A model for precursor structure in supercritical perpendicular, collisionless shock waves

Abstract

Magnetosonic solitons may be given smooth increasing profiles by assuming the presence within the wave of a current distribution Jy(x) of trapped ions perpendicular to Bz(x) and the wave velocity Vx. Suitable ions are found immediately upstream of perpendicular, collisionless shock waves and these are coincident with the often observed ‘foot’ in magnetic field profiles of moderately supercritical shocks. By modelling Jy(x) we apply the theory to previous experiments where Jy(x) is observed, and are able to reproduce reasonably, and thus explain, the profiles in the foot. Insight into a number of features of fast shocks is obtained.