Magnetic Transport on the Solar Atmosphere by Laminar and Turbulent Ambipolar Diffusion

Hiraki, Y.; Krishan, V.; Masuda, S.

doi:10.1088/0004-637x/720/2/1311

Cited by 4 publications

(2 citation statements)

References 12 publications

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“…Nevertheless, many other works in solar physics use the terminology introduced by Spitzer, i.e. "ambipolar diffusion", see (Chitre & Krishan, 2001;Soler et al, 2009Soler et al, , 2010Hiraki et al, 2010;Singh et al, 2011;Cheung & Cameron, 2012;Martínez-Sykora et al, 2012;Soler et al, 2012;Tsap et al, 2012;Díaz et al, 2012;.…”

Section: Appendix A: Notes On the Nomenclaturementioning

confidence: 99%

Rayleigh-Taylor instability in prominences from numerical simulations including partial ionization effects

Khomenko

Díaz

Vicente

et al. 2014

A&A

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We study the Rayleigh-Taylor instability (RTI) at a prominence-corona transition region in a non-linear regime. Our aim is to understand how the presence of neutral atoms in the prominence plasma influences the instability growth rate, as well as the evolution of velocity, magnetic field vector, and thermodynamic parameters of turbulent drops. We perform 2.5D numerical simulations of the instability initiated by a multi-mode perturbation at the corona-prominence interface using a single-fluid magnetohydrodynamic (MHD) approach including a generalized Ohm's law. The initial equilibrium configuration is purely hydrostatic and contains a homogeneous horizontal magnetic field forming an angle with the direction in which the plasma is perturbed. We analyze simulations with two different orientations of the magnetic field. For each field orientation we compare two simulations, one for the pure MHD case, and one including the ambipolar diffusion in Ohm's law (AD case). Other than that, both simulations for each field orientation are identical. The numerical results in the initial stage of the instability are compared with the analytical linear calculations. We find that the configuration is always unstable in the AD case. The growth rate of the small-scale modes in the non-linear regime is up to 50% larger in the AD case than in the purely MHD case and the average velocities of flows are a few percentage points higher. Significant drift momenta are found at the interface between the coronal and the prominence material at all stages of the instability, produced by the faster downward motion of the neutral component with respect to the ionized component. The differences in temperature of the bubbles between the ideal and non-ideal case are also significant, reaching 30%. There is an asymmetry between large rising bubbles and small-scale down flowing fingers, favoring the detection of upward velocities in observations.

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Section: Appendix A: Notes On the Nomenclaturementioning

confidence: 99%

Rayleigh-Taylor instability in prominences from numerical simulations including partial ionization effects

Khomenko

Díaz

Vicente

et al. 2014

A&A

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“…The present estimates of Hm and Am are broadly in agreement with those of Khomenko & Collados () and Sykora, De Pontieu & Hansteen (). For sub‐Alfvénic motion (Hiraki, Krishan & Masuda ), both Hm and Am can become of the order of unity or less. For a 0.1‐kG field (Fig.…”

Section: Basic Modelmentioning

confidence: 99%

Hall instability of solar flux tubes in the presence of shear flows

Pandey

Wardle

2012

Monthly Notices of the Royal Astronomical Society

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The magnetic network, which consists of vertical flux tubes located in intergranular lanes, is dominated by Hall drift in the photosphere-lower chromosphere region ( 1 Mm). In the internetwork regions with weak magnetic field, Hall drift dominates above 0.25 Mm in the photosphere and below 2.5 Mm in the chromosphere. Although Hall drift does not cause any dissipation in the ambient plasma, it can destabilize the flux tubes and magnetic elements in the presence of azimuthal shear flow. The physical mechanism of this instability is quite simple. The shear flow twists the radial magnetic field and generates an azimuthal field. Then, torsional oscillations of the azimuthal field, in turn, generate the radial field, completing feedback loop. The maximum growth rate of Hall instability is proportional to the absolute value of the shear gradient, and it is dependent on the ambient diffusivity. The diffusivity also determines the most unstable wavelength, which is smaller for weaker fields.We apply the results of a local stability analysis to the network and internetwork magnetic elements and show that the maximum growth rate for a kiloGauss field occurs around 0.5 Mm and decreases with increasing altitude. However, for a 120-G field, the maximum growth rate remains almost constant in the entire photosphere-lower chromosphere, except in a small region closer to the surface. For a shear flow gradient ∼0.1 s −1 , the Hall growth time is about 1 min near the photospheric footpoint. Therefore, network and internetwork regions with an intense field in the presence of shear flow are likely to be unstable in the photosphere. The weak field internetwork regions could be unstable in the entire photosphere-chromosphere. Thus, Hall instability can play an important role in generating low-frequency turbulence, which can heat the chromosphere.

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Different representations of a partially ionized plasma

Krishan

2022

J Astrophys Astron

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Magnetic Transport on the Solar Atmosphere by Laminar and Turbulent Ambipolar Diffusion

Cited by 4 publications

References 12 publications

Rayleigh-Taylor instability in prominences from numerical simulations including partial ionization effects

Rayleigh-Taylor instability in prominences from numerical simulations including partial ionization effects

Hall instability of solar flux tubes in the presence of shear flows

Different representations of a partially ionized plasma

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