Investigating the Chemical Stability of Electrospray Plumes During Particle Collisions

Abstract

Electrospray thrusters fulfill the main propulsion requirements for long-term small-satellite missions. However, the molecules present in the plume are susceptible to collisions, chemical reactions, and fragmentation, which may introduce different new species with various mass-to-charge ratios inside the plume. Prediction of the byproducts that appear upon collisions is of prime importance to predicting the evolution of the plume and estimating the performance and the lifetime expectancy of the thruster. In this work, we use molecular dynamics simulations to investigate monomer–neutral collisions at different impact configurations, impact energies, and impact parameters, and we provide the mass spectra of the resulting species. We predict that 1) collisions within a center-of-mass distance of 6 Å can result in momentum exchange and molecular fragmentation, 2) higher-energy impacts produce more byproducts, and 3) heavy molecules (e.g., 1-ethyl-3-methylimidazolium [EMI] and [Formula: see text]) are more likely to result from weak collisions ([Formula: see text]), whereas light molecules (e.g., H, F, and [Formula: see text]) are more likely to result from strong collisions. Collisional fragmentation is shown to negatively affect key performance indicators, including reductions in thrust, specific impulse, and propulsive efficiency. This phenomenon potentially accounts for the observed discrepancies in experimental measurements of current and mass loss rates.