Loss of Thermionic Emission in Oxide-Coated Cathode Tubes Due to Mechanical Shock

From the data presented here, it will be shown that large variations in the ability of a commercial pentode to maintain emission levels in the presence of shock are observed in groups of the same type from different production lots. Also, marked differences will be observed in a triode type having the same production date but exhausted on different days. It will be noted, too, that a standard A.S.T.M. diode displays only a very minor drop in activity after shock but when the diode has the cathode coating lengthened or a grid is inserted into the structure, the decrease in cathode activity with shock increases. Gas is observed momentarily immediately after shock in the "diodes" in which the grids are inserted. Replacing bumper type micas with smaller ones which do not contact the bulb result in less decrease in emission with shock, and increasing the number of micas in the standard diode has the effect of increasing the loss in activity after shock. In addition, it will be shown that the use of micas of different grades has, we believe, significant differences in the effect of shock on cathode activity.