Residual gases in electron tubes after storage

Abstract

The composition of residual gases in electron tubes with impregnated cathodes was measured with the aid of an omegatron residual gas analyzer during operation after preparation and after storage. When stored electron tubes are switched on a considerable pressure increase occurs. It was found that hydrogen is the main component of the residual gases under these conditions. The partial pressure increase of hydrogen after switching on is about 14 times faster after storage than after preparation. It is supposed that hydrogen originates from an evaporated barium film from the cathode deposited on the inner surface of the anode. The barium film on the anode getters residual gases during storage and when the electron tube is switched on, hydrogen is released due to higher temperature and electron bombardment. The hydrogen was released at a rate of 1 × 10 −7 litre torr/sec. This value is compared with known parameters of the barium film.