高平均束流功率辐照加速器加速结构的研究

Study of Accelerating Structure for High Average Beam Power Irradiation Linac

本文介绍了10MeV/100kW的高平均束流功率工业辐照加速器束流动力学模拟结果及其加速结构的优化设计结果。加速器采用驻波双周期轴耦合结构,1个加速腔和1个耦合腔构成1个加速单元,其工作频率为325 MHz,工作模式为π/2,加速腔和耦合腔之间通过耦合狭缝在轴向以磁耦合的方式耦合在一起。使用SUPERFISH优化加速腔的有效分路阻抗、Kilp系数等关键参数。束流动力学方面,使用PARMELA模拟论证在粒子源提供2.5keV、500mA的电子束后,通过6个加速腔可得到10 MeV/100kW的平均束流功率。加速腔优化完成后使用CST对耦合腔进行了设计,此时由6个加速单元组成的加速结构有效分路阻抗为23.9 MΩ/m、无载品质因数为29 347,各加速腔与相邻的耦合腔耦合系数为4.7%,工作模式与其相邻模式的最小频率间隔为2 MHz,每个加速单元功耗为290kW。

An accelerating structure to obtain the average beam power of 10 MeV/100 kW for high average beam power industrial irradiation accelerator was developed.The results of beam dynamics studies and accelerating structure optimizations are as follows.The accelerator uses a bi-periodic standing wave on-axis coupling structure.An accelerating cavity and a coupling cavity form an accelerating structure unit.The operating frequency of the unit is 325 MHz atπ/2 mode.The coupling slots were used to couple the accelerating cavity and the coupling cavity together by magnetic coupling.The SUPERFISH code was used to optimize some key parameters like effective shut impedance and Kilp factor.The PARMELA code was used for beam dynamics studies.A 2.5 keV/500 mA electron beam was injected into an accelerating structure which consists of 6 accelerating cells to obtain the average beam power of 10 MeV/100 kW.The CST-MWS code was used to design the coupling cavity.The optimization results of the accelerator consisting of 6 accelerating structure units are that the effective shut impedance is 23.9 MΩ/m,the unloaded quality factor is 29 347,the coupling factor between every accelerating cavity and its adjacent coupling cavity is 4.7%,theπ/2 mode isolation bandwidth is 2 MHz,and the peak power loss is no more than 290 kW per unit.