Microchannel plate(MCP)is a key component in the low-level-light image intensifier.When the intensifier is working

positive ion feedback will be produced in front of the output surface of MCP.On the one hand

the ion feedback destroy the linear operation characteristics of the MCP;on the other hand

electron emission produced by these feedback ions results in the appearance of ion spots on the screen;furthermore

these positive ions can bombard the photo-electrical cathode and shorten the operating life of the cathode.At present

the effective method for minimizing the ion feedback phenomenon is to fabricate a super-thin Al

2

O

3

or SiO

2

thin film on the input surface of MCP.This thin film allows some electrons with certain energy and stop effectively positive ions to pass though it

thus the cathode can avoid the bombard from the feedback ions and prolong the operation life of image tube.In this paper

the silicon thin film with the thickness of 0.5~1 μm was firstly formed on an organic self-sustaining thin film using radio-frequency magnetron sputtering method.Next

the silicon thin film was attached on the MCP by discharging oxygen gas under a vacuum of 4~6 Pa.At the same time

silicon thin film was oxidized and the organic film was discomposed in this process.Finally a thin layer of SiO

2

ion-preventive feedback thin film satisfied the requirement was formed on the input surface of MCP.This fabrication method is very stable

and with a good reproducibility

the yield of this method is well above 90%.The technological parameters in the fabrication of sputtered Si thin film on the self-sustaining organic thin film were also reported in this paper.The structure and operating method of vacuum-discharge attaching was introduced and the advantage of ion-preventive feedback thin film fabricated by this method was shown.After the measurement

the electron transmittance characteristics though the ion-preventive feedback thin film for unfilmed and filmed MCPs were shown.The relationship between the thickness of the ion-preventive feedback thin film and the dead-voltage(characterize the electron transmittance propertied through the film)was given.The electron transmittance characteristics for SiO

2

ion-preventive feedback thin film was compared with that for Al

2

O

3

thin film.The electron transmittance characteristic of SiO

2

ion-preventive feedback thin film is better than that of Al

2

O

3

film(the dead-voltage is 220 V for SiO

2

thin film and 255 V for Al

2

O

3

film with the same film's thickness of 5 nm).At the end

it was pointed out that the emphasis of this project should be placed on the measurement of ion transmittance characteristics.