Its not a difference between NATO Cathode and Russian cathode.I had some time to think about this last night. Its difference between depleted cathode exposed to air while hot forming irreversible tungsten compound. Gas lasers use the later as the plasma current tears conventional tungsten cathodes apart.
There are a couple of active compounds used in cathodes world wide. One activates fine at diffusion vacuum and can reactivate a few times. Other uses tungsten as sponge to hold a mixture which slowly forms an active layer about 100 micron thick on surface that slowly depletes and exposure to air when hot ruins it forever.
As soon as I can later today I will scan you internal laser factory document explaining why you need higher vacuum for Dispenser cathode. Blame the Dutch, it was their idea.
Steve
Last edited by mixedgas; 08-18-2018 at 07:24.
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