Electron Energy Loss at Collision in Current-maintained Plasmas

Abstract

In an important class of laboratory plasmas, the plasma is maintained in existence by the passage of a steady direct current through it. Energy taken from the electric field which drives the current maintains the ionization in the plasma against losses of charged particles by diffusion or recombination. This energy is initially supplied chiefly to the electrons, which can drift rapidly in the field, and the majority of it is ultimately transferred to the heavy plasma particles by means of electron-heavy-particle interactions. In the steady state the energy input to the plasma from the field is balanced by the energy lost from the plasma by various means, including radiation, thermal conduction and the diffusive transport of ionization, excitation, and dissociation energy. Such current-maintained plasmas may exist under a very wide range of conditions with variations of the order of ten decades each in pressure, current density, and ionization density.