Propagation of the Alfvén Wave and Induced Perturbations in the Vicinity of a 3D Proper Magnetic Null Point

Abstract

Abstract The aim of the present work is to study the propagation of the Alfvén wave around a 3D proper magnetic null point and its accompanying perturbations. In this line, the shock-capturing Godunov-type PLUTO code is used to solve the magnetohydrodynamic (MHD) equations. It is found that the Alfvén wave propagates toward the null point at the fan plane and the wave−wave interaction could be the main reason for the Alfvén wave energy dissipation, ehile, at two other planes including the spine axis, the Alfvén wave spreads toward the spine axis and accumulates along it. Furthermore, the fast magnetoacoustic wave moves toward the null point at the fan plane and also at two other planes including the spine axis. The fast magnetoacoustic wave also refracts around the null point without any significant accumulation along the spine axis. Finally, the slow mode moves toward the null point at the fan plane. It is illustrated that, at the x,z plane, in addition to the refraction of the slow wave around the null point, there is an accumulation of the slow mode along the spine axis, while, at the other plane including the spine axis, the slow magnetoacoustic wave refracts around the null point. Moreover, it is found that the 3D structure results in the high amplitude of MHD wave energy in comparison with the 2.5D structure. Finally, it is found that the Alfvén wave gives its energy to the induced fast and slow magnetoacoustic waves and they have more time to heat the plasma.