The Influence of Ion – Neutral Collisions in the Plasma Sheath on the Ion Current to an Electrostatic Probe: Monte Carlo Simulation

✍ Scribed by D. Trunec; P. Španěl; D. Smith

• Publisher: John Wiley and Sons
• Year: 1995
• Tongue: English
• Weight: 534 KB
• Volume: 35
• Category: Article
• ISSN: 0005-8025
• DOI: 10.1002/ctpp.2150350304

✦ Synopsis

Abstract

We have carried out Monte Carlo simulation of the motion of Ar^+^ ions in the space charge sheath surrounding a cylindrical Langmuir probe. From these simulations the percentage of ions crossing the sheath boundary that are collected by the probe have been determined and thus the ion currents to the probe have been calculated. It is shown that the collisions of ions with neutral helium gas atoms in the sheath increase the percentage of ions collected by the probe above that predicted by collisionless orbital motion limited current (OMLC) theory and that the exponent, χ, of the power law dependence, i~+~∼U, of the ion current, i~+~, on the probe voltage, U~p~, increases above the value 0.5 predicted by OMLC theory. The results of the simulations are compared with recent Langmuir probe measurements made in flowing afterglow plasmas.