Theoretical Investigations of High-Current Discharges in Bounded Plasmas

Abstract

We shall consider a discharge in which the ohmic heating energy is emitted as radiation, i.e., the thermal and kinetic energies of a plasma are low compared with the energy stored in the source. The number of particles in the plasma N is assumed to be known and this is possible only when the plasma is separated by a narrow vacuum gap from the nonion-ized matter (discharge-chamber wall) and, consequently, the gasdynamic pressure of the plasma is balanced out by magnetic forces, i.e., when the plasma is in a steady state in vacuum under given external conditions. We shall consider a discharge in which a plasma is a coaxial layer surrounding a thin metal conductor, located on the cylinder axis and carrying a current J0 , directed opposite to the plasma current Jp. The steady state is governed entirely by three quantities: N, J0, and E, where the last one is the electric field applied to the plasma; the plasma current is approximately 2 J0. This system has been considered for a thermonuclear plasma [18] and it is of interest to us because the Z pinch and planar discharge are the limiting cases corresponding to J0=0 and J0=∞.