Kinetic Simulations/Modeling of Plasma Sails

The viability of the plasma sail as a propulsion mechanism hinges on a number of issues that are as yet undetermined. Here we address two of these issues. One is in regards to the possibility of momentum transfer from the solar wind to the spacecraft and the other concerns the effect of the required plasma injection in the resulting magnetosphere. Previous two-fluid modeling of the plasma sail have been useful but given the predominance of ion kinetic effects, kinetic simulations are required in order to fully address the feasibility issues. Accordingly we have performed kinetic simulations of the plasma sail, using specially developed codes. We show that the interaction of the solar wind with the plasma sail forms a magnetosphere more akin to that of an asteroid and is much different than that of the Earth’s magnetosphere. This has significant implications for the feasibility of plasma sail. For instance, although ion reflection does occur, it is not clear how momentum is transferred to the spacecraft because the reflection is from the bow wave and not the magnetopause. Further we find that both the plasma transfer as well as the expansion of the bubble are sensitive to the details of the plasma injection. Thus Specification of the appropriate plasma injection scheme remains to be established.