Effect of finite ion Larmor radius on the stability of rotating superposed fluids

1969 ◽  
Vol 47 (8) ◽  
pp. 831-834 ◽  
Author(s):  
G. L. Kalra
Keyword(s):  
Gravitational Instability ◽  
Equations Of Motion ◽  
Vortex Sheet ◽  
Larmor Radius ◽  
Simultaneous Presence ◽  
Uniform Rotation ◽  
Finite Larmor Radius ◽  
The Stability ◽  
Superposed Fluids ◽  
Macroscopic Equations

The effect of finite ion Larmor radius on the gravitational instability of two superposed fluids in uniform rotation is investigated for interchange perturbations, using the macroscopic equations of motion, where the finite ion Larmor radius effect is incorporated through off-diagonal terms in the pressure tensor. It is found that the region of stable wavelengths is enhanced due to the simultaneous presence of finite Larmor radius and a uniform rotation. A similar conclusion is also arrived at for the situation when a vortex sheet is present between the two superposed fluids.

EFFECT OF FINITE ION LARMOR RADIUS ON THE STABILITY OF SUPERPOSED FLUIDS

1967 ◽  
Vol 45 (4) ◽  
pp. 1579-1585 ◽  
Author(s):  
G. L. Kalra
Keyword(s):  
Magnetic Field ◽  
Vortex Sheet ◽  
Larmor Radius ◽  
General Direction ◽  
Ambient Magnetic Field ◽  
The Stability ◽  
Superposed Fluids

The effect of finite ion Larmor radius on the problem of stability of incompressible and infinitely conducting superposed fluids is investigated for a general direction of perturbation. It is found that whereas the interchange perturbations are stabilized in the presence of Larmor radius, the noninterchange perturbations (which affect the ambient magnetic field) lead to overstability due to Larmor radius effects in a configuration (unstable in the absence of magnetic field) stabilized by a strong enough magnetic field. The configuration which is monotonically unstable in the absence of Larmor radius now, in addition, exhibits overstable modes. Similar conclusions are obtained in the presence of vortex sheet as well.

Effect of Finite Larmor Radius on the Rayleigh-Taylor Instability of Two Component Magnetized Rotating Plasma

1998 ◽  
Vol 53 (12) ◽  
pp. 937-944 ◽  
Author(s):  
P. K. Sharma ◽  
R. K. Chhajlani
Keyword(s):  
Magnetic Field ◽  
Growth Rate ◽  
Normal Mode Analysis ◽  
Mode Analysis ◽  
Larmor Radius ◽  
Horizontal Magnetic Field ◽  
Finite Larmor Radius ◽  
Neutral Particles ◽  
Rayleigh Taylor Instability ◽  
Superposed Fluids

Abstract The Rayleigh-Taylor (R-T) instability of two superposed plasmas, consisting of interacting ions and neutrals, in a horizontal magnetic field is investigated. The usual magnetohydrodynamic equations, including the permeability of the medium, are modified for finite Larmor radius (FLR) corrections. From the relevant linearized perturbation equations, using normal mode analysis, the dispersion relation for the two superposed fluids of different densities is derived. This relation shows that the growth rate unstability is reduced due to FLR corrections, rotation and the presence of neutrals. The horizontal magnetic field plays no role in the R-T instability. The R-T instability is discussed for various simplified configurations. It remains unaffected by the permeability of the porous medium, presence of neutral particles and rotation. The effect of different factors on the growth rate of R-T instability is investigated using numerical analysis. Corresponding graphs are plotted for showing the effect of these factors on the growth of the R-T instability.

scholarly journals Ion Confinement in a Toroidal Heliac

1998 ◽  
Vol 51 (1) ◽  
pp. 67
Author(s):  
J. L. V. Lewandowski
Keyword(s):  
Numerical Simulations ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Larmor Radius ◽  
Collision Term ◽  
Magnetic Topology ◽  
Finite Larmor Radius ◽  
Confinement Mode

A model to describe an unmagnetised plasma in three-dimensional magnetic topology is presented. Ion trajectories are integrated numerically and all finite-Larmor radius effects are retained exactly. A velocity-dependent collision term is included in the equations of motion. Numerical simulations relevant to the low-confinement mode of H1-NF are presented and discussed.

Resistive instability in a uniformly rotating magnetoplasma

1971 ◽  
Vol 6 (1) ◽  
pp. 73-85
Author(s):  
A. D. Lunn
Keyword(s):  
Magnetic Field ◽  
Growth Rates ◽  
Larmor Radius ◽  
Closed Set ◽  
Finite Larmor Radius ◽  
Integral Methods ◽  
Stabilizing Effect ◽  
Instability Growth ◽  
Linear Differential ◽  
The Stability

A closed set of guiding centre equations, derived for a rotating plasma in a static magnetic field, is applied to the problem of the stability of a plasma in a sheared field. The rotation is found to have a stabilizing effect in the absence of resistivity.A pair of coupled, linear differential equations is derived for the rotating plasma in a weakly sheared field. Dispersion relations are obtained by phase integral methods and, in the absence of finite Larmor radius effects and rotation, instability growth rates proportional to η½13 are found which become proportional to when either is included. The inclusion of both finite Larmor radius and rotation gives growing instabilities proportional to η which are stabilized by the rotation when the finite Larmor radius terms predominate.

Effects of collisions and gyroviscosity on gravitational instability in a two-component plasma

1972 ◽  
Vol 8 (3) ◽  
pp. 393-400 ◽  
Author(s):  
F. Herrnegger
Keyword(s):  
Gravitational Instability ◽  
Larmor Radius ◽  
Finite Larmor Radius ◽  
Two Component ◽  
Component Plasma ◽  
Jeans Criterion ◽  
Fluid Theory ◽  
The Magnetic Field ◽  
Two Fluid ◽  
Critical Wavenumber

The dispersion relation for gravitational instability has been given within the framework of a two-fluid theory. It has been shown that the Jeans criterion is changed by finite Larmor radius and by collisions for waves propagating perpendicular to the magnetic field. The critical wavenumber for instability decreases with increasing Alfvén velocity and with increasing gyroviscosity. Instability does not set in with overstabiity.

Sign in / Sign up

Export Citation Format

Share Document