The problem with the non-idealness of the MHD heliosheath

Abstract

When describing the plasma - field behaviour in the heliospheric interface the difficulty arises that classical MHD concepts are not fully applicable to this complicated multifluid interaction scenario. The classical MHD concept of ideally frozen-in magnetic fields is only strictly valid, if the magnetized medium is fully ionized. As is well known, however, the heliospheric medium represents a partially ionized plasma which contains neutral H-atom flows interacting with the ions via resonant charge exchange processes. Caused by this cross-interaction between the neutral and the ionized media additional non-classical currents are driven which induce additional magnetic fields. These latter fields can be shown to show the tendency to diffuse relative to the ion bulk motion. As we can show this non-classical diffusion is especially pronounced near plasma boundaries or shocks and there act in a way to dissolve the abruptness in the transition structure of the plasma properties. Here we give first estimates of these effects and point to a need to revise the classical MHD theory at its application to partially ionized media.