Propagation of KdV Solitons in a Magnetised Plasma Column

We investigate the nature of the solitons propagating along a magnetized plasma column. These solitons involve low Mach number irrotational and incompressible plasma motions. By regular perturbation analysis we identify them unambiguously as KdV solitons and give the conditions for them to be of the rarefactive or compressive type and for their speed to become super-Alfvenic. Numerical simulations of the full 2D, compressible MHD equations support the irrotational and icompressible assumptions and reproduce the solitons' properties in excellent agreement with the perturbation analysis