PLASMA-WAVES IN THE SHEATH OF THE TSS-1R SATELLITE

The current flow in the Tethered Satellite System (TSS) induces a stro ng excitation of electric and magnetic fluctuations in the potential s heath surrounding the subsatellite. The wave sensors of the experiment RETE (Research on Electrodynamic Tether Effects) have measured power spectra of electromagnetic fields from 180 Hz to 12 MHz, providing inf ormation on the physical processes taking place around highly charged bodies in the ionosphere and, in particular, the role of wave-particle interactions and anomalous collisionality. We report on the observati ons during three events of almost steady current flow at 50, 190 and 5 5 mA, taking place at positive satellite potentials of about 9, 200 an d 2 V. The largest power spectral density occurs at frequencies betwee n 2 and 4 kHz, close to the lower hybrid frequency, where electric fie ld fluctuations up to 12 V/m have been observed. In this frequency ban d the fields are electrostatic and radially polarized, with a marked r am-wake signature.