Cathode emission characteristics in a stream of ionized gas

Theoretical findings in earlier investigations by several workers on the processes taking place at electrodes of various devices in the flow of an ionized gas are found to be inconsistent with experiment in many respects. The present paper emphasizes the creation of such conditions that would promote a reliable interpretation of the experimental results obtained. The experiments were conducted for argon and argon-potassium plasma flows, the gas was heated in a plasmatron, the measuring electrodes were located across the gas flow, and the cathode was heated by an external source. Particular attention is given to the study of diffusion discharge under specified conditions of the argon and argon-potassium plasma for cathodes made from different metals. The investigation in the argon plasma was carried out in order to compare the character of voltage dependence of the current for nonactivated cathodes and potassium-activated cathodes. The experimental results did not corroborate the theoretical considerations of Liubimov (1965), which may partly be due to the surface of any electrode being coated with a layer of alkaline metal. Other discrepancies between theory and experiment are discussed.