E-region electron temperature measurements: a review

Abstract

The two major techniques for the E-region electron temperature measurements, namely, the Langmuir probe flown on rockets and the ground based incoherent-scatter radar, are discussed and results of the available measurements presented. While the radar measurements show the electron temperature to be very nearly equal to the neutral temperature at heights below 130 km, the Langmuir probes, in general, show electrons to be much hotter than neutrals for these heights. The radar measurements, however, are in agreement with theoretical studies of thermal balance in the Eregion with euv as the only heat source. The Langmuir probe measurements, on the other hand, can only be explained if heat sources, in addition to the solar euv radiation, also exist. The surface contamination on Langmuir probe, coupled with low plasma density, can produce work function drift and consequently distort the current-voltage characteristic, resulting in erroneous electron temperature values in the E-region.