A new facet of the heating of ambient electrons by energetic charged particle streams

Abstract

An energetic charged particle flux must often be accompanied by a reverse current of the same magnitude at the same place. In the ionosphere the joule dissipation of such a reverse current heats the electron gas more than the direct coulomb collisions of the energetic particles with the ambient electrons provided FE/ φ ≳ 3.5 × 10 3 n e 2 v e −1 eV cm −2 sec −1, where E is the average energy (in eV) of particles in the flux ( F), and φ is a factor equal to or greater than 1, depending on whether or not all the energetic particles are moving in one direction only. For fluxes in which φ = 1, the condition is satisfied by F values > 3 × 10 10 eV cm −2 sec −1 in and below the E-region and by values > 4 × 10 12 eV cm −2 sec −1 in the F-region. The rise in electron temperature that is caused by this indirect joule dissipation when heat conduction in the ambient electrons is small is estimated, with special reference to auroral bombardment.