The Motion of Ionized Gas in Combined Magnetic, Electric and Mechanical Fields of Force

Abstract

Transient electric and mechanical forces uniform in space are applied to a gas in the presence of a steady magnetic field. The current transport equation for the anisotropically conducting medium is used to determine the subsequent motion of the gas, the internal electric field and the current density. These are damped oscillatory functions leading to a steady state. There is a close connection between the effects of the electric and mechanical forces : a steady internal electric field perpendicular to the magnetic field cannot exist unless accompanied by a mechanical force. The relationship between the two is examined. Neglect of this relationship has already proved fatal to many astrophysical theories. On the other hand, there seems little justification for treating mechanical forces as “ equivalent electric fields ”, as is often done. This and a companion paper appear to provide, for the first time, a satisfactory system for using transport equations in the study of dynamical problems in nearly uniform, anisotropically conducting gases. Such problems are proving increasingly numerous and important in astrophysics.