Design and evaluation of a computer controlled Langmuir probe system for glow discharge plasma diagnostics

Abstract

An automated Langmuir probe system employing a microcontroller as the interface between the experiment and host computer is presented. The effects of the scanning rate of applied voltage and those of sputtered atom deposition on the measured plasma properties have been examined and are used to evaluate this automated system. Results show that the effect of scanning rate on the determined properties of charged particles is insignificant in the range of 120–800 ms per cycle over the 20-V range of applied voltage. Experiments indicate that the positive ion number densities determined are sensitive to sputtered atom deposition on the probe, while the plasma potential, electron temperature and electron number density are not affected appreciably.