The Stopping And Transmitting Characteristics Of Ion Barrier Film Of Microchannel Plate And Its Effect On Noise

The microchannel plate with ion barrier film is the core component of the Gen.Ⅲof low-light-level night vision technology,which plays a great role in the capability of modern night warfare.Ion barrier films can effectively inhibit positive ion feedback,which is the critical factor to determine the life of low-light image tube.However,the noise of microchannel plate increases due to the introduction of ion barrier films.Therefore,this paper has carried out a study on the Ion barrier films of MCP and its effect on noise.This paper summarizes the development status of night vision device and ion barrier film.The physical process of charged particles interacting with ion barrier film was analyzed.The research focuses on using Monte-Carlo simulation method,using CASINO and SRIM software to establish a charged particle transmission model,and calculating the change curve of the permeability of the ion barrier film under different conditions.The noise characteristics of the ion barrier film are also studied.According to the calculation formula of the noise factor,the influence of different conditions on the ion barrier film noise factor is simulated by using the time differential method and the mixed programming scheme of C#and Matlab.The simulation results of electronic transmission characteristics of ion barrier films using CASINO software show that:the dead voltage of Al₂O₃film is about 245V and that of Be O film is about 240V.The electron transmittance of Be O film is slightly higher than that of Al₂O₃film.With the increase of incident electron energy and thin film thickness,electron transmittance increases gradually.Then a test system conforming to the structure and working state of the three-generation low-light image intensifier is established.The semi-membrane method was used to test the electron transmittance.The results show that with the increase of electron energy,the curve of simulation results and test results gradually coincide,and the overall gap is between 1%-5%.SRIM software was used to simulate the ion stopping characteristics of the film.The results show that the feedback positive ions are low-energy ions with higher nuclear blocking power than electron blocking power.With the increase of incident ion energy and thin film thickness,the ion blocking rate decreases gradually.Although the ion stopping ability of Be O film is inferior to Al₂O₃film,when the incident ion energy is 300e V,the two kinds of thin films’blocking ability of C,N and O is above 92%.Then,the noise factors of different film thicknesses are simulated,and it is found that with the decrease of incident electron energy,the increase of film thickness and the increase of film density,the noise generated by the image is larger.There is little difference between Al₂O₃and Be O noise factor,but Be O noise factor is smaller under the same conditions.Since the material,structure and thickness of the anti-ion feedback membrane are considered in the simulation,the key factors affecting the characteristics of the anti-ion feedback membrane can be determined.These research results can provide an important reference for improving the preparation parameters of the ion barrier film and improving the performance of the low-light image intensifier,so it has an important significance in the application of modern warfare.