Comparative Study On Plasma Heating By LH And RH Low-Frequency Alfvén Waves Via Non-Resonant Interactions

Plasma heating by Alfven waves is an important research topic in space plasmas and fusion plasmas. Previous research shows that the effect of non-resonant interactions between ions and Alfven waves in low-beta plasmas can be negligible. But now, it is found that the non-resonant effects can not be negligible when the higher order nonlinear effect is taken into account.In this paper, the test particle method is used to simulate ion heating by Alfven waves via non-resonant interactions in low-P plasmas. The heating effect of left-hand (LH) polarized and right-hand (RH) polarized Alfven wave is studied comparatively. The results show that, the interactions between LH waves and ions are stronger than those between RH waves and ions for higher frequency Alfven waves. But the interactions between LH waves and ions are almost same as those between RH waves and ions for lower frequency Alfven waves. The kappa-distributed ion heating by a single LH and RH Alfven wave is alse studied, the results indcate that when the ? decreases, the ions in the perpendicular are not significantly heated, the temperature tends to isotropic and the heating effects of LH and RH waves tend to be the same. When the ? increases, the heating effects in perpendicular direction are improved significantly, temperature becomes anisotropy gradually and the ion temperature increases faster than that by the RH wave heating. When the?= ?, the heating effects are best and temperature anisotropy is the most obvious. The ions are obviously heated by two low-frequency Alfven waves in perpendicular direction and parallel direction via non-resonant interactions, and temperature is anisotropic. Phase difference makes heating effect vary sinusoidally with a small amplitude.The effect of plasma heating by LH and RH waves is affected by different frequencies and ion distribution for a single Alfven wave. For two Alfven waves, phase difference will affect heating effect. The studies indicate that The interactions between different polarized Alfven waves and ions are influenced by frequency, ion distribution and phase difference.