Arc-Back Testing of Graphite

This paper describes a mercury-vapor tube and associated circuits used to obtain the arc-back rate of various grades of graphite which might be applied in ignitrons and other types of electronic tubes. The methods of test and results obtained are included. The tests indicate that the arc-back rate of a graphite anode can be reduced by degassing at 1,800 degrees centigrade and that this improvement is maintained at room temperature and at atmospheric pressure. It also is shown that anodes when not in operation get charged with arc-back causes of two classes¿those that can be persist regardless of heating and apparently are removed by the arc-back itself.