Keywords: 
• 第一镜 /
• 再沉积 /
• 挡板 /
• 蒙特卡罗方法

Abstract: How to improve the protective effect of the first mirror is urgent for tokamaks at present.Buffer is one of the efficient methods to reduce the impurity redeposition on the first mirror.In order to study the protective effect of the buffer,the physical model of the particle redeposition on the first mirror is established with the Monte Carlo method on the basis of the parameters and experiments of the HL-2A tokamak.Particle redepositions on the first mirror are simulated under different conditions,including the cases without buffer and with cone buffer.The simulation results match well with the experimental results.The accuracy of the model is verified,and the simulation is efficient for providing theoretical basis for the protection of the first mirror.