Electron temperature evidence for nonthermal equilibrium in the ionosphere

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A review of the electrostatic probe experiment is given. The electron temperature and positive ion density data resulting from its use in two flights at Fort Churchill, Canada and in two flights at Wallops Island in midsummer 1960 and spring 1961, are discussed. The electron temperature profiles exhibit large positive gradients between 150 and 250 km, gradually changing to an approximately isothermal region (approximately 2800 deg K) above 250 km. An exception to this was the second Wallops Island measurement in which a negative temperature gradient was observed above 250 km, in a quiet ionosphere. The ion density profiles show only slight density maxima in the E region, the less distinct F/sub 1/ regions, and, at Wallops Island, well defined F/ maxima at about 300 kilometers. Electron density data from two-frequency beacon experiments flown on the same rockets, and simultaneously recorded ionograms are presented for comparison. Agreement is obtained between the electron density measured by the two different techniques and the ion density as measured by the dumbbell technique. It is concluded that the dumbbell experiment measures temperatures representative of all thermal electrons, if gas temperatures derived from satellite drag measurements and other techniques are valid as generally accepted,more » electrons and neutral particles are not in thermal equilibrium in the daytime ionosphere to altitudes of at least 420 km. Electron temperature varies significantly with the state of the ionosphere, electron temperatures being higher and more variable in the more disturbed ionospheres. (auth)« less