Detalles de publicación
PP 012019
Rayleigh-Taylor instability in partially ionized compressible plasmas
(1) Instituto de Astrofísica de Canarias, Tenerife, Spain
(2) Departamento de Astrofísica, Universidad de la Laguna, Tenerife, Spain
(3) Centre for Plasma Astrophysics, Department of Mathematics, KU Leuven, Belgium
(4) Universitat de les Illes Balears, Palma de Mallorca, Spain
We study the modification of the classical criterion for the linear onset
and growing rate of the Rayleigh-Taylor instability (RTI) in a partially ionized
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 of the RTI in a single
interface between two partially ionized plasmas.
The limits of collisionless, no gravity and incompressible fluids are checked
before addressing the general case. We find that both compressibility and
ion-neutral collisions lower the linear growth rate, but do not affect the
critical threshold of the onset of the RTI. The configuration is always unstable
when a lighter plasma is below a heavier plasma regardless the value of the
magnetic field strength, the ionization degree and the ion-neutral collision
frequency. However, 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.
Ion-neutral collisions are necessary to accurately describe the evolution of the
RTI in partially ionized plasmas such as prominences. The time scale for the
development of the instability is much longer than in the classical
incompressible fully ionized case. This result may explain the existence of
prominence fine structures with life times of the order of 30 minutes. The time
scales derived from the classical theory are about one order of magnitude
shorter and incompatible with the observed life times.
and growing rate of the Rayleigh-Taylor instability (RTI) in a partially ionized
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 of the RTI in a single
interface between two partially ionized plasmas.
The limits of collisionless, no gravity and incompressible fluids are checked
before addressing the general case. We find that both compressibility and
ion-neutral collisions lower the linear growth rate, but do not affect the
critical threshold of the onset of the RTI. The configuration is always unstable
when a lighter plasma is below a heavier plasma regardless the value of the
magnetic field strength, the ionization degree and the ion-neutral collision
frequency. However, 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.
Ion-neutral collisions are necessary to accurately describe the evolution of the
RTI in partially ionized plasmas such as prominences. The time scale for the
development of the instability is much longer than in the classical
incompressible fully ionized case. This result may explain the existence of
prominence fine structures with life times of the order of 30 minutes. The time
scales derived from the classical theory are about one order of magnitude
shorter and incompatible with the observed life times.