Marco Velli

We investigate dispersive and kinetic effects on the evolution of a two-dimensional kinked Alfvén wave packet by comparing results from magnetohydrodynamic (MHD), Hall-MHD, and hybrid simulations of a low-β plasma. We find that the Hall term determines the overall evolution of the wave packet over a characteristic time τ*=τaℓ/di in both fluid and hybrid models. Dispersion of the wave packet leads to the conversion of the wave energy into internal plasma energy. When kinetic protons are considered, the proton internal energy increase has contributions from both plasma compressions and phase space mixing. The latter occurs in the direction parallel to the guiding mean magnetic field, due to protons resonating at the Alfvén speed with a compressible mode forced by the wave packet. Implications of our results for switchbacks observations and solar wind energetics are discussed.