Comparison of computational algorithms for simulating an electrospray plume with a n-body approach

Abstract

In order to better evaluate the trade-offs between different simulation options for an electrospray thruster plume, we have developed a multi-scale n-body code to compute the evolution of a single emitter electrospray plume in the pure ionic regime. The electrostatic force computations in the simulation are captured through the use of three different computational algorithms with various degrees of approximation. The results of the simulations for a simple test case are compared in terms of computational speed and accuracy. The test case utilizes a single operating point (323nA) for a stable meniscus solution for the ionic liquid EMI-BF4 firing in the positive pure ion mode. Complex species and probabilistic fragmentation processes are neglected. An overview is provided of the trade-off between accuracy and computational speed for the three algorithms in the context of simulating the electrostatic interactions between particles. For a large number of particles, the faster algorithms show a significant reduction in computational time while maintaining a high level of accuracy with a proper choice of tuning parameters.

Angular Properties of Ionic Liquid Electrospray Emitters

“…Forces between ions are resolved each timestep to propagate ions and ion clusters through the electric field. The ion-ion component of the electric field (Poisson) is computed using the Barnes-and-Hut approximation of Coulombic interactions [21] to reduce the computational effort [22]. This contribution of the electric field is added to the background field created by the extractor-tip geometry (Laplace).…”