Document Type

Article

Publication Date

4-4-2018

Department 1

Physics

Abstract

Argon and xenon ion velocity distribution functions are measured in Ar-He, Ar-Xe, and Xe-He expanding helicon plasmas to determine if ion beam velocity is enhanced by the presence of lighter ions. Contrary to observations in mixed gas sheath experiments, we find that adding a lighter ion does not increase the ion beam speed. The predominant effect is a reduction of ion beam velocity consistent with increased drag arising from increased gas pressure under all conditions: constant total gas pressure, equal plasma densities of different ions, and very different plasma densities of different ions. These results suggest that the physics responsible for the acceleration of multiple ion species in simple sheaths is not responsible for the ion acceleration observed in expanding helicon plasmas.

DOI

10.1063/1.5021941

Version

Version of Record

Required Publisher's Statement

This article is available on the publisher's website: https://aip.scitation.org/doi/10.1063/1.5021941

Available for download on Saturday, April 04, 2020

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