Theory of the Double Probe at High Gas Pressure†

Abstract

It is shown that the mean electron energy in a uniform steady plasma at high gas pressure can be obtained from the analysis of a plane double probe curve. If the motion of charges to the boundary is controlled by diffusion and mobility, their production by single electron collisions and their loss by charge neutralization on the wall, the electron temperature is found from a relation which is similar to that for probes at low pressure. The mechanism of selection of electrons of different energy by a probe at low gas pressure is contrasted with that at high pressure and the application of the theory to various physical systems is discussed.