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UBC Theses and Dissertations

An analogue computer study of the Townsend and linear Z-pinch gas discharges Gallaher, Donald Frederick McGeer


This thesis describes a study of gas discharges employing analogue computing techniques. Two discharges are examined: The extensively documented Townsend discharge and the recently investigated linear z-pinch discharge of plasma physics. The Townsend discharge theory is presented, with theoretical and experimental results given for the gas ionization coefficients ∝, ɤ and the attachment coefficient ƞ. Simulation of the general Townsend equation including ∝, ɤ and ƞ is described and an error analysis is given. Computer ionization curves are generated from experimental values of ∝, ɤ and ƞ in three common gases and compared with corresponding experimental ionization curves. Townsend’s empirical equation for ∝is used to extend ionization curves to relatively large values of E/p. Theoretical formulae are presented for the primary ionization coefficient in neon-argon gas mixtures. The z-pinch discharge in the case of infinite plasma conductivity is discussed and the snowplow equation for the time variation of the plasma tube radius is derived. An analogue simulator for the snowplow equation is presented and an error analysis given. Analogue computer radial collapse curves are generated for argon and nitrogen and comparisons are made between analogue, digital computer and experimental collapse curves. It is concluded that the analogue computer is well suited to the solution of problems involving the Townsend and z-pinch discharges. The possibility of treating magnetohydrodynamic power generation by analogue methods is mentioned.

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