Fast magnetic field penetration into a magnetized plasma with nonuniform density: A new family of shock solutions

Fast magnetic field-penetration into almost collisionless plasmas occurs through two previously studied mechanisms. The magnetic field can penetrate as a shock wave, into plasmas of nonuniform density or in cases with magnetic field curvature. While the shock velocity is defined by the large Hall resistivity, the shock width depends on the collisional resistivity. Fast magnetic field penetration as a whistler wave occurs also into magnetized plasmas with a longitudinal field. The present study combines both mechanisms by considering a nonuniform density plasma and requiring that it is previously magnetized with longitudinal as well as transverse magnetic fields. It is shown that a new family of shock solutions exists where the shock width is unaffected by the collisional resistivity and a whistler shock precursor appears. Below some threshold for the longitudinal field (which depends on the collisional resistivity), the solution is as the previously studied shocks with no precursor, however, above this th...