CMSIUM-OXYGEN-SILVER PHOTOELECTRIC CELL 



337 



1. Formation of a Silver Oxide Film on Surface of Cathode 

 The cells are sealed to a high vacuum exhaust system and baked 

 out at 400° C. The next step is the oxidation of the surface. It was 

 found that oxidation by a glow discharge in oxygen was the most 

 suitable method. This oxidation could not be done quantitatively 

 and uniformly over the front surface of the cathode because of surface 

 irregularities in the silver and because of variations in the physical 

 conditions of the surface. Means were therefore sought to obtain a 



Fig. 1 — Western Electric 3A photoelectric cell. 



uniform surface and one that would be the same in all cells, independent 

 of irregularities that could not be avoided, which were due to past 

 history. 



To accomplish this, electrolytic oxygen is admitted to the exhaust 

 system and the cathode is oxidized by a glow discharge until com- 

 pletely black. Then the circuit is held closed while the cathode is 

 heated by ion bombardment until the silver oxide is decomposed, 

 leaving a bright matte surface. After cooling, this process is repeated. 



