Bibcode
Díaz, A. J.; Soler, R.; Ballester, J. L.; Goossens, M.
Referencia bibliográfica
Highlights of Spanish Astrophysics VII, Proceedings of the X Scientific Meeting of the Spanish Astronomical Society (SEA), held in Valencia, July 9 - 13, 2012, Eds.: J.C. Guirado, L.M. Lara, V. Quilis, and J. Gorgas., pp.776-781
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5
2013
Número de citas
0
Número de citas referidas
0
Descripción
We study the modification of the classical criterion for the linear
onset and growing rate of the Kelvin-Helmholtz Instability (KHI) and the
Rayleigh-Taylor instability (RTI) in a partially ionised plasma in the
two-fluid description. The plasma is composed of a neutral fluid and an
electron-ion fluid, coupled by means of particle collisions. The
governing linear equations and appropriate boundary conditions,
including gravitational terms, are derived and applied to the case a
single interface between two partially ionised plasmas. For high
collision frequencies and low density contrasts the KHI is present for
super-Alfvénic velocity shear only. For high density contrasts
the threshold velocity shear can be reduced to sub-Alfvénic
values. For the particular case of turbulent plumes in prominences, we
conclude that sub-Alfvénic flow velocities can trigger the KHI
thanks to the ion-neutral coupling, but with long time scales.
Ion-neutral collisions have a strong impact on the RTI growth rate,
which can be decreased by an order of magnitude compared to the value in
the collisionless case. The time scale for the development of the
instability is much longer than in the classical incompressible fully
ionised case. This result may explain the existence of prominence fine
structures with life times of the order of 30 minutes.