微通道板噪声因子与工作电压关系研究

Study on the Relationship between Noise Factor and Working Voltage of Microchannel Plate

为了解决微通道板噪声因子的测量问题,提出了一种测量像增强器光电阴极灵敏度和信噪比,从而测量出微通道板噪声因子的方法 .根据该方法,分别在不同阴极电压、微通道板电压以及阳极电压条件下测量了微通道板的噪声因子.测量结果表明,当阴极电压、微通道板电压以及阳极电压分别变化时,微通道板的噪声因子会随之变化.微通道板电压对噪声因子的影响最大,阳极电压的影响最小.微通道板电压每增加100 V,噪声因子大约增加0.11,而阳极电压每增加100 V,噪声因子大约增加3.3×10^-4.微通道板工作电压提高,意味着电子碰撞能量提高,同时也意味着二次电子发射系数提高,而根据现有微通道板噪声理论,微通道板的噪声因子会减小,但实测结果却相反.造成这一矛盾的原因是在现有微通道板噪声理论中,仅仅考虑了二次电子发射系数、探测率、电子碰撞几率的因数,而未考虑到电子碰撞能量的因数,因此噪声理论需要进行修正.

In order to work out the measuring method of noise factor of microchannel plate,a method to measure the noise factor of microchannel plate by measuring the sensitivity of photocathode and signal to noise ratio of image intensifier is proposed. According to this method,the noise factor of microchannel plate is measured under different cathode voltage,microchannel plate voltage and anode voltage. The results show that the noise factor of microchannel plate change with the change of cathode voltage,microchannel plate voltage and anode voltage. The voltage of microchannel plate has the greatest influence on noise factor and the anode voltage has the least. When the voltage of microchannel plate is increased by 100 V,the noise factor increases by about 0.11. The noise factor increases about 3.3×10^-4 for every 100 V of anode voltage. The increase of working voltage of microchannel plate means the increase of electron collision energy and the increase of secondary electron emission coefficient. According to the existing noise theory of microchannel plate,the noise factor of microchannel plate will be reduced,but the measured results are increased. The reason for this contradiction is that in the existing noise theory of microchannel plate,only the influence of secondary electron emission coefficient,detection rate and electron collision probability on the noise factor are considered,but the influence of collision electron energy on the noise factor is not considered,so the noise theory needs to be revised.