Ion pickup by intrinsic low-frequency Alfvén waves with a spectrum  

作　　者：陆全明 李醒 董川飞 

机构地区：[1]School of Earth and Space Sciences,University of Science and Technology of China [2]State Key Laboratory of Space Weather,Chinese Academy of Sciences [3]Institute of Mathematical and Physical Sciences,Aberystwyth University,Aberystwyth,SY23 2BZ,UK

出　　处：《Chinese Physics B》2009年第5期2101-2108,共8页中国物理B（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grants Nos 40725013 and 40674093);Chinese Academy of Sciences(Grant No KJCX2-YW-N28 9140C08060507ZCZJ19)

摘　　要：Ion pickup by a monochromatic low-frequency Alfv6n wave, which propagates along the background magnetic field, has recently been investigated in a low beta plasma （Lu and Li 2007 Phys. Plasmas 14 042303）. In this paper, the monochromatic Alfven wave is generalized to a spectrum of Alfven waves with random phase. It finds that the process of ion pickup can be divided into two stages. First, ions are picked up in the transverse direction, and then phase difference （randomization） between ions due to their different parallel thermal motions leads to heating of the ions. The heating is dominant in the direction perpendicular to the background magnetic field. The temperatures of the ions at the asymptotic stage do not depend on individual waves in the spectrum, but are determined by the total amplitude of the waves. The effect of the initial ion bulk flow in the parallel direction on the heating is also considered in this paper.Ion pickup by a monochromatic low-frequency Alfv6n wave, which propagates along the background magnetic field, has recently been investigated in a low beta plasma （Lu and Li 2007 Phys. Plasmas 14 042303）. In this paper, the monochromatic Alfven wave is generalized to a spectrum of Alfven waves with random phase. It finds that the process of ion pickup can be divided into two stages. First, ions are picked up in the transverse direction, and then phase difference （randomization） between ions due to their different parallel thermal motions leads to heating of the ions. The heating is dominant in the direction perpendicular to the background magnetic field. The temperatures of the ions at the asymptotic stage do not depend on individual waves in the spectrum, but are determined by the total amplitude of the waves. The effect of the initial ion bulk flow in the parallel direction on the heating is also considered in this paper.

关 键 词：ion pickup Alfven wave ion heating temperature anisotropy 

分 类 号：O534[理学—等离子体物理]