为了得到X射线条纹相机中CsI光阴极的高能电子份额数据,通过蒙特卡罗方法建立模型来研究CsI光阴极在X射线照射下的光电发射特性。研究了CsI光阴极厚度为100~1 000nm、入射X射线能量为1~30keV时的二次电子(SE)能量分布。模拟结果显示,入射X射线的能量越高、CsI光阴极的厚度越大,从CsI光阴极出射的二次电子中高能电子(大于50eV)的份额越高,在入射X射线能量为30keV、CsI光阴极厚度为1 000nm时,出射电子中的高能电子份额可以达到10.8%。但是当CsI光阴极厚度保持为100nm、而入射X射线能量大于15keV时,高能电子份额维持在3.4%左右而不再随入射X射线的能量增加而增加。 In order to obtain high-energy electron fraction data of CsI photocathode in X-ray streak camera, the model of the CsI photocathode under X-ray irradiation was established by Monte-Carlo method. The energy distribution of secondary electrons (SE) at a CsI photocathode thickness of 100-1000 nm and an incident X-ray energy of 1-30 keV was studied. The simulation results show that the higher the incident X-ray energy is, the larger the thickness of CsI photocathode is. The higher the proportion of high-energy electrons (greater than 50eV) in the secondary electrons emitted from the CsI photocathode, When the photocathode thickness is 1 000 nm, the share of high-energy electrons in the outgoing electrons can reach 10.8%. However, when the CsI photocathode thickness is maintained at 100 nm and the incident X-ray energy is greater than 15 keV, the share of high-energy electrons remains at about 3.4% and no longer increases with increasing incident X-ray energy.