The equilibrium of a conducting body embedded in a flowing plasma

Abstract

A conducting body embedded in a magnetized plasma flow may interact with the medium in a variety of ways. Within a MHD description, it is well known that the currents induced within the satellite can be closed in the plasma by standing Alfvén waves attached to it. However, we show that such a simple model (when viewed in the massive satellite rest frame) cannot satisfy continuity of mass, momentum or energy fluxes. The imbalance is due to the neglect of other plasma disturbances, i.e., the fast and slow magnetosonic modes. In this paper we introduce a slow magnetosonic wake and find that a suitable solution can redress the balance demanded by continuity to a large extent. The full solution, including the fast magnetosonic wave, remains an outstanding problem. Our principal conclusion is that it is not possible for a conducting body to excite a purely Alfvénic disturbance; there must be other plasma waves present too.