Non-ideal plasma behavior of railgun arcs

A theoretical framework for modeling the characteristics of railgun plasma armatures is developed taking into account non-ideal transport properties and equation of state. The electrical resistivity of the plasma is calculated as a sum of contributions from electron-ion and electron-neutral collisions. The degree of ionization is calculated from the Saha equation with the appropriate lowering of the ionization potential and pressure calculated using non-ideal plasma theory. For electron-ion resistivity, we use the basic formulation of Khalfaoui for highly non-ideal plasma, smoothed and calibrated with respect to the results of Kurilenko & Valuev, Vorobiov et al and Kovitya. For electron-neutral resistivity, we use a formulation which allows the fitting of an infinite half-power series to experimentally determined energy spectrum of electron-neutral collision frequencies for a given atom. Finally, a steady-state magneto-gasdynamic model improved over earlier works is developed. In this model, the net Lorentz force exerting on the plasma armature is exactly accounted for.