Kinetic Alfvén solitons in a low-beta plasma

摘要

Kinetic Alfvén solitons with hot electrons and finite electron inertia in a low-beta ([beta]=8[pi]n0T/B2G, the ratio of the kinetic to the magnetic pressure) plasma is studied analytically, with the ion motion being considered dominant through the polarization drift. Both compressive and rarefactive kinetic Alfvén solitons are found to exist within a definite range of kz (the direction of propagation of the kinetic Alfvén solitary waves with respect to the direction of the magnetic field) for each pair of assigned values of [beta] and M (Mach number). Unlike in previous theoretical investigations, [beta] appears as an explicit parameter for the kinetic Alfvén solitons in this case. In addition, consideration of the electron pressure gradient is found to suppress the speed of both the Alfvén solitons considerably for A (=2QM2/[beta]k2z, with Q the electron-to-ion mass ratio) less than unity.