Experimental Research on Electron Scrubbing of Microchannel Plates with High Aspect Ratio
The electron scrubbing experiment is of great significance for evaluating the performance parame-ters of microchannel plates(MCPs),such as body resistance,gain,cumulative extracted charge and lifetime.Two MCPs with aspect ratio of 80∶1,pore size of 6 μm,and outer diameter of 25 mm are separately investigated using an electron scrubbing system in a 5 × 10-5 Pa vacuum equipment,one of the MCPs is coated with alumina thin film.By changing the scrubbing time,scrubbing dosage,scrubbing times,and MCP working voltage,the electron scrubbing process is investigated.The scrubbing times,total scrubbing time,and cumulative extracted charge of the two MCPs are 21 and 55 times,1134 and 4460 minutes,263 and 2329 mC,respectively.By testing the relationship between MCP body resistance,gain,and operating voltage before and after electron scrubbing,as well as the relationship between gain and scrubbing dose,the effects of electron scrubbing process on MCP performance parameters are evaluated in detail.The results show that when performing high-dose scrubbing,a small position gap between the electron gun and MCP can cause MCP damage due to severe heating during the scrubbing process.For the traditional 80∶1 MCP,the stable body resistance value after electron scrubbing is higher than that before scrubbing,while for the MCP coated with alumina film,the stable body resistance value after scrubbing is lower than that before scrubbing.After scrubbing,when the MCP body resistance and gain are imme-diately tested,the test results are relatively small;as the waiting time extends,the body resistance and gain are gradually increase and tend to stabilize.After each scrubbing,comparing the immediately tested body resistance values of the MCP can effectively determine whether the state of the MCP during the scrubbing process is nor-mal.As the scrubbing dose increases,the gain of MCP rapidly decreases and tends to stabilize quickly under low operating voltage.The cumulative extracted charge of coated MCP can exceed 2329 mC,and the stable gain at different operating voltages is within the range of 5-300.
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