scholarly journals MHD waves generated by high-frequency photospheric vortex motions

2011 ◽  
Vol 29 (6) ◽  
pp. 1029-1035 ◽  
Author(s):  
V. Fedun ◽  
S. Shelyag ◽  
G. Verth ◽  
M. Mathioudakis ◽  
R. Erdélyi
Keyword(s):  
Magnetic Flux ◽  
Solar Atmosphere ◽  
Flux Tube ◽  
High Frequency ◽  
Three Dimensional ◽  
Mhd Waves ◽  
Magnetic Flux Tube ◽  
Open Magnetic Flux ◽  
Cartesian Coordinate ◽  
Lower Solar Atmosphere

Abstract. In this paper, we discuss simulations of MHD wave generation and propagation through a three-dimensional 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 high-frequency 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.

scholarly journals Numerical simulations of the lower solar atmosphere heating by two-fluid nonlinear Alfvén waves

2020 ◽  
Vol 639 ◽  
pp. A45
Author(s):  
B. Kuźma ◽  
D. Wójcik ◽  
K. Murawski ◽  
D. Yuan ◽  
S. Poedts
Keyword(s):  
Magnetic Flux ◽  
Numerical Simulations ◽  
Solar Atmosphere ◽  
Flux Tube ◽  
Alfven Waves ◽  
Alfven Wave ◽  
Magnetic Flux Tube ◽  
Alfvén Waves ◽  
Two Fluid ◽  
Lower Solar Atmosphere

Context. We present new insight into the long-standing problem of plasma heating in the lower solar atmosphere in terms of collisional dissipation caused by two-fluid Alfvén waves. Aims. Using numerical simulations, we study Alfvén wave propagation and dissipation in a magnetic flux tube and their heating effect. Methods. We set up 2.5-dimensional numerical simulations with a semi-empirical model of a stratified solar atmosphere and a force-free magnetic field mimicking a magnetic flux tube. We consider a partially ionized plasma consisting of ion + electron and neutral fluids, which are coupled by ion-neutral collisions. Results. We find that Alfvén waves, which are directly generated by a monochromatic driver at the bottom of the photosphere, experience strong damping. Low-amplitude waves do not thermalize sufficient wave energy to heat the solar atmospheric plasma. However, Alfvén waves with amplitudes greater than 0.1 km s−1 drive through ponderomotive force magneto-acoustic waves in higher atmospheric layers. These waves are damped by ion-neutral collisions, and the thermal energy released in this process leads to heating of the upper photosphere and the chromosphere. Conclusions. We infer that, as a result of ion-neutral collisions, the energy carried initially by Alfvén waves is thermalized in the upper photosphere and the chromosphere, and the corresponding heating rate is large enough to compensate radiative and thermal-conduction energy losses therein.

Very Fast Opening of a Three-dimensional Twisted Magnetic Flux Tube

1996 ◽  
Vol 466 (1) ◽  
pp. L39-L42 ◽  
Author(s):  
T. Amari ◽  
J. F. Luciani ◽  
J. J. Aly ◽  
M. Tagger
Keyword(s):  
Magnetic Flux ◽  
Flux Tube ◽  
Three Dimensional ◽  
Magnetic Flux Tube ◽  
Twisted Magnetic Flux Tube

scholarly journals Effects of MHD slow shocks propagating along magnetic flux tubes in a dipole magnetic field

2002 ◽  
Vol 9 (2) ◽  
pp. 163-172 ◽  
Author(s):  
N. V. Erkaev ◽  
V. A. Shaidurov ◽  
V. S. Semenov ◽  
H. K. Biernat
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Flux Tube ◽  
Plasma Pressure ◽  
Mhd Waves ◽  
Magnetic Flux Tube ◽  
Flux Tubes ◽  
Dipole Magnetic Field ◽  
Pressure Pulses ◽  
Magnetic Flux Tubes

Abstract. Variations of the plasma pressure in a magnetic flux tube can produce MHD waves evolving into shocks. In the case of a low plasma beta, plasma pressure pulses in the magnetic flux tube generate MHD slow shocks propagating along the tube. For converging magnetic field lines, such as in a dipole magnetic field, the cross section of the magnetic flux tube decreases enormously with increasing magnetic field strength. In such a case, the propagation of MHD waves along magnetic flux tubes is rather different from that in the case of uniform magnetic fields. In this paper, the propagation of MHD slow shocks is studied numerically using the ideal MHD equations in an approximation suitable for a thin magnetic flux tube with a low plasma beta. The results obtained in the numerical study show that the jumps in the plasma parameters at the MHD slow shock increase greatly while the shock is propagating in the narrowing magnetic flux tube. The results are applied to the case of the interaction between Jupiter and its satellite Io, the latter being considered as a source of plasma pressure pulses.

scholarly journals Waves in Magnetic Flux Tubes

1990 ◽  
Vol 142 ◽  
pp. 159-174
Author(s):  
B Roberts
Keyword(s):  
Wave Propagation ◽  
Magnetic Flux ◽  
Solar Atmosphere ◽  
Flux Tube ◽  
Seismic Waves ◽  
Wave Guide ◽  
Magnetic Flux Tube ◽  
Flux Tubes ◽  
Ocean Layer ◽  
Magnetic Flux Tubes

The basic aspects of wave propagation in a magnetic flux tube are reviewed, with particular emphasis on the types of flux tube that occur in the solar atmosphere. Two fundamental speeds arise naturally in a description of wave propagation in a flux tube: the slow magnetoacoustic (cusp) speed cT, which is both subsonic and sub-Alfvénic, and a mean Alfvén speed ck. Both surface and body modes are supported by a tube. It is stressed that a flux tube may act as a wave guide, similar to the guidance of light by a fibre optic, or sound in an ocean layer, or seismic waves in the Earth's crust.

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