Two-fluid simulations of Rayleigh-Taylor instability in a magnetized solar prominence thread

Braileanu, B. Popescu; Lukin, V. S.; Khomenko, E.; Vicente, Á. de

doi:10.1051/0004-6361/202039053

Cited by 23 publications

(44 citation statements)

References 41 publications

(37 reference statements)

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“…They consist of partially ionized plasma with chromospheric-like properties. The density of this plasma is not high enough to fully couple the ionized and neutral species by collisions, and there exists a theoretical possibility that the dynamics of these components is not the same (Popescu Braileanu et al 2021a, 2021b. In most prominence studies, however, a single-fluid approach is used (see, e.g., Hillier 2018 for a review).…”

Section: Introductionmentioning

confidence: 99%

Doppler-velocity Drifts Detected in a Solar Prominence

Zapiór

Heinzel

Khomenko

2022

ApJ

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We analyzed multiline observations of a quiescent prominence from the slit spectrograph located at the Ondřejov Observatory. Dopplergrams and integrated intensity maps of the whole prominence were obtained from observations in six spectral lines: Ca ii H, Hϵ, Hβ, He i D3, Hα, and Ca ii IR. By combining integrated intensity maps with non-LTE radiative-transfer modeling, we carefully identified areas in an optically thin regime. The comparison of the Doppler-velocity maps and scatterplots from different lines shows the existence of differences in the velocity of ions and neutrals called velocity drift. The drift is of a local nature, present mostly at prominence edges in the area with a large velocity gradient, as can be tentatively expected based on multifluid MHD models. We could not explore the time evolution of the drift, since our data set consists of a single scan only. Our paper brings another contribution to a rather controversial problem of the detection of multifluid effects in solar prominences.

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Section: Introductionmentioning

confidence: 99%

Doppler-velocity Drifts Detected in a Solar Prominence

Zapiór

Heinzel

Khomenko

2022

ApJ

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“…The collisions can damp waves, similarly to the conclusion of Díaz et al (2012);Popescu Braileanu et al (2019b) and decrease the growth of the instabilities (Popescu Braileanu et al 2021a). We observed damping of waves and decoupling in velocity in 1D (Figure 3) and 2D (Figure 4) setups.…”

Section: Discussionmentioning

confidence: 69%

Two-fluid implementation in MPI-AMRVAC with applications to the solar chromosphere

Braileanu

Keppens

2022

A&A

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Context. The chromosphere is a partially ionized layer of the solar atmosphere, the transition between the photosphere where the gas is almost neutral and the fully ionized corona. As the collisional coupling between neutral and charged particles decreases in the upper part of the chromosphere, the hydrodynamical timescales may become comparable to the collisional timescale, and a two-fluid model is needed. Aims. In this paper we describe the implementation and validation of a two-fluid model which simultaneously evolves charges and neutrals, coupled by collisions. Methods. The two-fluid equations are implemented in the fully open-source MPI-AMRVAC code. In the photosphere and the lower part of the solar atmosphere, where collisions between charged and neutral particles are very frequent, an explicit time-marching would be too restrictive, since for stability the timestep needs to be proportional to the inverse of the collision frequency. This is overcome by evaluating the collisional terms implicitly using an explicit-implicit (IMEX) scheme. Out of the various IMEX variants implemented, we focus here on the IMEX-ARS3 scheme, used for all simulations presented in this paper. The modular structure of the code allows to directly apply all other code functionality -in particular its automated grid adaptivityto the two-fluid model. Results. Our implementation recovers and significantly extends available (analytic or numerical) test results for two-fluid charge-neutral evolutions. We demonstrate wave damping, propagation and interactions in stratified settings, Riemann problems for coupled plasma-neutral mixtures, generalize a shock-dominated evolution from single to two-fluid regimes, and make contact with recent findings on typical plasma-neutral instabilities. Conclusions. The cases presented cover very different collisional regimes and our results are fully consistent with related literature findings. If collisional time and length scales are smaller than the hydrodynamical scales usually considered in the solar chromosphere, density structures seen in the neutral and charged fluids are similar, with the effect of elastic collisions between charges and neutrals being similar to diffusivity. Otherwise, density structures are different and the decoupling in velocity between the two species increases, and neutrals may e.g. show Kelvin-Helmholtz roll-up while charges do not. The use of IMEX schemes efficiently avoids the small timestep constraints of fully explicit implementations in strongly collisional regimes. Adaptive Mesh Refinement (AMR) greatly decreases the computational cost, compared to uniform grid runs at the same effective resolution.

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“…In order to see how the energy transfers to smaller scales in the system, we compute the power spectrum of the velocity field by performing FFT of the v x component along the y direction (Popescu Braileanu et al, 2021). In particular, we consider the Fourier power at k y 2π/0.1 to track the wave's amplitude in the fundamental mode that was injected by the driver.…”

Section: Analysis and Resultsmentioning

confidence: 99%

Non-Linear Damping of Surface Alfvén Waves Due to Uniturbulence

Ismayilli

Doorsselaere

Goossens

et al. 2022

Front. Astron. Space Sci.

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This investigation is concerned with uniturbulence associated with surface Alfvén waves that exist in a Cartesian equilibrium model with a constant magnetic field and a piece-wise constant density. The surface where the equilibrium density changes in a discontinuous manner are the source of surface Alfvén waves. These surface Alfvén waves create uniturbulence because of the variation of the density across the background magnetic field. The damping of the surface Alfvén waves due to uniturbulence is determined using the Elsässer formulation. Analytical expressions for the wave energy density, the energy cascade, and the damping time are derived. The study of uniturbulence due to surface Alfvén waves is inspired by the observation that (the fundamental radial mode of) kink waves behave similarly to surface Alfvén waves. The results for this relatively simple case of surface Alfvén waves can help us understand the more complicated case of kink waves in cylinders. We perform a series of 3D ideal MHD simulations for a numerical demonstration of the non-linearly self-cascading model of unidirectional surface Alfvén waves using the code MPI-AMRVAC. We show that surface Alfvén waves damping time in the numerical simulations follows well our analytical prediction for that quantity. Analytical theory and the simulations show that the damping time is inversely proportional to the amplitude of the surface Alfvén waves and the density contrast. This unidirectional cascade may play a role in heating the coronal plasma.

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Two-fluid simulations of Rayleigh-Taylor instability in a magnetized solar prominence thread

Cited by 23 publications

References 41 publications

Doppler-velocity Drifts Detected in a Solar Prominence

Doppler-velocity Drifts Detected in a Solar Prominence

Two-fluid implementation in MPI-AMRVAC with applications to the solar chromosphere

Non-Linear Damping of Surface Alfvén Waves Due to Uniturbulence

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