Effective Evaluation of the Noise Factor of Microchannel Plate

Honggang Wang,Xiaoming Hu,Yang Lv,Yu Feng,Yujie Du,Yunsheng Qian

doi:10.1155/2015/781327

Honggang Wang, Xiaoming Hu + Show 4 more

Open Access

https://doi.org/10.1155/2015/781327

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Abstract

To improve the noise performance of microchannel plate (MCP), we have presented a method using the sine random signals with Poisson distribution as the noise-excitation for electron source. By using this method, the effective evaluation of noise characteristics of MCP has been implemented through measuring and analyzing its noise factor. The results have demonstrated that the noise factor of filmed MCP is lower than 1.8. Additionally, as the open area ratio and the input electron energy are 72% and 400 eV, respectively, the noise characteristics of unfilmed MCP are improved evidently. Moreover, larger open area ratio, higher input electron energy, and higher voltage across the MCP all can reduce effectively the noise factor within a certain range. Meanwhile, the ion barrier film extends the life of image tube but at the cost of an increased noise factor. Therefore, it is necessary that a compromise between the optimum thickness of ion barrier film, open area ratio, input electron energy, and voltage across the MCP must be reached.

Highlights

Modern photoelectric imaging intensifiers for various applications often employ a microchannel plate (MCP) to generate electronic gain by secondary electron multiplication [1]
In accordance with the above measuring conditions, we have determined the value of signal-to-noise ratio at the input end (SNRin) as 48.54 and measured noise factor (NF) of various MCP, including BB, BF
For the thirdgeneration image tubes, if these ions are allowed to escape from the MCP and interact with the GaAs photocathode, they can cause irreversible damage to the cesium and oxygen (Cs-O) activation layer causing rapid decay in the cathode photoresponse

Summary

Introduction

Modern photoelectric imaging intensifiers for various applications often employ a microchannel plate (MCP) to generate electronic gain by secondary electron multiplication [1]. According to the requirements of NF measurement, the bottleneck is the significant difference between very low input current density (10−11–10−10 A/cm2) and high SNR, which leads to the fact that the input current noise is overwhelmed by the ambient interference noise, and the measurement becomes difficult. To address this problem, we present a method using the sine random signals with Poisson distribution as the noise-excitation for electron source, through which the varying filament current satisfying the measurement requirements is generated. The results agree with the practical condition of MCP; in other words, the objective evaluation of the noise characteristics of MCP can be achieved by determining NF, which has been experimentally verified

Evaluation Method

Experimental Results

Conclusions