TY - JOUR
T1 - Foundations and interpretations of the pulsed-Townsend experiment
AU - Casey, M. J.E.
AU - Stokes, P. W.
AU - Cocks, D. G.
AU - Bošnjaković, D.
AU - Simonović, I.
AU - Brunger, M. J.
AU - Dujko, S.
AU - Petrović, Z. Lj
AU - Robson, R. E.
AU - White, R. D.
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 - Brambring s equation
KW - kinetic theory
KW - pulsed townsend experiment
KW - pulsed townsend governing equation
KW - transport coefficient definition
UR - http://www.scopus.com/inward/record.url?scp=85101735596&partnerID=8YFLogxK
UR - http://purl.org/au-research/grants/arc/DP180101655
U2 - 10.1088/1361-6595/abe729
DO - 10.1088/1361-6595/abe729
M3 - Article
AN - SCOPUS:85101735596
SN - 0963-0252
VL - 30
JO - Plasma Sources Science and Technology
JF - Plasma Sources Science and Technology
IS - 3
M1 - 035017
ER -