Cathode performance in background of residual gases

It is shown to what extent residual gases appearing in microwave tubes affect the characteristics of the cathode, before and during operations. Tests were carried out on cathodes of the metal capillary type. The reaction takes place on the emitting surface of the cathodes, so the information retrieved can be applied to other types of cathode. Tungsten and osmium-coated tungsten cathodes were tested. The gases investigated were the following: helium, argon, nitrogen, carbon monoxide, carbon dioxide, oxygen, and methane