大面积均匀轫致辐射场模拟及其源设计  

Simulation and source design of large area uniform bremsstrahlung field

作　　者：丁柏文 郝建红[1] 张芳[2] 赵强[2] 范杰清[1] 董志伟[2] Ding Baiwen;Hao Jianhong;Zhang Fang;Zhao Qiang;Fan Jieqing;Dong Zhiwei(School of Electrical and Electronic Engineering,North China Electric Power University,Beijing 102206,China;Institute of Applied Physics and Computational Mathematics,Beijing 100094,China)

机构地区：[1]华北电力大学电气与电子工程学院,北京102206 [2]北京应用物理与计算数学研究所,北京100094

出　　处：《强激光与粒子束》2024年第12期143-149,共7页High Power Laser and Particle Beams

基　　金：国家自然科学青年基金项目(12205024)。

摘　　要：基于蒙特卡罗方法建立了单环及双环平行电子束轰击钽靶模型,以此模拟环形二极管产生轫致辐射场的过程。模型选用电子束能量为1.5 MeV,钽金属靶厚度为200μm,并采用探测器计数方法对单环电子束在靶后10 cm产生的轫致辐射场剂量进行模拟研究。对于单环二极管结构,环内径是影响靶后轫致辐射场均匀性的主要因素,内径越大,中心剂量均匀性越差。相比环内径,环宽则主要影响辐射场的剂量大小,对于均匀性的影响较小。当单环内径为19 cm、外径为20 cm时,能得到最大面积为2 290.221 cm^(2)的均匀辐射场。双环二极管结构对比单环结构能得到更大面积的均匀辐射场。但外环环径的变化会导致辐射场剂量分布出现多级峰值,同时对辐射场各个区域的均匀性造成影响。模拟结果表明,通过在上述单环结构外侧添加内径为43.5 cm、外径为44.167 cm的同心外环,可将满足均匀度要求的辐射场面积增大至7 238.229 cm^(2)。Bremsstrahlung diode is an important device for obtaining large area uniform bremsstrahlung field in laboratory.In this paper,based on Monte Carlo method,a model of single and double ring parallel electron beam bombarding tantalum target is established to simulate the process of bremsstrahlung field generated by ring diode.The electron beam energy is 1.5 MeV,the tantalum target thickness is 200μm,and the dose of bremsstrahlung field generated by a single ring electron beam 10 cm behind the target is simulated by detector counting method.For singlering diode structure,the inner diameter of the ring is the main factor affecting the bremsstrahlung field uniformity behind the target,and the larger the inner diameter,the worse the central dose uniformity.Compared with the inner diameter of the ring,the ring width mainly affects the dose of the radiation field,but has little influence on the uniformity.When the inner diameter of a single ring is 19 cm and the outer diameter is 20 cm,a uniform radiation field with a maximum area of 2290.221 cm^(2) can be obtained.When the inner diameter of a single ring is 19 cm and the outer diameter is 20 cm,a uniform radiation field with a maximum area of 2290.221 cm^(2) can be obtained.The doubleloop diode structure can obtain a larger area of uniform radiation field than the single-loop structure.However,the variation of the outer ring diameter leads to multi-level peaks in the dose distribution of the radiation field,which also affects the homogeneity of each region of the radiation field.The simulation results show that by adding a concentric outer ring with an inner diameter of 43.5 cm and an outer diameter of 44.167 cm to the outside of the single ring structure,the radiation field area meeting the uniformity requirement can be increased to 7238.229 cm^(2).

关 键 词：X射线 环形二极管 轫致辐射 蒙特卡罗方法 均匀性 

分 类 号：TL501[核科学技术—核技术及应用]