The boundary layer between a cold plasma and a confined magnetic field when the plasma is not normally incident on the boundary

Abstract

In this paper, we consider in greater detail than hitherto (Parker, 1967) the effect of a transverse plasma velocity component on the structure of the boundary layer between a plasma and a vacuum magnetic field. The exact equations of the problem, taking into account the electrostatic field arising from charge separation in the boundary, are solved numerically. It is shown that the additional magnetic field, produced by the transverse velocity component, depends critically on the degree of neutralisation and that this field is very small compared with the vacuum magnetic field unless the boundary layers are neutralised to a high degree by the presence of a background plasma. When the electrostatic field is completely neutralised, the magnetic field component due to the transverse component of velocity is dominant, even for comparatively low transverse velocities. Moreover, for this model, the new component of the magnetic field does not vanish at the stream front and (in the case of complete neutralisation) its direction is such as to confine the plasma. The results are discussed in connection with the magnetopause.