Energy distribution of thermal electrons at the height of lower-E-region

Energy distributions of thermal electrons (0.2 - 1 eV) were measured in the lower E region from the height of 90 Km. The distributions of the electrons started deviating from Maxwellian distributions at the height of ∼104 Km. The distortion becomes most intense at the height of 107 Km and the electron population apparently consists of two groups at different electron temperatures in addition to excess high energy tail. The distortion almost vanished at the height of ∼130 Km, again increased at ∼150 Km and finally faded out at the height of ∼210 Km. We suggest that both high electron temperature and excess high energy tail are locally generated by some ionospheric-current related mechanism.