Electron Temperature Inversion by Stimulated Brillouin Scattering During Electron Gyroharmonic Heating at EISCAT

Abstract

This work reports a holistic experimental investigation of stimulated Brillouin scattering (SBS) features and electron temperature inversion near the third electron gyroharmonic 3<i>f</i>_ce using the European Incoherent Scatter (EISCAT) heating facility. The evolution of SBS features including spectral offset, width, and power varies asymmetrically near 3<i>f</i>_ce. The asymmetries among SBS, electron temperature, and high frequency-enhanced ion lines are clearly exhibited for pumping above <i>f</i>₀ ≥ 3<i>f</i>_ce. Electron temperature <i>T</i>_e at the resonance regime has been retrieved from the measured SBS spectra based on the wave matching theory. The inversion results by SBS are consistent with measurement by the EISCAT UHF incoherent scatter radar (ISR) at the resonance altitude. The comparison of electron temperature <i>T</i>_e and ion temperature <i>T</i>_i between SBS and ISR enlightens great potentials for developing realistic ionospheric diagnostic technique.