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Measurement of low-energy electrons in the day airglow and day side auroral zone from Atmosphere Explorer C

1975; American Geophysical Union; Volume: 80; Issue: 28 Linguagem: Inglês

10.1029/ja080i028p03934

2156-2202

J. P. Doering, W. K. Peterson, C. O. Bostrom, Jerawan Armstrong,

Solar and Space Plasma Dynamics

The photoelectron spectrometer experiment on Atmosphere Explorer C has obtained high-resolution spectra of the energy distribution of 2- to 500-eV electrons in the thermosphere at altitudes above 155 km. The photoelectron spectrum in the day airglow has been measured in detail over a wide range of altitude, latitude, and local time. Structure observed near 27 eV is assigned to photoelectrons ejected from atomic oxygen by the intense solar He II (304 Å) radiation. The photoelectron energy distribution is shown to have a sharp cutoff near 60 eV. In addition to the day airglow data, spectra are also presented showing low-energy (100–500 eV) electron precipitation near the polar boundary of the auroral oval at magnetic local times near 0830. The precipitation is a low-energy inverted ‘V’ type event occurring over an extremely narrow range of invariant latitude (ΔΛ ∼ 0.3°). The electron stream is about 50 eV wide at the half-maximum intensity points and changes in energy from 100 to 500 eV. Instrument calibration in the laboratory, performance of the experiment in orbit, and plans for further analysis of the large body of data which now exists are discussed in detail.