Ion pickup by the intrinsic low-frequency Alfvén waves with a spectrum
Lu Quan-Ming(陆全明)a)b), Li Xing(李醒)c), and Dong Chuan-Fei(董川飞)a)
aSchool of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China; b State Key Laboratory of Space Weather, Chinese Academy of Sciences, Beijing 100080, China; cInstitute of Mathematical and Physical Sciences, Aberystwyth University, Aberystwyth, SY23 2BZ, UK
Abstract Ion pickup by a monochromatic low-frequency Alfvén wave, which propagates along the background magnetic field, has recently been investigated in a low beta plasma (Lu and Li 2007 Phys. Plasmas14 042303). In this paper, the monochromatic Alfvén wave is generalized to a spectrum of Alfvén 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.
Received: 22 September 2008
Revised: 19 October 2008
Accepted manuscript online:
Fund: Project supported by the National
Natural Science Foundation of China (Grants Nos 40725013 and
40674093) and Chinese Academy of Sciences (Grant No KJCX2-YW-N28
9140C08060507ZCZJ19).
Cite this article:
Lu Quan-Ming(陆全明), Li Xing(李醒), and Dong Chuan-Fei(董川飞) Ion pickup by the intrinsic low-frequency Alfvén waves with a spectrum 2009 Chin. Phys. B 18 2101
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