Dissipative instability in partially ionised prominence plasmas

Abstract

We investigate the nature of dissipative instability at the boundary (seen here as tangential discontinuity) between the viscous corona and the partially ionised prominence plasma in the incompressible limit. The importance of the partial ionisation is investigated in terms of the ionisation fraction. Matching the solutions for the transversal component of the velocity and total pressure at the interface between the prominence and coronal plasmas, we derive a dispersion relation whose imaginary part describes the evolution of the instability. Results are obtained in the limit of weak dissipation. Using simple analytical methods, we show that dissipative instabilities appear for flow speeds that are lower than the Kelvin-Helmholtz instability threshold. While viscosity tends to destabilise the plasma, the effect of partial ionisation (through the Cowling resistivity) will act towards stabilising the interface. For ionisation degrees closer to a neutral gas the interface will be unstable for larger values of equilibrium flow. The same principle is assumed when studying the appearance of instability at the interface between prominences and dark plumes. The unstable mode appearing in this case has a very small growth rate and dissipative instability cannot explain the appearance of flows in plumes. The present study improves our understanding of the complexity of dynamical processes at the interface of solar prominences and solar corona, and the role partial ionisation can have on the stability of the plasma. Our results clearly show that the problem of partial ionisation introduces new aspects of plasma stability with consequences on the evolution of solar prominences.

arXiv comment8 pages, 2 figures

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Cited by in corpus (10)

• Partially Ionized Plasmas in Astrophysics
• On the effects of ion-neutral interactions in solar plasmas
• Viscous effects on the Rayleigh-Taylor instability with background temperature gradient
• Small-scale solar jet formation and their associated waves and instabilities
• Excitation of negative energy surface magnetohydrodynamic waves in an incompressible cylindrical plasma
• Dispersive shock waves in partially ionised plasmas
• Dissipative instability in a partially ionised prominence slab
• Dissipative instabilities in a partially ionised prominence plasma slab: II. The effect of compressibility
• Dissipative Instability of Magnetohydrodynamic Sausage Waves in a Compressional Cylindrical Plasma: Effect of Flow Shear and Viscosity Shear
• Alfven Waves in Partially Ionised Solar Steady-State Plasmas