Propulsion Properties of Electric Sails

Multiparametric study of a thrust force exerted on a model electric (E) sail spacecraft by the solar wind is conducted with a particle-in-cell method. Several effects relevant to the thrust performance are examined with the focus on the accuracy of the obtained results, reflected in the improved initial conditions and physically realistic boundary conditions set at the external boundaries and the near field of a tether. These effects include thrust sensitivity to the solar wind density, temperature, and relative velocity between the solar wind and the spacecraft as well as the influence of the tether potential on the resulting thrust force. The dependence of thrust [Formula: see text] on the distance between the spacecraft and the sun [Formula: see text] is found to have an exponential form approximated by [Formula: see text]. Numerical estimates of the electric current to the E-sail tether mesh give values that are on average about 50% higher than those predicted by the orbital motion limited theory. In addition to single tethers, tether arrays are also studied and shown to have lower thrust per tether that that of a single tether.