Suprathermal electrons observed on the TSS-1R satellite

Particle measurements up to 27,000 eV were made on the TSS-1R (Tethered Satellite System) satellite. The TSS satellite developed a positive bias due to the Lorentz force. It was the intent that electron measurements on the TSS satellite could be used to track the spacecraft potential and collected current. What was observed was quite different. Accelerated ionospheric electrons were observed to only ∼70 eV even though larger spacecraft potentials were observed by other diagnostics on the TSS satellite. When observed they agreed with these independent measurements of the potential. In addition to the anticipated accelerated thermals, a suprathermal population of electrons was observed to be centered around 200 eV. This population exhibited a 4 orders-of-magnitude increase in intensity as the spacecraft potential exceeded the O+ ram energy. The disappearance of the accelerated thermals is explained by the observation that the suprathermal flux becomes larger in magnitude, thus hiding the thermals. However the suprathermals cannot be the dominant current carriers if they are the result of a DC process as their calculated current magnitude exceeds that observed. These results are best explained if one assumes an AC acceleration of the suprathermal electrons whose free energy is derived from the differential equation image drift between electrons and ions.