Unsteady Simulations of Rocket Plume Expansions in Geostationary Earth Orbit

Abstract

Unsteady, direct simulation Monte Carlo (DSMC)-particle-in-cell (PIC) simulations of rocket plume expansions into the magnetosphere at geostationary Earth orbit (GEO) are presented for three rocket thruster pulse durations: 0.1 s, 1.4 s, and 9.9 s. The chemical rocket thruster ejects hydrazine combustion products at a mass flow rate of 4.5 × 10 −4 kg/s, and the number densities are computed as a function of time for distances up to 35 km from the rocket thruster. The plume reaches steady-state operation 1 km downstream of the rocket thruster before the thruster is shut off at 1.4 s, and steady-state operation is reached as far as 20 km downstream of the rocket thruster for the 9.9 s pulse duration. An analytic expression for free-molecular flow expanding into a vacuum is compared to the unsteady simulations for number densities, and the influences of energetic protons and electrons emitted from the Sun on predicted total number densities are investigated.