三代管MCP离子阻挡膜研究

三代管中GaAs光电阴极的表面Cs-O层经不住正离子的轰击,但在MCP的通道内,由于二次电子倍增,在MCP通道的输出端,电子密度较大,所以MCP通道内的残余气体分子就会被电离,正离子在电场的作用下向阴极方向运动,最终轰击阴极的表面Cs-O层,使阴极的灵敏度衰退.所以在MCP的输入端制作一层Al₂O₃离子阻挡膜对延长阴极的寿命是至关重要的作用.本文介绍了MCP离子阻挡膜的离子阻挡和电子透射原理,离子阻挡膜厚度的确定以及离子阻挡膜的制作工艺.

ION BARRIER OF MCP IN THE THIRD GENERATION IMAGE INTENSIFIER

The surface Cs-O layer of GaAs photocathode can’t withstand the bombardment of positive ion.At the exit of microchannel of MCP,the quantity of electrons are very crowded,and the probability of ionization of residual gas molecules within the microchannel of MCP is also very high.Ionized gas molecules are accelerated by electronic field and moves toward the cathode and at last bombard cathode surface.This will damage the cathode surface and cause the decay of cathode sensitivity.In order to keep the Cs-O layer of cathdode surface from bombardment of ionized molecules,a ion barrier should be placed on the input side of MCP.Ion barrier of MCP is very important to prolong the lifetime of GaAs photocathode.This paper described the principle of ion stopping and electron transmission of ion barrier on MCP input side,illustrated the choosing method of thickness of ion barrier and explained making technique of ion barrier.