AUXILIARY DISCHARGE IN A THERMIONIC CONVERTER.

The voltage drop in the low-voltage arc of a cesium thermionic converter is about 0. 5 V under optimum conditions. Experiments show that it is possible to reduce this drop by means of an auxiliary inert-gas discharge. The optimum parameters of the auxiliary emitter and of the auxiliary discharge is very sensitive to the electrode work function. The required emitter work function can be achieved by adding barium vapor at a low pressure so that the barium does not affect the discharge parameters. A simple physical model leads to a good qualitative agreement with experiment. There is a fundamental limit on the parameters of a converter with an auxiliary discharge.