Influence of surface potential barrier on escape probability of gradient-doping negative electron affinity (NEA) GaN photocathode was studied. Electron energy distribution and escape probability are calculated and compared with those of uniform-doping GaN photocathode. It shows that gradient-doping NEA GaN photocathode can obtain higher electron escape probability. And barrier I has an evident influence on escape probability while barrier Ⅱ has limited influence. Photocurrents of two GaN photocathodes are measured with a multi-information-test system. Experimental results show that gradient-doping GaN photocathode has higher escape probability. Obvious effect on escape probability can be found by barrier I from Cs-activation while barrier Ⅱ from Cs/O-joint-activation has little impact.

To improve resolution of a low-light image intensifier,simulation of electronic transport in a micro-channel plate(MCP) is made.Field distribution is obtained by calculating electron optics with numerical method.Distribution of photoelectron on fluorescent screen is determined by tracing electron trajectory in MCP.Influence of MCP tilt angle,channel diameter,voltage on electronic transport and resolution of image intensifier are studied.It shows that MCP has good electronic transport characteristics,image intensifier has good modulation transfer function(MTF) and high resolution at a title angle of 14°,channel diameter of 5.0 μm,a voltage of 900 V.