Thrust Evaluation of Small-Scale Magnetic Sail Spacecraft by Three-Dimensional Particle-in-Cell Simulation

A magnetic sail is a spacecraft propulsion system that generates an artificial magnetosphere to block solar wind particles and uses the imparted momentum to accelerate a spacecraft. In the present study, three-dimensional particle-in-cell simulations were conducted on small-scale magnetospheres to investigate the thrust characteristics of small-scale magnetic sails. The results show that electron Larmor motion and charge separation become significant in small-scale magnetospheres, and that the thrust of the magnetic sail is affected by the cross-sectional area of the charge-separated plasma cavity. Empirical formulas for the thrust are obtained by changing spacecraft design and solar wind parameters. These equations show that the thrust of a small-scale magnetic sail is approximately proportional to magnetic moment, solar wind density, and solar wind velocity. The empirical formulas enable determination of the trajectory of the spacecraft and performance of a mission analysis.