Spacecraft Charging Due To Energetic Electrons and Ions at Geosynchronous Altitudes

Abstract Satellites and spacecraft are usually exposed to space plasma disturbances, which vary in time at Geosynchronous Earth Orbit (GEO), affecting the charging of spacecraft and weather on the Earth. The charging currents are often described by the current‐balance equation (CBE) containing the electron‐ion (incoming/outgoing) current density fluxes and their energy distributions. The power‐law q ‐distribution is the most generalized distribution that essentially characterizes more pronounced energy tails and can be reduced to standard Maxwellian distribution for q → 1. Using the equilibrium currents, the CBE is solved both analytically and numerically to study spacecraft charging within the framework of Whittaker function. It is found that energetic electron and ion‐induced currents significantly modify the charging phenomenon on the spacecraft's surface. Especially, ion‐induced currents result in the delay of negative charging at critical electron thermal energy and enhance the magnitude of the total normalized current. Apart from CuBe surface material, numerical analysis is also carried out for silver and Aluminum to determine the magnitude of total normalized current and onset of negative charging. The present findings are consistent with spacecraft charging at GEO altitudes around the Earth.