Experimental Investigation of Electron Collection by Rectangular Cuboid Probes in a High-Speed Plasma

Abstract

This paper describes ground-based scaled plasma experiments that simulated picosatellite and femtosatellite electron collection in the low earth orbit (LEO) ionospheric plasma, capturing special characteristics of these small spacecraft, including their possible rectangular cuboid shape, size relative to the plasma Debye length and the electron thermal gyroradius, and orientation with respect to plasma flow and magnetic field. It was observed that enhancing magnetic field strength to an appropriately scaled value to approximate LEO decreased the electron saturation current. The current collection characteristics were also impacted by the orientation of the probes relative to the magnetic field and the direction of plasma flow. In the voltage range tested, a model used in previous studies to predict electron saturation current underestimated the measured probe currents by a factor of two or more. Semi-empirical models developed here to calculate electron saturation currents that were within 10% of the measured currents. This experimental analysis enhances our understanding of current collection by rectangular cuboid probes in high-speed plasmas.