为了辐照生物活细胞,束流须经由真空隔离窗引入大气环境中.在真空隔离窗的设计中,对结构、材料种类及其厚度的选择既要尽可能地减小束斑展宽,又要兼顾安全性.应用有限元分析软件对不同结构、不同材料的真空窗进行受力分析,模拟真空窗的形变和等效应力,运用强度理论考察候选真空窗的安全性;并运用SRIM程序模拟离子的小角散射、横向射程,计算入射离子的能量、真空窗材料及其厚度、空气层对束斑展宽的影响;最后提出真空窗适宜的结构、材料及厚度范围. In order to irradiate biological living cells, the beam should be introduced into the atmosphere via a vacuum isolation window.In the design of vacuum isolation windows, the choice of structure, material type and thickness should not only reduce the beam spot broadening but also Taking into account the safety of finite element analysis software for different structures and different materials of the vacuum window stress analysis, simulation of vacuum window deformation and equivalent stress, the use of strength theory to examine the safety of the candidate vacuum window; and the use of SRIM program simulation ions The small-angle scattering, the transverse range, the energy of incident ion, the material and the thickness of the vacuum window and the influence of the air layer on the broadening of the spot. Finally, the suitable structure, material and thickness range of the vacuum window are proposed.