TY - JOUR

T1 - Foundations and interpretations of the pulsed-Townsend experiment

AU - Casey, M

AU - Stokes, Peter

AU - Cocks, Daniel G

AU - Bošnjaković, Danko

AU - Simonović, Ilija

AU - Brunger, Michael

AU - Dujko, Saša

AU - Petrović, Zoran

AU - Robson, Robert

AU - White, Ronald

N1 - Publisher Copyright:
© 2021 The Author(s). Published by IOP Publishing Ltd.

PY - 2021/3/25

Y1 - 2021/3/25

N2 - 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.

AB - 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.

KW - pulsed townsend experiment

KW - Brambring’s equation

KW - kinetic theory

KW - pulsed townsend governing equation

KW - transport coeffcient defnition

UR - http://www.scopus.com/inward/record.url?scp=85101735596&partnerID=8YFLogxK

U2 - 10.1088/1361-6595/abe729

DO - 10.1088/1361-6595/abe729

M3 - Article

VL - 30

SP - 1

EP - 11

JO - Plasma Sources Science and Technology

JF - Plasma Sources Science and Technology

SN - 0963-0252

IS - 3

M1 - 035017

ER -