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

This work reports a holistic experimental investigation of stimulated Brillouin scattering (SBS) features and electron temperature inversion near the third electron gyroharmonic 3fce using the European Incoherent Scatter (EISCAT) heating facility. The evolution of SBS features including spectral offset, width, and power varies asymmetrically near 3fce. The asymmetries among SBS, electron temperature, and high frequency‐enhanced ion lines are clearly exhibited for pumping above f0 ≥ 3fce. Electron temperature Te 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 Te and ion temperature Ti between SBS and ISR enlightens great potentials for developing realistic ionospheric diagnostic technique. Key Points Clearly, SBS dynamics and spectral features are characterized near third electron gyroharmonics at EISCAT Qualitative comparison of electron temperature inversion based on SBS agrees with ISR measurement The asymmetries of SBS and DM are closely correlated with enhanced ion lines and electron temperature near 3fce