Observations of Precipitating Electrons by Cylindrical Electrostatic Analyzers on Board the Japanese Antarctic Sounding Rockets S-310JA-1 and 2 (e. Event Session) (Proceedings of the Second Symposium on Coordinated Observations of the Ionosphere and the Magnetosphere in the Polar Regions : Part II)

Abstract

Cylindrical electrostatic analyzers on board the Japanese Antarctic sounding rockets S-310JA-1 and S-310JA-2 launched on February 13, 1976 and on February 10, 1977, respectively, at Syowa Station, measured the energy spectra of energetic electrons in the Antarctic polar ionosphere. At the time of the former flight, the geomagnetic activity was low, and the electron flux of about 10^3 electrons/cm^2 sec・str・eV was obtained at an energy of 5 keV. The altitude dependence of the flux of 2 keV electrons showed the maximum flux near 150 km altitude of the descending path. This implies that there was a local electron precipitation region. At the time of the latter flight, the geomagnetic activity was high and there was a diffuse aurora at the time of launch. The measured electron flux was about 1.8×10^3 electrons/ cm^2・sec・str・eV at the energy of 4.2 keV and about 2.3×10^4 electrons/cm^2・sec・str・ev at 740 eV. The electron whose energy was in the neighborhood of 500 eV had a considerable pitch angle dependence, and the field aligned current density due to these electrons was estimated to be about 1.47×10^A/m^2.