LaB6空心阴极中毒特性

LaB_6阴极与其他类型阴极相比具有电子发射电流密度大等优点,已广泛用于电推进、高发射密度电子枪等产品。为了研究LaB_6空心阴极中毒特性、识别LaB_6空心阴极主要失效模式,分别对LaB_6空心阴极暴露大气后性能变化特征和引起性能变化的原因进行了研究。结果表明:LaB_6空心阴极在暴露大气后表面吸附大量中毒气体,出现了发射体表面逸出功增加、发射体短期中毒现象。此时空心阴极的放电电压和阴极顶温度均有所上升,经过短期工作后放电电压和阴极顶温度均恢复初始状态。但LaB_6空心阴极严重中毒后,并不能通过加热和离子轰击方式去除表面生成的氧化物。因此,可以在实验过程中通过监测空心阴极的阴极顶温度和阳极电压变化间接表征空心阴极发射体状态。

Poisoning characteristics of LaB6 hollow cathode

Compared with other cathodes, LaB₆ cathode has the advantage of high electron emission current density, and has been widely used in electric propulsion, high emission density electron gun and other products. In order to analyze the poisoning characteristics of the LaB₆ hollow cathode and identify its failure mode, the performance change features and reasons of LaB₆ hollow cathode exposed to atmosphere were studied. The results show that the LaB₆ hollow cathode adsorbs a great deal of poisonous gas on the surface of the emitter during exposure to the atmosphere, and while the work function from the emitter surface increases, the emitter appears short-term poisoning phenomenon. The discharge voltage and hollow cathode plate temperature are increased, and the discharge voltage and cathode top temperature are restored to the initial state after short-term operation. However, if the poisoning phenomenon of LaB₆ hollow cathode is serious, the oxide generated on the surface can not be removed by heating and ion bombardment. Therefore, the emitter state of hollow cathode can be indirectly characterized by monitoring the change of cathode temperature and anode voltage during the test.