长寿命管必须具有长寿命的阴极。一般氧化物阴极在理想的二极管中也能实现较长的寿命,但是,在整管使用中往往不能给阴极提供适当的气氛,而使阴极短命。污染和清洁对阴极来说是两个对立的方面。管内环境的污染来源主要是水汽、有机蒸汽(苯、乙醚)和油蒸汽等。普通电子管一般采用扩散泵排气系统,这 Long-life tubes must have long-lived cathodes. General oxide cathode in the ideal diode can also achieve a longer life expectancy, however, the use of the whole pipe often can not provide the cathode with a suitable atmosphere, leaving the cathode short-lived. Pollution and cleaning are two opposite aspects of the cathode. The sources of pollution in the pipe environment are mainly water vapor, organic vapor (benzene, ethyl ether) and oil vapor. Ordinary tubes generally use diffusion pump exhaust system, which