Resonant heating of the ionospheric plasma by powerful radiopulses aboard the Intercosmos-19 and Cosmos-1809 satellites

Local heating/acceleration of the ionospheric plasma particles near the satellite by RF pulses of the powerful topside sounder transmitter was detected by the soft electron spectrometer on board the Intercosmos-19 satellite and was first described in 1981 (Galperin et al., 1981, Cosmic Res.19, 22). The acceleration of the electrons occurs primarily perpendicular to the external magnetic field for 0.3-3 ms. The energy spectrum of the accelerated electrons is close to Maxwellian with a mean temperature of the order of 100 eV. The electrons are accelerated at frequencies mainly near the first harmonics of the electron plasma and the gyrofrequency, but also in the frequency region of the plasma diffuse resonances and between the second and third harmonics of the plasma frequency. These investigations were continued on board the recent Cosmos-1809 satellite. Intensities of the sounder accelerated particles (SAP) were time- resolved on a millisecond scale. Different mechanisms of wave - particle interactions which could be responsible for SAP are discussed.