On Stabilizing Role of Parallel Inhomogeneous Flow on Low-frequency Space Fluctuations |
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Authors: | Sen S |
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Institution: | (1) Research School of Physical Sciences and Engineering, The Australian National University, Canberra, ACT, 0200, Australia and;(2) Department of Physics and Astrophysics, University of Delhi, Delhi, 110 007, India |
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Abstract: | A fundamental reality throughout the space plasma is the existence of magnetic field-aligned flows. It is usually believed
that the spatial transverse shear in the parallel flow destabilizes many low frequency oscillations and this may be the origin
of low frequency oscillations in the ionosphere (V. V. Gavrishchaka et al., 1998, Phys. Rev. Lett., 80, 728 and Phys. Rev. Lett.: 2000, 85, 4285). Here we show that this notion of destabilizing influence of the shear in the parallel flow can be changed altogether
if one takes the effect of the flow curvature (second spatial derivative) into account. The transverse curvature in the parallel
flow can overcome the destabilizing influence of the shear and can render the low frequency modes stable. It is shown that
unlike flow shear the effect of flow curvature is sign- and mode-dependent.
This revised version was published online in August 2006 with corrections to the Cover Date. |
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Keywords: | ballooning mode flow profile PVS instability RT instability |
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