Cusp altitudinal electron temperature gradient - Dynamics Explorer 2 implications for heating mechanisms

Curtis et al. (1982) have shown that the levels of wave turbulence observed by Dynamics Explorer 2 (DE 2) are too low by several orders of magnitude to explain the high temperatures of the polar cusp ionosphere in terms of local deposition of energy. The low altitude plasma instrument (LAPI) showed high levels of superthermal electron fluxes. The present investigation has the objective to examine the arising questions more quantitatively by using the DE 2 electron temperature and superthermal electron flux measurements. It is shown that on the basis of DE 2 observations in the polar cusp, a consistent picture can be drawn regarding the ionospheric electron heating process. It is pointed out that the heating involves the generation of plasma waves by field-aligned electron beams of magnetosheath origin.