Probe Technique for Measuring the Bohm Coefficient, Space-Charge Probe Layer Thickness, and Ion Mass

Abstract

We propose measuring the Bohm coefficient, thickness of the space-charge probe layer, and ion mass in Maxwellian low-pressure plasma based on the results of standard probe measurements using the Bohm effect, Boltzmann law, and “3/2” law in the case of their validity for the studied plasma. This possibility was implemented by comprehensive probe diagnostics of high-frequency xenon plasma of an induction discharge at a pressure of 2 mTorr. Analysis of the obtained results showed that these laws and the Bohm effect are valid with “engineering” accuracy, which made it possible to find Bohm coefficient C_BCyl ≈ 1.23 for a cylindrical probe, which served as the basis of the proposed method.