Foundations and interpretations of the pulsed-Townsend experiment

Casey, M.J.E., Stokes, P.W., Cocks, D.G., Bošnjaković, D., Simonović, I., Brunger, M.J., Dujko, S., Petrović, Z.Lj, Robson, R.E., and White, R.D. (2021) Foundations and interpretations of the pulsed-Townsend experiment. Plasma Sources Science and Technology, 30 (3). 035017.

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Abstract

The pulsed-Townsend (PT) experiment is a well known swarm technique used to measure transport properties from a current in an external circuit, the analysis of which is based on the governing equation of continuity. In this paper, the Brambring representation (1964 Z. Phys. 179 532) of the equation of continuity often used to analyse the PT experiment, is shown to be fundamentally flawed when non-conservative processes are operative. The Brambring representation of the continuity equation is not derivable from Boltzmann's equation and consequently transport properties defined within the framework are not clearly representable in terms of the phase-space distribution function. We present a re-analysis of the PT experiment in terms of the standard diffusion equation which has firm kinetic theory foundations, furnishing an expression for the current measured by the PT experiment in terms of the universal bulk transport coefficients (net ionisation rate, bulk drift velocity and bulk longitudinal diffusion coefficient). Furthermore, a relationship between the transport properties previously extracted from the PT experiment using the Brambring representation, and the universal bulk transport coefficients is presented. The validity of the relationship is tested for two gases Ar and SF6, highlighting also estimates of the differences.

Item ID: 70512
Item Type: Article (Research - C1)
ISSN: 1361-6595
Keywords: Brambring s equation, kinetic theory, pulsed townsend experiment, pulsed townsend governing equation, transport coefficient definition
Copyright Information: © 2021 The Author(s). Published by IOP Publishing Ltd. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Funders: Australian Research Council (ARC)
Projects and Grants: ARC DP180101655
Date Deposited: 12 Apr 2022 03:29
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