Evolution of magnetohydrodynamic waves and acceleration of particles in a collision of two plasmas

Electron acceleration in magnetohydrodynamic waves produced by a collision of two high-temperature plasmas in an external magnetic field B0 is studied with particle simulations. First, possible particle motions that traverse multiple layers with alternating magnetic polarity are illustrated. Then, it is shown with one-dimensional, fully kinetic, relativistic, electromagnetic particle simulations that as a result of plasma collision, a large-amplitude Alfven wave packet can be formed behind a magnetosonic shock wave. In the wave packet with alternating magnetic polarity, some electrons exhibit orbits predicted by the physical considerations and are accelerated to high energies such that γ>100. It is thus found that the Alfven wave packet as well as the magnetosonic shock wave can create ultrarelativistic particles with its strong wave fields. (author)