On the nature of kink MHD waves in magnetic flux tubes

Goossens, Marcel; Terradas, J.; Andries, Jesse; Arregui, I.; Ballester, J. L.

doi:10.1051/0004-6361/200912399

Cited by 204 publications

(240 citation statements)

References 36 publications

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“…Kink waves are transverse waves with mixed fast MHD and Alfvénic properties (see, e.g., Edwin & Roberts 1983;Goossens et al 2009). In thin magnetic tubes kink waves are highly Alfvénic because their dominant restoring force is magnetic tension (Goossens et al 2009).…”

Section: Introductionmentioning

confidence: 99%

Resonant Alfvén waves in partially ionized plasmas of the solar atmosphere

Soler

Andries

Goossens

2012

A&A

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Context. Magnetohydrodynamic (MHD) waves are ubiquitous in the solar atmosphere. In magnetic waveguides resonant absorption due to plasma inhomogeneity naturally transfers wave energy from large-scale motions to small-scale motions. In the cooler parts of the solar atmosphere as, e.g., the chromosphere, effects due to partial ionization may be relevant for wave dynamics and heating. Aims. We study resonant Alfvén waves in partially ionized plasmas. Methods. We use the multifluid equations in the cold plasma approximation. We investigate propagating resonant MHD waves in partially ionized flux tubes. We use approximate analytical theory based on normal modes in the thin tube and thin boundary approximations along with numerical eigenvalue computations. Results. We find that the jumps of the wave perturbations across the resonant layer are the same as in fully ionized plasmas. The damping length due to resonant absorption is inversely proportional to the frequency, while that due to ion-neutral collisions is inversely proportional to the square of the frequency. For observed frequencies in the solar atmosphere, the amplitude of MHD kink waves is more efficiently damped by resonant absorption than by ion-neutral collisions. Conclusions. Most of the energy carried by chromospheric kink waves is converted into localized azimuthal Alfvén waves that can deposit energy in the coronal medium. The dissipation of wave energy in the chromosphere due to ion-neutral collisions is only effective for high-frequency waves. The chromosphere acts as a filter for kink waves with periods shorter than 10 s.

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Section: Introductionmentioning

confidence: 99%

Resonant Alfvén waves in partially ionized plasmas of the solar atmosphere

Soler

Andries

Goossens

2012

A&A

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“…Complex frequencies, to account for damping of these MHD waves, were considered by Wilson (1979) for a magnetic field-free environment, whilst Spruit (1982) and Cally (1986) made some of the first rigorous investigations into damping as a result of energy losses into the surrounding magnetic atmosphere. Later works have expanded upon the results found therein; perhaps the most relevant to this article were the efforts made of combining the damping through energy leakage and resonant absorption as investigated by Goossens and Hollweg (1993), Stenuit et al (1999), and Goossens et al (2009). For a review of the resonant absorption as discussed in these works, see e.g.…”

Section: Introductionmentioning

confidence: 92%

“…Equation (66) in Goossens et al (2009). By rewriting Equation (16) in terms of the density ratio, χ , it is possible to write…”

Section: Damping Coefficientmentioning

confidence: 99%

Linear MHD Wave Propagation in Time-Dependent Flux Tube

Williamson

Erdélyi

2015

Sol Phys

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In this article, we evaluate the time-dependent wave properties and the damping rate of propagating fast magneto-hydrodynamic (MHD) waves when energy leakage into a magnetised atmosphere is considered. By considering a cold plasma, initial investigations into the evolution of MHD wave damping through this energy leakage will take place. The time-dependent governing equations have been derived previously in Williamson and Erdé-lyi (2014a, Solar Phys. 289, 899 -909) and are now solved when the assumption of evanescent wave propagation in the outside of the waveguide is relaxed. The dispersion relation for leaky waves applicable to a straight magnetic field is determined in both an arbitrary tube and a thin-tube approximation. By analytically solving the dispersion relation in the thin-tube approximation, the explicit expressions for the temporal evolution of the dynamic frequency and wavenumber are determined. The damping rate is, then, obtained from the dispersion relation and is shown to decrease as the density ratio increases. By comparing the decrease in damping rate to the increase in damping for a stationary system, as shown, we aim to point out that energy leakage may not be as efficient a damping mechanism as previously thought.

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“…Hence, it is readily observed in over-dense solar structures with imagers of sufficient spatial and/or temporal resolution. The kink mode is highly Alfvénic, since its main restoring force is magnetic tension, thereby making it only weakly compressible [see, e.g., Goossens et al, 2009, for a detailed discussion]. Kink waves have been most extensively studied in the corona following the launch of the Transition Region and Coronal Explorer [TRACE; Handy et al, 1999] spacecraft in 1998.…”

Section: Kink Wavesmentioning

confidence: 99%