scholarly journals On the MHD stability of the $\vec m$ = 1 kink mode in solar coronal loops

2001 ◽  
Vol 367 (1) ◽  
pp. 321-325 ◽  
Author(s):  
H. Baty
Keyword(s):  
Coronal Loops ◽  
Kink Mode ◽  
Mhd Stability ◽  
Solar Coronal

scholarly journals Dynamics of solar coronal loops

2003 ◽  
Vol 411 (3) ◽  
pp. 605-613 ◽  
Author(s):  
D. A. N. Müller ◽  
V. H. Hansteen ◽  
H. Peter
Keyword(s):  
Coronal Loops ◽  
Solar Coronal

MULTI-STRANDED AND MULTI-THERMAL SOLAR CORONAL LOOPS: EVIDENCE FROMHINODEX-RAY TELESCOPE AND EUV IMAGING SPECTROMETER DATA

2010 ◽  
Vol 723 (2) ◽  
pp. 1180-1187 ◽  
Author(s):  
J. T. Schmelz ◽  
S. H. Saar ◽  
K. Nasraoui ◽  
V. L. Kashyap ◽  
M. A. Weber ◽  
...  
Keyword(s):  
Coronal Loops ◽  
Imaging Spectrometer ◽  
Spectrometer Data ◽  
Euv Imaging ◽  
Solar Coronal

scholarly journals 3-D numerical simulations of coronal loops oscillations

2009 ◽  
Vol 27 (10) ◽  
pp. 3899-3908 ◽  
Author(s):  
M. Selwa ◽  
L. Ofman
Keyword(s):  
Active Regions ◽  
External Source ◽  
Coronal Loops ◽  
Velocity Perturbation ◽  
Impulsive Excitation ◽  
Kink Mode ◽  
Parametric Studies ◽  
Field Lines ◽  
Significant Distance

Abstract. We present numerical results of 3-D MHD model of a dipole active region field containing a loop with a higher density than its surroundings. We study different ways of excitation of vertical kink oscillations by velocity perturbation: as an initial condition, and as an impulsive excitation with a pulse of a given position, duration, and amplitude. These properties are varied in the parametric studies. We find that the amplitude of vertical kink oscillations is significantly amplified in comparison to horizontal kink oscillations for exciters located centrally (symmetrically) below the loop, but not if the exciter is located a significant distance to the side of the loop. This explains why the pure vertical kink mode is so rarely observed in comparison to the horizontally polarized one. We discuss the role of curved magnetic field lines and the pulse overlapping at one of the loop's footpoints in 3-D active regions (AR's) on the excitation and the damping of slow standing waves. We find that footpoint excitation becomes more efficient in 3-D curved loops than in 2-D curved arcades and that slow waves can be excited within an interval of time that is comparable to the observed one wave-period due to the combined effect of the pulse inside and outside the loop. Additionally, we study the effect of AR topology on the excitation and trapping of loop oscillations. We find that a perturbation acting directly on a single loop excites oscillations, but results in an increased leakage compared to excitation of oscillations in an AR field by an external source.

Concerning the Dynamics of Energetic Protons in Coronal Magnetic Loops: Dispersion Effects of Alfven Waves

1985 ◽  
Vol 107 ◽  
pp. 559-559
Author(s):  
V. A. Mazur ◽  
A. V. Stepanov
Keyword(s):  
Magnetic Field ◽  
Wave Dispersion ◽  
Alfven Waves ◽  
Alfven Wave ◽  
Wave Number ◽  
Alfvén Waves ◽  
Coronal Loops ◽  
Coronal Magnetic Loops ◽  
The Magnetic Field ◽  
Solar Coronal

It is shown that the existence of plasma density inhomogeneities (ducts) elongated along the magnetic field in coronal loops, and of Alfven wave dispersion, associated with the taking into account of gyrotropy U ≡ ω/ωi ≪ 1 (Leonovich et al., 1983), leads to the possibility of a quasi-longitudinal k⊥ < √U k‖ propagation (wave guiding) of Alfven waves. Here ω is the frequency of Alfven waves, ωi is the proton gyrofrequency, and k is the wave number. It is found that with the parameter ξ = ω2 R/ωi A > 1, where R is the inhomogeneity scale of a loop across the magnetic field, and A is the Alfven wave velocity, refraction of Alfven waves does not lead, as contrasted to Wentzel's inference (1976), to the waves going out of the regime of quasi-longitudinal propagation. As the result, the amplification of Alfven waves in solar coronal loops can be important. A study is made of the cyclotron instability of Alfven waves under solar coronal conditions.

Repeated Coronal Condensations Caused by Magnetic Reconnection between Solar Coronal Loops

2019 ◽  
Vol 884 (1) ◽  
pp. 34 ◽  
Author(s):  
Leping Li ◽  
Hardi Peter ◽  
Lakshmi Pradeep Chitta ◽  
Jun Zhang ◽  
Jiangtao Su ◽  
...  
Keyword(s):  
Magnetic Reconnection ◽  
Coronal Loops ◽  
Solar Coronal

scholarly journals Self-organized braiding in solar coronal loops

2015 ◽  
Vol 81 (4) ◽  
Author(s):  
M. A. Berger ◽  
M. Asgari-Targhi ◽  
E. E. DeLuca
Keyword(s):  
Coronal Loops ◽  
Frequency Distributions ◽  
Fire Model ◽  
X Ray ◽  
Self Organized ◽  
Forest Fire Model ◽  
Distribution Laws ◽  
Field Lines ◽  
Power Law Distributions ◽  
Solar Coronal

AbstractIn this paper, we investigate the evolution of braided solar coronal loops. We assume that coronal loops consist of several internal strands which twist and braid about each other. Reconnection between the strands leads to small flares and heating of the loop to x-ray temperatures. Using a method of generating and releasing braid structure similar to a forest fire model, we show that the reconnected field lines evolve to a self-organised critical state. In this state, the frequency distributions of coherent braid sequences as well as flare energies follow power law distributions. We demonstrate how the presence of net helicity in the loop alters the distribution laws.

scholarly journals THERMAL NON-EQUILIBRIUM REVEALED BY PERIODIC PULSES OF RANDOM AMPLITUDES IN SOLAR CORONAL LOOPS

2016 ◽  
Vol 827 (2) ◽  
pp. 152 ◽  
Author(s):  
F. Auchère ◽  
C. Froment ◽  
K. Bocchialini ◽  
E. Buchlin ◽  
J. Solomon
Keyword(s):  
Coronal Loops ◽  
Non Equilibrium ◽  
Solar Coronal
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