低能小型医用回旋加速器谐振腔的有限元分析

Analysis of RF cavity for a small medical cyclotron with low energy by FEM

应用有限元方法分析了一台小型医用回旋加速器的谐振腔.以PC机为平台,采用ANSYS软件进行建模,对腔体的谐振频率、空载品质因数进行了研究,探讨了微调电容间距、网格剖分精度以及建模方法对计算结果的影响.回旋加速器谐振腔不是一个严格的封闭腔体,结构复杂.为减少计算量,根据其物理特性对腔体做了封闭处理,研究发现,这一简化的模型对计算精度的影响不大.计算结果和实际测量结果的误差在工程允许的范围之内,表明基于有限元的软件能够很好地计算类似回旋加速器高频谐振腔这样具有复杂边界的腔体结构,可用于加速器的物理设计及工程设计.

A small medical cyclotron cavity with low energy was analyzed by 3D finite element method （FEM）. A computing model was constructed by using ANSYS on personal compeers to study the RF resonant frequency and quality factor. The influence of the tuning capacitor gap,the cavity mesh and the model construction method were also discussed. The cyclotron cavity is not a strict closed structure, which would lead to a great quantity of computation. According to its electromagnetic physical nature, a closed model was used. The numerical experiment results showed that this simple model has no obvious influence on the computing results. The errors between the computing values and the measuring ones are within allowable limits, showing that the software based on FEM can simulate the cavity with complex boundaries. The work can be refererred to the further conception and the engineering design of the cavity.