Effects of ionized oxygen on primary and secondary emission, and total current of a CFA

The total current of a crossed-field amplifier (CFA) was found to be dependent upon a combination of primary emission and secondary multiplication. In any given CFA, low total emission could be caused by deficiency of either primary emission or secondary multiplication. In the example studied here, the principal shortcoming was a deterioration in secondary emission with running time caused by dissociation of oxide at the cathode surface. A method was devised to "implant" oxygen into the cathode surface in the manufacturing cycle as part of processing and testing of the CFA. This preserved the oxide under CFA operating conditions and maintained total CFA current during life.