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栅流是指电子管栅极和阴极之间的电流.由于电子管正常工作时栅极对阴极总保持一定的负电压,所以一般管子的栅流都不大,通常放大用的电子管约在10~(-8)～10~(-9)安之间,在一般情况下不会影响电子管的工作.但目前科学的发展提出了放大10~(-12)～10~(-17)安微电流的任务,例如质谱仪集电极所获得的电流、天文光电测光由微弱星光引起的光电流、各种辐射在电离室中产生的电离电流等等.由于要放大的对象比棚流小好几个数量级,栅流的影响便显得极为严重,使一般电子管无法胜任.
The gate current is the current between the gate and the cathode of the tube.As the normal operation of the tube gate to the cathode always maintain a certain negative voltage, so the general tube gate flow is not large, usually about 10 ~ -8) ~ 10 ~ (-9) A, under normal circumstances will not affect the work of the tube.But the current development of science put forward to enlarge 10 ~ (-12) ~ 10 ~ (-17) A micro-current task Such as the current obtained at the mass spectrometer’s collector, astronomical photometry light currents caused by faint stars, ionizing currents generated by various radiation in the ionization chamber, etc. Since objects to be amplified are several orders of magnitude smaller than the shed, The influence of the gate current becomes very serious, making the general tube can not be competent.