Two-fluid simulations of Rayleigh-Taylor instability in a magnetized solar prominence thread II. Effects of collisionality

TL;DR

This study uses two-fluid simulations to analyze how ion-neutral collisions influence the Rayleigh-Taylor instability in magnetized solar prominence threads, revealing their role in structure development and flow decoupling.

Contribution

It investigates the effects of collisionality on RTI in partially ionized plasmas, highlighting the importance of ion-neutral collision frequency and magnetic configuration in instability evolution.

Findings

Ionization/recombination reactions do not significantly affect primary RTI development.

Collisionality influences the formation of small-scale structures in RTI.

Flow decoupling between ions and neutrals depends on collisionality and magnetic field configuration.

Abstract

In this work, we explore the dynamical impacts and observable signatures of two-fluid effects in the parameter regimes when ion-neutral collisions do not fully couple the neutral and charged fluids. The purpose of this study is to deepen our understanding of the RTI and the effects of the partial ionization on the development of RTI using non-linear two-fluid numerical simulations. Our two-fluid model takes into account neutral viscosity, thermal conductivity, and collisional interaction between neutrals and charges: ionization/recombination, energy and momentum transfer, and frictional heating. In this paper II, the sensitivity of the RTI dynamics to collisional effects for different magnetic field configurations supporting the prominence thread is explored. This is done by artificially varying, or eliminating, effects of both elastic and inelastic collisions by modifying the model equations. We find that ionization and recombination reactions between ionized and neutral fluids, if in equilibrium prior to the onset of the instability, do not substantially impact the development of the primary RTI. However, such reactions can impact development of secondary structures during mixing of the cold prominence and hotter surrounding coronal material. We find that collisionality within and between ionized and neutral particle populations play an important role in both linear and non-linear development of RTI, with ion-neutral collision frequency as the primary determining factor in development or damping of small scale structures. We also observe that degree and signatures of flow decoupling between ion and neutral fluids can depend both on the inter-particle collisionality and the magnetic field configuration of the prominence thread.