快了4倍,使整个多粒子模拟的速度提高了1.7倍。虽然我们针对直线加速器将标准算法进行了改进,但是由于改进方法基于对称性思想,对于任何具有对称性的加速器,该方法都可以用于加快模拟速度。

关 键 词：linear accelerator numerical simulation space-charge effect particle in cell algorithm SYMMETRY 

分 类 号：TL53[核科学技术—核技术及应用]