ABSTRACT
In a magnetic field when a net current flows through die inhomogeneity, the character of the evolution is much more diverse and complicated than for B - 0 . First of all, in a magnetic field ambipolar mobility exists in the ID problem even in the pure plasma. In the multidimensional case the perturbation of the pure plasma is split into several perturbations moving in different directions with different velocities. The spreading of each plasmoid in die linear case is determined by the combination of die diffusion process and the evolution in the self-consistent electric field generated by the net current For the nonlinear evolution the overturn of the density profile, formation of the shocks and the nonlinear deformation are typical. In the presence of ions of different species the character of evolution becomes far more diverse and interesting.
