Electrostatic plasma instabilities in the equatorial electrojet

Abstract

TWO Nike Apache rockets were launched with Langmuir probes and other aeronomy payloads from Thumba, India (dip≃0° 47′), on January 28, 1971. The first rocket was launched at 10.40 1ST and the second at 11.10 IST. During the flights large scale irregularities in electron density in the scale sizes 30 to 150 m and with amplitudes of about 10% were observed in the 87 to 98 km region. Small scale irregularities with scale sizes 1 to 15 m were also observed in this region though with much smaller amplitudes. These irregularities are similar to cross-field instabilities observed earlier and add support to the previous measurements carried out during evening and night hours1,2. Above 100 km, the amplitude of the large scale irregularities decreases whereas the amplitude of the small scale irregularities increases. In this communication we shall present only the results for the small scale irregularities.