The transformation of MHD Alfvén waves in space plasma

Fedun, V.N.; Yukhimuk, A. K.; Voitsekhovskaya, A. D.

doi:10.1017/s0022377804002909

Cited by 11 publications

(10 citation statements)

References 14 publications

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“…This requires much more detailed numerical and analytical analysis. For more efficient heating due to MHD waves, these waves must transfer their energy to smaller length scales due to various types of instability and dissipation mechanisms (see Fedun et al, 2004;Copil et al, 2010). In order to resolve the dissipation numerically very powerful high performance computational equipment is needed and we hope to make the first steps in this direction in the near future.…”

Section: Discussionmentioning

confidence: 99%

MHD waves generated by high-frequency photospheric vortex motions

et al. 2011

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Abstract.In this paper, we discuss simulations of MHD wave generation and propagation through a threedimensional open magnetic flux tube in the lower solar atmosphere. By using self-similar analytical solutions for modelling the magnetic field in Cartesian coordinate system, we have constructed a 3-D magnetohydrostatic configuration which is used as the initial condition for non-linear MHD wave simulations. For a driver we have implemented a highfrequency vortex-type motion at the footpoint region of the open magnetic flux tube. It is found that the implemented swirly source is able to excite different types of wave modes, i.e. sausage, kink and torsional Alfvén modes. Analysing these waves by magneto-seismology tools could provide insight into the magnetic structure of the lower solar atmosphere.

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Section: Discussionmentioning

confidence: 99%

MHD waves generated by high-frequency photospheric vortex motions

et al. 2011

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“…There is evidence that the higher‐frequency waves are kinetic Alfvén waves, that they are damped when they are near or above the local ion gyrofrequency, and that they are also generated between Polar and FAST. This generation mechanism is open to speculation, but the energy to generate them may come from the lower‐frequency Alfvén waves [ Chaston et al , 2003b; Wu , 2003; Fedun et al , 2004; Watt et al , 2004; Voitenko and Goossens , 2005]. Since kinetic Alfvén waves contain a parallel electric field which can accelerate electrons [ Hasegawa , 1976; Goertz and Boswell , 1979] conversion of the lower‐frequency Alfvén waves into kinetic Alfvén waves provides a possible mechanism for the lower‐frequency Alfvén wave Poynting flux at Polar to power the auroral acceleration process.…”

Section: Observations and Discussionmentioning

confidence: 99%

Alfvén waves and Poynting flux observed simultaneously by Polar and FAST in the plasma sheet boundary layer

et al. 2005

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[1] We present the first simultaneous observations of Alfvén waves at Polar and FAST altitudes, $7 R E geocentric and $3500 km, respectively, at $23 MLT in the main phase of a major geomagnetic storm on 22 October 1999. We compare the Poynting flux for these waves and the electron energy flux at the two spacecraft. We also present a new method of Alfvén wave analysis, examining Poynting flux magnitude and directionality along with the perturbation electric to magnetic field ratio of these waves as a function of wave temporal scale (frequency). The results of this analysis are compared with those expected from kinetic Alfvén wave models. There is a mean net loss of $2.1 ergs cm

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“…These motions are found at photospheric bright points, thus suggesting the magnetic nature of the photospheric vortices. On the other hand, as it has recently been demonstrated by forward modelling (Shelyag et al, 2008;Fedun et al, 2009Fedun et al, , 2011, the motions, which occur at the footpoints of photospheric magnetic flux tubes, effectively leak into the higher layers of the solar atmosphere thus eventually reaching the corona and transporting energy into it (Fedun et al, 2004;Erdélyi and Fedun, 2007;Taroyan, 2008; Correspondence to: S. Shelyag (s.shelyag@qub.ac.uk) Taroyan and Erdélyi, 2009;Antolin and Shibata, 2010). Thus, it is suggested that vortex motions in the photosphere may act as one of the potential mechanisms of energy supply to the upper solar atmosphere.…”

Section: Introductionmentioning

confidence: 99%

Photospheric magnetic vortex structures

et al. 2011

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Abstract. Using direct numerical magneto-hydrodynamic (MHD) simulations, we demonstrate the evidence of two physically different types of vortex motions in the solar photosphere. Baroclinic motions of plasma in non-magnetic granules are the primary source of vorticity in granular regions of the solar photosphere, however, there is a significantly more efficient mechanism of vorticity production in strongly magnetised intergranular lanes. These swirly motions of plasma in intergranular magnetic field concentrations could be responsible for the generation of different types of MHD wave modes, for example, kink, sausage and torsional Alfvén waves. These waves could transport a relevant amount of energy from the lower solar atmosphere and contribute to coronal plasma heating.

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The transformation of MHD Alfvén waves in space plasma

Cited by 11 publications

References 14 publications

MHD waves generated by high-frequency photospheric vortex motions

MHD waves generated by high-frequency photospheric vortex motions

Alfvén waves and Poynting flux observed simultaneously by Polar and FAST in the plasma sheet boundary layer

Photospheric magnetic vortex structures

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