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Umeki & Terasawa 1992
Umeki, H. and Terasawa, T. (1992). Decay instability of incoherent Alfvén waves in solar wind. Journal of Geophysical Research 97: doi: 10.1029/91JA02967. issn: 0148-0227.

The nonlinear evolution of a large-amplitude incoherent Alfv¿n wave is studied via one-dimensional magnetohydrodynamic simulation. The initial wave magnetic field is given as a superposition of circularly polarized Alfv¿n waves with the same helicity and propagation direction but with different wave numbers. What we observe is contrary to the previous belief that incoherent Alfv¿n waves are stable against decay: In a low &bgr; plasma (&bgr;=0.2) we can clearly see the growth of backscattered Alfv¿n waves, which are opposite in helicity and propagation direction from the original Alfv¿n waves. In a high &bgr; plasma (&bgr;=2.0), on the other hand, no backscattered Alfv¿n waves are observed. These results are consistent with the expectation from the theory of the parametric decay instability developed for a coherent Alfv¿n wave. We also show that incoherent Alfv¿n waves in the solar wind can decay parametrically in the region of 4--20 RS where &bgr; is sufficiently low. For the decay process to work, the period of Alfv¿n waves should be less than several minutes. ¿ American Geophysical Union 1992

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Abstract

Keywords
Space Plasma Physics, Numerical simulation studies, Space Plasma Physics, Waves and instabilities, Interplanetary Physics, Solar wind plasma, Interplanetary Physics, MHD waves and turbulence
Journal
Journal of Geophysical Research
http://www.agu.org/journals/jb/
Publisher
American Geophysical Union
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