Distortions of the energy distribution of ionospheric thermal electrons near the focus of Sq current vortex

Energy distributions of the thermal electrons in the ionospheric plasma were measured on 16 January 1974 and 16 September 1976 by two Japanese rockets, K-9M-45 and K-9M-55 respectively near the focus of S_q current vortex. The main effort was to investigate the energy state of the thermal electrons in a localized hot electron layer which occurs at a height of around 105 km in winter.The results obtained on 16 January 1974 showed that the thermal electrons in the hot electron layer had not a pure Maxwell distribution. While on 16 September 1976, the energy distribution of the electrons was found to be almost Maxwellian in the dynamo region as well as the F-region.