Time damping of linear non-adiabatic magnetohydrodynamic waves in an unbounded 
plasma with solar coronal properties

Carbonell, M.; Oliver, R.; Ballester, J. L.

doi:10.1051/0004-6361:20034630

Cited by 66 publications

(81 citation statements)

References 27 publications

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“…Turning our attention to the slow wave (Fig. 2c), we see that the maximum and the right hand side minimum of τ D /P are also slightly shifted toward lower values of k. Results from Carbonell et al (2004) and Forteza et al (2008) indicate that thermal conduction is responsible for the maximum and minimum of τ D /P. Thus, the additional contribution of neutral helium atoms to thermal conduction (Eq.…”

Section: Free Propagation In An Unbounded Mediummentioning

confidence: 85%

“…In a subsequent work (Forteza et al 2008), they extended their previous analysis by considering radiative losses and thermal conduction by electrons and neutrals. Their main results with respect to the fully ionized case (Carbonell et al 2004) were, first of all, that ion-neutral collisions (by means of the so-called Cowling's diffusion) can damp both Alfvén and fast waves but non-adiabatic effects remain only important for the damping of slow and thermal waves, and second, that critical values of the wavenumber exist in which the real part of the frequency vanishes, so wave propagation is impossible for larger wavenumbers. Again, applications to a more complex cylindrical geometry have also been performed (Soler et al 2009b,c).…”

Section: Introductionmentioning

confidence: 99%

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Time damping of non-adiabatic magnetohydrodynamic waves in a partially ionized prominence plasma: effect of helium

Soler

Oliver

Ballester

2010

A&A

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Context. Prominences are partially ionized, magnetized plasmas embedded in the solar corona. Damped oscillations and propagating waves are commonly observed. These oscillations have been interpreted in terms of magnetohydrodynamic (MHD) waves. Ion-neutral collisions and non-adiabatic effects (radiation losses and thermal conduction) have been proposed as damping mechanisms. Aims. We study the effect of the presence of helium on the time damping of non-adiabatic MHD waves in a plasma composed by electrons, protons, neutral hydrogen, neutral helium (He i), and singly ionized helium (He ii) in the single-fluid approximation.Methods. The dispersion relation of linear non-adiabatic MHD waves in a homogeneous, unbounded, and partially ionized prominence medium is derived. We compute the period and the damping time of Alfvén, slow, fast, and thermal waves. A parametric study of the ratio of the damping time to the period with respect to the helium abundance is performed.Results. The efficiency of ion-neutral collisions, as well as thermal conduction, is increased by the presence of helium. However, if realistic abundances of helium in prominences (∼10%) are considered, this has a minor influence on the wave damping. Conclusions. The presence of helium can be safely neglected in studies of MHD waves in partially ionized prominence plasmas.

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Section: Free Propagation In An Unbounded Mediummentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Time damping of non-adiabatic magnetohydrodynamic waves in a partially ionized prominence plasma: effect of helium

Soler

Oliver

Ballester

2010

A&A

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“…For instance, for fully ionised plasmas, the time damping of prominence oscillations has been studied by considering non-adiabatic MHD waves, including the effects of optically thin radiation, thermal conduction, and heating, in unbounded and bounded prominence slabs (Carbonell et al 2004;Terradas et al 2005), prominence slabs surrounded by an infinite solar corona (Soler et al 2007) and bounded prominence-corona slabs (Soler et al 2009c). On the other hand, taking into account the fine prominence structure, and assuming that the threads forming solar filaments can be modeled as cylindrical flux tubes filled with fully ionised prominence plasma surrounded by the solar corona, the time damping of inhomogeneous cylindrical flux tubes due to resonant absorption has been studied by Arregui et al (2008).…”

Section: Introductionmentioning

confidence: 99%

Time damping of non-adiabatic magnetohydrodynamic waves in a partially ionised prominence medium: Effect of a background flow

