A quasi-one-dimensional theoretical model of ionization waves propagating in a shielded capillary discharge is developed for high values of the electric field to the gas density ratio. The model assumes a beam-like electron distribution function and takes into account both radial and axial components of the electric field, and the experimentally measured cross sections of the ionizing and elastic electron - atom collisions for argon. Steady-state solutions have been obtained numerically for cathode directed ionization waves associated with virtual anode (VA) propagation as well as for anode directed ionization waves associated with virtual cathode (VC) propagation. The VA (or VC) is initiated and observed experimentally when both the cathode (or the anode) and the coaxial shield are under the same electric potential. The numerical solutions demonstrate that the VA may propagate with much lower wave velocity than the VC in the same capillary. This fact agrees with the experimentally observed behavior of ionization waves in a shielded capillary filled with argon at low pressures.
|Title of host publication
|Edit American Physical Society, 42nd Annual Meeting of the APS Division of Plasma Physics combined with the 10th International Congress on Plasma Physics October 23 - 27, 2000 Québec City, Canada Meeting ID: DPP00
|Published - 1 Oct 2000