Study On The Damage Mechanism Of High Energy Particles To The Internal Structure Of Vacuum Image Tube

Positive charged particles in the image tube will gain energy and move towards the photocathode under the strong electric field of the device.These particles will bring false gain and noise signals while damaging the micro channel wall,photocathode and other structures.The above phenomenon is called ion feedback.The methods of coating,manufacturing curved channel MCP and bulk conductive MCP can effectively weaken the ion feedback effect,but at the same time,it also brings a series of new challenges such as high process requirements and reduced resolution.The development of low light night vision technology at home and abroad still requires exploring new ways to solve the ion feedback problem.This paper conducts in-depth theoretical and experimental research on the dynamic process of positive ions inside the image tube and ion bombardment of cathode targets.The paper uses COMSOL software to establish a two-dimensional model of the image tube,calculates the electric field distribution inside the MCP based on finite element analysis,and realizes the trajectory simulation of hydrogen ions in the image tube model.The energy distribution curve and angle distribution curve of hydrogen ions bombarding the cathode are obtained,Using the SRIM ion transport program to characterize the interaction mechanism between particles and solid materials,we obtained the backscattered energy spectra of hydrogen ions of 50e V,200e V,and 500e V bombarding the microchannel inner wall material lead silicate glass at different angles.Finally,we simulated the projection range of H~+,C~+,N~+,and O~+ions in the Ga As cathode and their damage to the cathode.The paper draws the following conclusions:The proportion of particles in the low energy segment of the hydrogen ion energy distribution curve is large,and the curve shows a unilateral downward trend,The angle distribution curve is similar to a normal curve.In SRIM backscattering simulation,although the energy and incident angle of hydrogen ions are different,the backscattering energy spectrum curve has a similar trend of change.In the simulation calculation results of material damage,H~+causes almost no damage to the interior and surface of the cathode material,while C~+,N~+,and O~+cause more severe lattice atom displacement damage to the Ga As layer and sputtering of surface cesium and oxygen elements.