Heating of ions with a Kappa velocity distribution by a non-resonant Alfvén wave

In this study, the heating of ions with a Kappa (κ) velocity distribution by an Alfvén wave propagating along an external magnetic field via non-resonant wave–particle interactions in low-beta plasmas is investigated by means of both quasilinear theory and test-particle simulation. The κ velocity distribution is most suitable for describing a non-thermal distribution with an enhanced high-energy tail and includes the Boltzmann distribution as a limiting case. Because of the thermal non-equilibrium factor (κ factor), the heating effect of κ   ions is weaker than that of Boltzmann ions, and when κ→∞κ→∞, the heating effects become identical. It is determined that the ion pickup increases as the κ parameter increases, and the heating is dominant in the perpendicular (to the background magnetic field) direction. Subsequently, during the heating process, ions are also accelerated in the parallel direction. This phenomenon may have relevance to the heating of ions in the solar corona and to ion heating in some toroidal-confinement fusion devices.