On an Electric-Current-Carrying Discontinuity Driven Through Non-Conducting Gas by a Lorentz Force

摘要

A physical model is presented for an electric current carrying discontinuity separating two uniform states in a flowing gas. The physical model is composed of a thin shock wave followed closely by a thicker current sheet in which the viscosity and thermal conductivity are zero. The electrons and ions move only in the plane of the current sheet (in discontinuity fixed coordinates) and have no component of velocity in the streamwise direction. The momentum and energy exchange terms occurring in the species momentum and energy equations reduce to a particularly simple form based on a slightly ionized gas and a constant collision frequency model. Coulomb attraction causes the electron charge density to equal the ion charge density. A three fluid analysis (electrons, neutrals, and singly ionized ions) of this model is made for the case where the component of the magnetic field normal to the plane of the discontinuity is zero. The analysis results in a system of equations involving two ordinary differential equations. The values of all the dependent variables in the current sheet are computed from these equations as a function of distance in the streamwise direction. It is found that this model will admit as solutions finite strength current sheets. (Author)