Charged Particle Distributions and Heat Transfer in a Discharge Between Geometrically Dissimilar Electrodes: From Breakdown to Steady State

The low-current electric discharge from a fine wire anode to a planar cathode in atmospheric pressure air is numerically simulated from high-voltage prebreakdown through electron temperature growth, then ionization and consequent current growth to steady state, limited by a ballast resistor in the external circuit. Conservation of number ~mass! for ions and electrons, Gauss’ law for the self-consistent electric field, and energy conservation for electrons have been solved from breakdown to steady state in a body fitted coordinate system generated specifically for these two geometrically dissimilar electrodes. To facilitate the discussion of the results, the discharge has been categorized under ~a! electron acceleration period, ~b! charged particle generation period, ~c! current increase and voltage drop period, and ~d! current and voltage stabilization period. Results are given for transient electron, ion, and temperature distributions in the gap as well as current growth and voltage drop across the gap. Heat flux from the discharge to the wire is calculated. The numerical simulations were compared with experiments performed under the same conditions on a wire bonding machine with very close correspondence. Disciplines Engineering | Mechanical Engineering Comments Suggested Citation: Qin, Wei, Ira M. Cohen and Portonovo S. Ayyaswamy. (2000). Charged particle distributions and heat transfer in discharge between geometrically dissimilar electrodes: From breakdown to a steady state. Physics of Plasmas. Vol. 7(2). Copyright (2000) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Physics of Plasmas and may be found at http://scitation.aip.org/getpdf/servlet/ GetPDFServlet?filetype=pdf&id=PHPAEN000007000002000719000001&idtype=cvips&prog=normal&doi=10.1063/ 1.873858 This journal article is available at ScholarlyCommons: http://repository.upenn.edu/meam_papers/175 Charged particle distributions and heat transfer in a discharge between geometrically dissimilar electrodes: From breakdown to steady state Wei (Ivy) Qin, Ira M. Cohen, and P. S. Ayyaswamy The University of Pennsylvania, Department of Mechanical Engineering and Applied Mechanics, Philadelphia, Pennsylvania 19104 ~Received 14 December 1998; accepted 18 October 1999! The low-current electric discharge from a fine wire anode to a planar cathode in atmospheric pressure air is numerically simulated from high-voltage prebreakdown through electron temperature growth, then ionization and consequent current growth to steady state, limited by a ballast resistor in the external circuit. Conservation of number ~mass! for ions and electrons, Gauss’ law for the self-consistent electric field, and energy conservation for electrons have been solved from breakdown to steady state in a body fitted coordinate system generated specifically for these two geometrically dissimilar electrodes. To facilitate the discussion of the results, the discharge has been categorized under ~a! electron acceleration period, ~b! charged particle generation period, ~c! current increase and voltage drop period, and ~d! current and voltage stabilization period. Results are given for transient electron, ion, and temperature distributions in the gap as well as current growth and voltage drop across the gap. Heat flux from the discharge to the wire is calculated. The numerical simulations were compared with experiments performed under the same conditions on a wire bonding machine with very close correspondence. © 2000 American Institute of Physics. @S1070-664X~00!00902-2#