A Wave Mechanical Approach to the Plasma Interaction Problems

Abstract

WHEN an object moves rapidly in an ionized gas, its surface, if electrically conducting, will become charged due to the differential in mobilities of the electrons and ions in the gas. Assuming that the medium is in thermodynamic equilibrium and consists of singly charged particles only, the surface will acquire a negative potential. The equilibrium surface potential will be reached when the incident fluxes of electrons and ions become equalized by the biased surface potential. A charged body influences, by electrostatic interaction, the trajectories and concentrations of the neighbouring charged particles which, in turn, modify the potential field by their presence as space charges. This electrodynamic phenomenon, which occurs in the immediate vicinity of a body moving rapidly in a rarefied ionized medium, is the plasma interaction of interest. A variety of scientific experiments have led to the discussion of this problem. As an example we may cite the measurement of the upper ionosphere by the use of a satellite probing scheme. The ionospheric quantities of interest, for example, electron density and temperature, must be inferred from the planned measurements made at the satellite body which is, of course, shielded by a cloud of charged particles and their associated potential field. The theory of measurement, therefore, must be based on an understanding of the specific plasma interaction developed.