O 2+ 离子穿过碳膜引起的前后表面电子发射

Abstract

测量了入射能为1.9 ~11.3 keV/u 的O2+ 离子穿过碳膜诱导的前向、后向(分别对应出射表面和入射表面)电子发射产额。实验中，通过改变入射离子的能量和流强，系统地研究了电子能损和离子束流强度对前向、后向电子发射产额的影响。结果表明，在本实验的能量范围内，前向、后向电子发射产额与对应表面的电子能损有近似的正比关系，而与束流强度无关。分析还发现引起后向电子发射的动能阈值约为0.2 keV/u，势能电子发射产额约为1 e-/ion。 We have measured the secondary electron emission yields in forward and backward directions from the carbon foils, which are penetrated by O2+ ion of the energy form 1.9 to 11.3 keV/u. In the experiment, the role of electronic energy loss and ion beam intensity in forward and backward electron emission yields have been systematically studied by changing the projectile ion energy and ion beam intensity. The results show that,forward and backward electron emission yields are approximately proportional to the electron energy loss at the exit surfaces and entrance surfaces respectively, and they are independent of the ion beam intensity. Further analyses show that, the kinetic energy threshold for the backward electron emission is about 0.2 keV/u, where the electron emission yield due to the potential energy deposition was roughly 1 e-/ion in the experiment.