Spacecraft Charging in Non-Maxwellian Plasmas at GEO Altitudes

Abstract

Spacecraft charging phenomenon at GEO altitudes is revisited by highlighting various spacecraft missions, spacecraft orbits, surface charge mitigating techniques, and particle distribution models. A comparative analysis is presented to study the onset of negative charging for spacecraft with single Maxwellian, Kappa, and q-nonextensive distributions. Since the plasma constitutes a mixture of two clouds having cold and hot electrons with their distinct thermal energies and densities, therefore it is important to investigate surface charging with double extensive and non-extensive distributions as well as analyzing the current-balance equations (CBEs) both analytically and numerically. The Whittaker function integral is employed to solve the power-law integrals. The q-distributed electrons show more pronounced energy tails to obey Tsallis statistics having nonstationary equilibrium states. Non-extensivity effect strongly modifies the CBE for spacecraft charging, supporting better in the limit q<1 in contrast to Maxwell and κ distributions. Numerically critical and anticritical thresholds are also identified to understand the onset of negative charging of various space-grade materials.