Current state-of-the-art for the measurement of non-Maxwellian plasma parameters with the EISCAT UHF Facility

• Published in: Annales Geophysicae
• Main Authors: D. Hubert, F. Leblanc, P. Gaimard
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 1996
• Subjects: Science; Q; Physics; QC1-999; Geophysics. Cosmic physics; QC801-809; EISCAT
• Online Access: https://doi.org/10.1007/s00585-996-1506-4; https://doaj.org/article/5f1603230e074747accaf489a2151803

New results on the information that can be extracted from simulated non-Maxwellian incoherent radar spectra are presented. The cases of a pure ionosphere and of a composite ionosphere typical of a given altitude of the auroral F region are considered. In the case of a pure ionosphere of NO + or O + ions it has been shown that the electron temperature and the electron density can be derived from a Maxwellian analysis of radar spectra measured at aspect angles of 0° or 21° respectively; the ion temperature and ion temperature anisotropy can be derived from a non- constraining model such as the 1D Raman fitting of a complementary measurement made at an aspect angle larger than 0° for the NO + ions, or at an aspect angle larger than 21° for the O + ions. Moreover with such measurements at large aspect angles, the shape of the velocity ion distribution functions can simultaneously be inferred. The case of a composite ionosphere of atomic O + and molecular NO + ions is a difficult challenge which requires simultaneously a complementary measurement of the electron temperature to provide the ion composition and the electron density from the incoherent radar spectra at a specific aspect angle of 21°; hence, a model dependent routine is necessary to derive the ion temperatures and ion temperature anisotropies. In the case where the electron temperature is not given, a routine which depends on ion distribution models is required first: the better the ion distribution models are, the more accurately derived the plasma parameters will be. In both cases of a composite ionosphere, the 1D Raman fitting can be used to keep a check on the validity of the results provided by the ion distribution model dependent routine.