Impurities introduced into kovar-envelope electron tubes by atmospheric corrosion

EXPERIENCE with a special design gas discharge tube, which has a kovar tubulation, indicated that a contaminant was appearing in trace amounts inside the tube during shelf life. Data are presented to support the proposal that the contaminant is hydrogen. A proposed mechanism of contamination follows. Water vapor in the air reacts with the kovar to produce hydrogen which then penetrates through the kovar into the tube interior. The surface of the kovar can be protected by a nickel chemi-plating process so that the device contamination is reduced to a negligible level even under accelerated conditions.