Ion temperature anisotropy due to perpendicular heating by Alfven wave propagating along magnetic field lines

Abstract

The perpendicular heating and acceleration of ions by linearly polarized Alfven wave, which is propagating along constant background magnetic field, is studied. The perpendicular diffusion coefficient of ions is calculated through the autocorrelation function based on linear perturbation theory, which unambiguously demonstrates that ion heating is attained by non-resonant wave-particle interaction. It is found that the perpendicular heating and acceleration of ions occur by the Alfven wave during a relatively short time interval, i.e., approximately 20 ion gyro period (Omega(i0)t) even though the perturbation amplitude is quite low. Also, it is shown that the temperature anisotropy of ions A, where A = T-perpendicular to/T-parallel to - 1; increases with the increasing perturbation amplitude while the parallel ion heating does not occur. Test particle simulation is also carried out in order to investigate the non-resonant perpendicular heating process. Published by AIP Publishing