Nonlinear studies of coronal heating by the resonant absorption of Alfvén waves

1994 ◽  
Vol 21 (20) ◽  
pp. 2259-2262 ◽  
Author(s):  
L. Ofman ◽  
J. M. Davila ◽  
R. S. Steinolfson
Keyword(s):  
Resonant Absorption ◽  
Alfven Waves ◽  
Coronal Heating ◽  
Alfvén Waves

Coronal heating by the resonant absorption of Alfven waves: Wavenumber scaling laws.

1995 ◽  
Vol 444 ◽  
pp. 471 ◽  
Author(s):  
L. Ofman ◽  
J. M. Davila ◽  
R. S. Steinolfson
Keyword(s):  
Scaling Laws ◽  
Resonant Absorption ◽  
Alfven Waves ◽  
Coronal Heating ◽  
Alfvén Waves

Solar coronal heating by Alfvén waves in bi-kappa distributed plasma

2019 ◽  
Vol 491 (2) ◽  
pp. 2403-2412 ◽  
Author(s):  
Imran A Khan ◽  
Z Iqbal ◽  
G Murtaza
Keyword(s):  
Distribution Function ◽  
Velocity Distribution ◽  
Particle Interaction ◽  
Velocity Distribution Function ◽  
Alfven Waves ◽  
Coronal Heating ◽  
Alfvén Waves ◽  
Heating Process ◽  
Thermal Features ◽  
Inertial Alfvén Waves

ABSTRACT In solar physics, there is a decades-old conundrum that is still unsolved. Why is the temperature of the corona so much larger than that of the surface of the Sun? To solve this, various approaches have been adopted so far, but they have certain limitations. In the present analysis, we invoke the standard Vlasov model and the steady-state Poynting theorem to unlock the mysterious coronal heating mechanism in terms of inertial and kinetic Alfvén waves whose electromagnetic energies turn into heat during wave–particle interaction. The coronal plasmas that support these waves are modelled by a non-thermal bi-kappa velocity distribution function. The non-thermal distribution function, which is assumed to pre-exist in the system, strongly influences the wave-heating process. Particularly, during heating by the waves in the inertial limit, the non-thermal features of the distribution function give rise to a unique competition (which is entirely absent in the usual Maxwellian plasmas) between waves of different perpendicular wavenumbers (kx). For small kx, when either the non-thermal parameter κ or the electron parallel temperature T||e increases, the inertial Alfvén waves can efficiently heat the plasma in their immediate vicinity. However, for relatively large kx, an increase in either κ or T||e enables the inertial Alfvén waves to effectively heat the plasma in remote regions in the corona. Although such competition is not seen in the kinetic limit, the non-thermal features still seem to control the heating process. The possible explanations behind the above-mentioned cases are provided by the bi-kappa velocity distribution function, which holds vital clues as to how the non-thermal features, together with kx, dictate the resonance conditions that play a crucial role in the heating process.

Unified theory of damping of linear surface Alfvén waves in inhomogeneous incompressible plasmas

1996 ◽  
Vol 56 (1) ◽  
pp. 107-125 ◽  
Author(s):  
M. S. Ruderman ◽  
M. Goossens
Keyword(s):  
Dispersion Relation ◽  
Resonant Absorption ◽  
Alfven Waves ◽  
Alfvén Waves ◽  
Dimensionless Number ◽  
Inhomogeneous Layer ◽  
Wide Range ◽  
Damping Rate ◽  
Nonmonotonic Variation ◽  
Incompressible Mhd

The viscous damping of surface Alfvén waves in a non-uniform plasma is studied in the context of linear and incompressible MHD. It is shown that damping due to resonant absorption and damping on a true discontinuity are two limiting cases of the continuous variation of the damping rate with respect to the dimensionless number Rg = Δλ2Re, where Δ is the relative variation of the local Alfvén velocity, λ is the ratio of the thickness of the inhomogeneous layer to the wavelength, and Re is the viscous Reynolds number. The analysis is restricted to waves with wavelengths that are long in comparison with the extent of the non-uniform layer (λ ≪ 1), and to Reynolds numbers that are sufficiently large that the waves are only slightly damped during one wave period. The dispersion relation is obtained and first investigated analytically for the limiting cases of very small (Rg ≪ 1) and very large (Rg ≫ 1) values of Rg, For very small values of Rg, the damping rate agrees with that found for a true discontinuity, while for very large values of Rg, it agrees with the damping rate due to resonant absorption. The dispersion relation is subsequently studied numerically over a wide range of values of Rg, revealing a continuous but nonmonotonic variation of the damping rate with respect to Rg.

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