Multicomponent theory of buoyancy instabilities in magnetized plasmas: The case of magnetic field parallel to gravity

Abstract

We investigate electromagnetic buoyancy instabilities of the electron-ion plasma with the heat flux based on not the magnetohydrodynamic (MHD) equations, but using the multicomponent plasma approach when the momentum equations are solved for each species. We consider a geometry in which the background magnetic field, gravity, and stratification are directed along one axis. The nonzero background electron thermal flux is taken into account. Collisions between electrons and ions are included in the momentum equations. No simplifications usual for the one-fluid MHD-approach in studying these instabilities are used. We derive a simple dispersion relation, which shows that the thermal flux perturbation generally stabilizes an instability for the geometry under consideration. This result contradicts to conclusion obtained in the MHD-approach. We show that the reason of this contradiction is the simplified assumptions used in the MHD analysis of buoyancy instabilities and the role of the longitudinal electric field perturbation which is not captured by the ideal MHD equations. Our dispersion relation also shows that the medium with the electron thermal flux can be unstable, if the temperature gradients of ions and electrons have the opposite signs. The results obtained can be applied to the weakly collisional magnetized plasma objects in laboratory and astrophysics.

Accepted for publication in Astrophysics & Space Science

References in corpus (4)

• Buoyancy Instabilities in Weakly Magnetized Low Collisionality Plasmas
• Anisotropic Thermal Conduction and the Cooling Flow Problem in Galaxy Clusters
• Electromagnetic streaming instabilities of magnetized accretion disks with strong collisional coupling of species
• Multicomponent theory of buoyancy instabilities in astrophysical plasma objects: The case of magnetic field perpendicular to gravity

Cited by in corpus (3)

• Electromagnetic thermal instability with momentum and energy exchange between electrons and ions in galaxy clusters
• Streaming cold cosmic ray back-reaction and thermal instabilities across the background magnetic field
• Influence of energy exchange of electrons and ions on the long-wavelength thermal instability in magnetized astrophysical objects