HIAF-BRing同步加速器双向涂抹注入优化和粒子跟踪模拟

发布时间：2018-04-28 01:38

本文选题：强流重离子加速器装置 + 双向涂抹注入　；参考：《中国科学院大学(中国科学院近代物理研究所)》2017年博士论文

【摘要】：粒子加速器是核物理研究的重要平台,自从它在二十世纪三十年代问世以来,其一直随着时代的发展向着更高的性能进行突破。如今,为了满足我国核物理研究对高流强重离子束的需求,中国科学院近代物理研究所开始建造我国新一代重离子加速器——“强流重离子加速器装置”(HIAF)。HIAF建成后,它将能够提供国际同类装置中最强的中低能脉冲重离子束流,输出最高功率的短脉冲、强聚焦、高能量重离子束团。该加速器装置由强流超导离子源SECR、强流超导离子直线加速器i Linac、磁刚度为34Tm的增强器BRing、磁刚度为13Tm的高精度环形谱仪SRing以及多个实验终端和相关配套设施构成。BRing作为HIAF的主环,其设计引出粒子数为1×10~(11)(~(238)U~(34+))。为了达到如此高的引出粒子数,同时降低共振损失的风险,BRing选择了双向涂抹注入方法。双向涂抹注入方法是由C.R.Prior在二十世纪九十年代提出的,其利用一块倾斜放置的静电偏转板偏转注入束,同时利用凸轨磁铁在注入点处形成水平和垂直方向的局部凸轨,通过改变注入过程中局部凸轨的高度,完成在环形加速器内的多圈注入,同时在水平和垂直相空间进行涂抹。其优点为注入增益远高于典型的单向多圈注入,而且累积束的横向分布较为均匀,减弱了空间电荷效应。研究表明注入参数对双向涂抹注入的影响非常显著。为了得到高的注入增益和注入效率,本文对BRing的注入参数进行了优化。本文基于MATLAB编写了双向涂抹注入优化程序,该程序中利用多种近似方法减少了程序的计算量,应用了遗传算法提高了优化速度,实现了在现有计算条件下对BRing注入参数的优化。为了验证优化结果的正确性,本文利用ORBIT程序对BRing的注入过程进行了粒子跟踪模拟。ORBIT是一款粒子跟踪程序,其利用PIC的方法处理粒子间空间电荷效应。基于上述优化程序得出的注入参数模拟结果表明,注入113圈束流,注入效率为97.7%,最终注入增益为110.3倍,累积束的横向分布较为均匀,空间电荷效应引起的粒子工作点漂移为-0.02左右。该结果说明,优化程序是正确的,当前得到的优化结果满足了HIAF-BRing的累积粒子数要求。本文研究了多种注入参数偏离设定值对BRing注入效率的影响,包括注入束发射度增长、注入方向偏离、静电偏转板倾角安装误差、机器工作点偏离、凸轨磁铁电源延迟。研究结果表明,虽然注入参数偏离对注入效率有影响,但是注入效率可维持在95%以上,可以满足HIAF-BRing对累积粒子数的要求。
[Abstract]:Particle accelerator is an important platform for nuclear physics research. Since it came out in 1930s, particle accelerator has been developing to higher performance breakthrough with the development of the times. Today, in order to meet the needs of nuclear physics research in China for high current heavy ion beams, the Institute of Modern Physics of the Chinese Academy of Sciences began to build a new generation of heavy ion accelerator-"high current heavy ion accelerator device". It will be able to provide the strongest medium and low energy pulse heavy ion beam in the international equipment of the same kind, output the highest power short pulse, strong focus, high energy heavy ion beam cluster. The accelerator consists of a strong current superconducting ion source, I Linac, an intensifier with magnetic stiffness of 34Tm, a high-precision ring spectrometer SRing with magnetic stiffness of 13Tm, and several experimental terminals and related facilities as the main ring of HIAF. The number of produced particles is 1 脳 10~(11)(~(238)U~(34. In order to achieve such a high number of extraction particles and reduce the risk of resonance loss, BRing has chosen a bidirectional smear injection method. The bidirectional smear injection method was proposed by C.R.Prior in the 1990s. It uses an inclined electrostatic deflection plate to deflect the beam and a convex rail magnet to form a horizontal and vertical local convex rail at the injection point. By changing the height of the local convex orbit in the injection process, the multi-cycle injection is completed in the annular accelerator, and the smear is carried out in the horizontal and vertical phase space at the same time. The advantages are that the injection gain is much higher than that of the typical unidirectional multi-loop injection, and the transverse distribution of the cumulative beam is more uniform, which weakens the space charge effect. The results show that the effect of injection parameters on bidirectional smear injection is very significant. In order to obtain high injection gain and injection efficiency, the injection parameters of BRing are optimized. In this paper, a bidirectional smear injection optimization program based on MATLAB is developed. In the program, many approximate methods are used to reduce the calculation amount of the program, and the genetic algorithm is applied to improve the optimization speed, and the parameters of BRing injection are optimized under the existing calculation conditions. In order to verify the correctness of the optimized results, the particle tracking simulation of the injection process of BRing using ORBIT program. ORBIT is a particle tracking program, which uses the method of PIC to deal with the interparticle space charge effect. The simulation results of the injection parameters based on the above optimization program show that the injection efficiency is 97.7, the injection gain is 110.3 times, and the transverse distribution of the cumulative beam is more uniform. The drift of particle working point caused by space charge effect is about -0.02. The results show that the optimization program is correct, and the current optimization results meet the requirements of the cumulative particle number of HIAF-BRing. In this paper, the effects of various injection parameters deviations on the injection efficiency of BRing are studied, including the increase of injection beam emissivity, the deviation of injection direction, the installation error of electrostatic deflector inclination angle, the deviation of machine working point, and the delay of power supply for convex rail magnets. The results show that the injection efficiency can be maintained at more than 95%, although the deviation of injection parameters has an effect on the injection efficiency, which can meet the requirements of HIAF-BRing for cumulative particle number.
【学位授予单位】：中国科学院大学(中国科学院近代物理研究所)
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TL544

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