Barceló

Carbonell

Ballester

2010

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Context. The simultaneous occurrence of flows and time damped small-amplitude oscillations in solar prominences is a common phenomenon. These oscillations are mostly interpreted in terms of magnetohydrodynamic (MHD) waves. Aims. We study the time damping of linear non-adiabatic MHD waves in a flowing partially ionised plasma with prominence-like physical conditions. Methods. Considering non-adiabatic single fluid equations for a partially ionised hydrogen plasma, we have solved our dispersion relations for the complex frequency, ω, and we have analysed the behavior of the period, damping time and the ratio of the damping time to the period, versus the real wavenumber k, for Alfvén, fast, slow, and thermal waves. Results. While in the case without flow there is a critical wavenumber at which the period of Alfvén and fast waves goes to infinite, when a flow is present two different critical wavenumbers appear. The smaller wavenumber depends on the flow speed and causes the period of the high-period branch to go to infinite. When the second critical wavenumber is attained the period of both branches become equal. In general, the time damping of Alfvén and fast waves is dominated by resistive effects, and its damping ratio is very inefficient when compared to observations. The damping of slow and thermal waves is basically dominated by non-adiabatic effects, and for slow waves it is possible to obtain a damping ratio close to observations, although it would correspond to long period oscillations with large damping times not often observed. The consideration of a structured medium produces new features such as the apparition of four critical wavenumbers for Alfvén waves, and one critical wavenumber for slow waves. For fast waves, constrained propagation substantially improves, within the range of observed wavelengths, the ratio of the damping time to period. Conclusions. The presence of a background flow in a partially ionised plasma gives place to new interesting features when the time damping of MHD waves is studied. In general, the results point out that ion-neutral collisions are an inefficient mechanism to explain the observed time damping of prominence oscillations if they are produced by Alfvén and fast waves. If the oscillations are produced by slow waves, only long period oscillations with large damping times produce damping ratios in agreement with observations.

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“…This means that for a typical period of 10 3 s, the damping length would be between 10 2 and 10 3 km, the wavelength around 10 3 km and, as a consequence, in a distance smaller than a wavelength the slow wave would be strongly attenuated. On the other hand, during our calculations, we have found that the different heating mechanisms usually considered (Carbonell et al 2004) do not affect the results.…”

Section: Discussionmentioning

confidence: 53%

“…These small-amplitude oscillations have been commonly interpreted in terms of linear magnetohydrodynamic (MHD) waves and the damping of oscillations has been studied by considering different dissipative mechanisms. For instance, in the case of fully ionised plasmas, the time damping of prominence oscillations has been studied by considering non-adiabatic MHD waves, including the effects of optically thin radiation, thermal conduction, and heating, in unbounded and bounded prominence plasmas (Carbonell et al 2004;Terradas et al 2005). By assuming that the threads of which the solar filaments consist can be modeled as cylindrical flux tubes, the time damping of homogeneous and inhomogeneous cylindrical flux tubes, with prominence physical conditions, has been modeled using thermal mechanisms and resonant absorption, respectively (Soler et al 2008;Arregui et al 2008;Soler et al 2009b).…”

Section: Introductionmentioning

confidence: 99%

The spatial damping of magnetohydrodynamic waves in a flowing partially ionised prominence plasma

Carbonell¹,

Forteza²,

Oliver³

et al. 2010

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Context. Solar prominences are partially ionised plasmas displaying flows and oscillations. These oscillations exhibit time and spatial damping and have commonly been explained in terms of magnetohydrodynamic (MHD) waves. Aims. We study the spatial damping of linear non-adiabatic MHD waves in a flowing partially ionised plasma with prominence-like physical properties. Methods. We consider single fluid equations for a partially ionised hydrogen plasma by including in the energy equation optically thin radiation, thermal conduction by electrons and neutrals, and heating. By keeping ω real and fixed, we solved the dispersion relations obtained for the complex wavenumber, k, and analysed the behaviour of the damping length, wavelength and the ratio of the damping length to the wavelength, versus period, for Alfvén, fast, slow, and thermal waves. Results. In the presence of a background flow, the results indicate that new strongly damped fast and Alfvén waves appear that depend on the joint action of flow and resistivity. The damping lengths of adiabatic fast and slow waves are strongly affected by partial ionisation, which also modifies the ratio between damping lengths and wavelengths. The behaviour of adiabatic fast waves also resembles that of Alfvén waves. For non-adiabatic slow waves, the unfolding in both wavelength and damping length induced by the flow allows efficient damping to be found for periods compatible with those observed in prominence oscillations. This effect is enhanced when low ionised plasmas are considered. Conclusions. Since flows are ubiquitous in prominences, in the case of non-adiabatic slow waves and within the range of periods of interest for prominence oscillations, the joint effect of both flow and partial ionisation leads to a ratio of damping length to wavelength denoting a very efficient spatial damping. For fast and Alfvén waves, the most efficient damping occurs at very short periods not compatible with those observed in prominence oscillations.

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Time damping of linear non-adiabatic magnetohydrodynamic waves in an unbounded plasma with solar coronal properties

Cited by 66 publications

References 27 publications

Time damping of non-adiabatic magnetohydrodynamic waves in a partially ionized prominence plasma: effect of helium

Time damping of non-adiabatic magnetohydrodynamic waves in a partially ionized prominence plasma: effect of helium

Time damping of non-adiabatic magnetohydrodynamic waves in a partially ionised prominence medium: Effect of a background flow

The spatial damping of magnetohydrodynamic waves in a flowing partially ionised prominence plasma

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