EXOSPHERIC ELECTRON TEMPERATURES FROM NOSE WHISTLER ATTENUATION

A recent conjecture by Scarf that the observed whistler cutoff arises from thermal broadening of the cyclotron resonance has been used to evaluate electron temperatures. In the original work, very crude data were analyzed with a modified dispersion relation based on the collisionless Boltzmann equation, and it was concluded that T ≃ (2.0 ± 1.0) × 105 °K at R/Re = 4, geocentric. This thermal analysis has now been applied to Pope's new whistler data using each of his assumed density variations and both one- and two-hop interpretations of the data. The most reasonable results for the effective density and temperature at R/Re ≃ (4–4.5) appear to be N ≃ (200–700) electrons/cm3 and T ≃ 2.5 × 105 °K.