Probe and radar electron temperatures in an isotropic nonequilibrium plasma

Abstract

Electron temperatures measured by electrostatic probes and radar backscatter are distinct physical quantities with the temperature from each technique determined from a different moment of the electron distribution function. Numerical inequality of temperatures results from a non-Maxwellian electron distribution function or equivalently, a non-equilibrium electron plasma. Probe and backscatter electron temperatures are studied for low and high energy (isotropic) distortions of the distribution function. The non-equilibrium plasma generally produces higher probe than backscatter temperatures, however the temperature difference is small for distortions due to realistic photoelectron fluxes. If large temperature differences occur in the ionosphere, both probe and backscatter temperatures would differ from the temperature characterizing the average electron kinetic energy, and a single temperature applicable to a variety of physical processes would no longer exist.