Effects of inelastic collisions upon electrical conductivity and electron heating in the lower ionosphere

Abstract

A detailed investigation of the theory describing the electromagnetic perturbation of a weakly ionized plasma such as the atmospheric D region demonstrates the existence of a generalized momentum transfer cross section for the drift velocity which reduces to the ordinary momentum transfer cross section for elastic processes. However, the drift velocity in the case of air is still determined only by the elastic momentum transfer cross section, since the inelastic differential cross sections are small. It is also shown how inelastic collisions of electrons determine the electron cooling law, and a new result describing the way the average electron loses energy is established. It is a generalization of the approximate description always employed in cross‐modulation experiments. Apart from the assumption of a Maxwellian velocity distribution for the electrons this new result is exact, and it is shown how the mean energy loss per collision is related to the energy‐dependent excitation cross section. In the case of nitrogen molecules the effective energy relaxation time, (Gv)−1, varies as the square root of the electron temperature. This result is applied to show how a dielectric discontinuity or electromagnetic mirror may be induced in the D layer by ground‐based high‐powered transmitters.

Numerical simulation of ionospheric wave interaction experiments.

“…In (4) and (5), G is usually treated as a constant equal to about _3 10 , although various forms for the energy dependence of the loss term have been considered in order to account for inelastic collisions [Huxley, 1953;Altshuler, 1963;Benson, 1964]. The energy gain term, e, is obtained by calculating the disturbing wave energy absorbed at each height, per electron, per mean free time:…”

“…06 e. v. ). Various other forms for the loss term in (4) have been proposed [Huxley, 1953;Altshuler, 1963], but it appears that these can be accounted for by just letting G = G(Q) as is done here. Figure 6 shows the collision frequency and heating time constant profiles resulting from these atmospheric parameters.…”

Conference on Non-linear Processes in the Ionosphere, December 16-17, 1963. Volume 5

“…In the example previously discussed, if we were exciting 100 rayleighs of the 5577 A line we would expect electrons to attach at a rate of 3^p er second. The electrons would effectively disappear at this rate until they are re-released either by collisional detachment or by the reverse of process (8) . These rates are not well known and it might be that an ionospheric experiment would be one of the best with which to determine their rates.…”