scholarly journals On the Relationship between Equilibrium Bifurcations and Ideal MHD Instabilities for Line-Tied Coronal Loops

Solar Physics ◽  
2009 ◽  
Vol 261 (1) ◽  
pp. 87-106 ◽  
Author(s):  
T. Neukirch ◽  
Z. Romeou
Keyword(s):  
Coronal Loops ◽  
Mhd Instabilities ◽  
Ideal Mhd ◽  
The Relationship

scholarly journals Can Multi-threaded Flux Tubes in Coronal Arcades Support a Magnetohydrodynamic Avalanche?

Solar Physics ◽  
2021 ◽  
Vol 296 (8) ◽  
Author(s):  
J. Threlfall ◽  
J. Reid ◽  
A. W. Hood
Keyword(s):  
Magnetic Fields ◽  
Three Dimensional ◽  
Coronal Loops ◽  
Flux Tubes ◽  
Single Thread ◽  
Mhd Instabilities ◽  
Mhd Instability ◽  
Mhd Simulations ◽  
Ideal Mhd ◽  
Model Geometry

AbstractMagnetohydrodynamic (MHD) instabilities allow energy to be released from stressed magnetic fields, commonly modelled in cylindrical flux tubes linking parallel planes, but, more recently, also in curved arcades containing flux tubes with both footpoints in the same photospheric plane. Uncurved cylindrical flux tubes containing multiple individual threads have been shown to be capable of sustaining an MHD avalanche, whereby a single unstable thread can destabilise many. We examine the properties of multi-threaded coronal loops, wherein each thread is created by photospheric driving in a realistic, curved coronal arcade structure (with both footpoints of each thread in the same plane). We use three-dimensional MHD simulations to study the evolution of single- and multi-threaded coronal loops, which become unstable and reconnect, while varying the driving velocity of individual threads. Experiments containing a single thread destabilise in a manner indicative of an ideal MHD instability and consistent with previous examples in the literature. The introduction of additional threads modifies this picture, with aspects of the model geometry and relative driving speeds of individual threads affecting the ability of any thread to destabilise others. In both single- and multi-threaded cases, continuous driving of the remnants of disrupted threads produces secondary, aperiodic bursts of energetic release.

WKB estimates for the onset of ideal MHD instabilities in solar coronal loops

Solar Physics ◽  
1994 ◽  
Vol 150 (1-2) ◽  
pp. 99-115 ◽  
Author(s):  
A. W. Hood ◽  
P. De Bruyne ◽  
R. A. M. Van Der Linden ◽  
M. Goossens
Keyword(s):  
Coronal Loops ◽  
Mhd Instabilities ◽  
Ideal Mhd ◽  
Solar Coronal

scholarly journals Ideal MHD instabilities for coronal mass ejections: interacting current channels and particle acceleration

2019 ◽  
Vol 3 (1) ◽  
Author(s):  
Rony Keppens ◽  
Yang Guo ◽  
Kirit Makwana ◽  
Zhixing Mei ◽  
Bart Ripperda ◽  
...  
Keyword(s):  
Particle Acceleration ◽  
Coronal Mass Ejections ◽  
Mhd Instabilities ◽  
Ideal Mhd

The beta limit in the Advanced Toroidal Facility due to local ideal MHD instabilities

1989 ◽  
Vol 29 (4) ◽  
pp. 617-627 ◽  
Author(s):  
W.A. Cooper ◽  
S.P. Hirshman ◽  
D.K. Lee
Keyword(s):  
Mhd Instabilities ◽  
Ideal Mhd

Energy absorption in the continuous spectrum of ideal MHD

1975 ◽  
Vol 13 (1) ◽  
pp. 87-105 ◽  
Author(s):  
J. A. Tataronis
Keyword(s):  
Energy Absorption ◽  
Current Source ◽  
Alfven Wave ◽  
Spatial Gradients ◽  
Enhanced Absorption ◽  
Ideal Mhd ◽  
Continuous Frequency ◽  
The Relationship ◽  
Plasma Profile ◽  
The Continuum

The relationship between energy absorption and the continuous frequency spectrum of the linearized equations of ideal MHD is investigated. We limit ourselves to incompressible fluid perturbations for which the continuum stems from resonant surfaces where the oscillation frequency equals the local frequency of an Alfvén wave. Details of this absorption process are illustrated by obtaining the response of the diffuse sheet pinch to an external current source. Expressions are derived that give the rate at which energy is transferred to the plasma, and show the spatial distribution of the absorbed energy. The results indicate that the absorption is enhanced if the plasma profile has regions of large spatial gradients. This enhanced absorption is a consequence of the presence of surface waves.

scholarly journals Magnetic Equilibria and Instabilities

1989 ◽  
Vol 104 (1) ◽  
pp. 347-360
Author(s):  
Takashi Sakurai
Keyword(s):  
Solar Flares ◽  
Multiple Solutions ◽  
Magnetic Energy ◽  
Slow Phase ◽  
Two Dimensional ◽  
Explosive Energy ◽  
Mhd Instabilities ◽  
Ideal Mhd ◽  
Slow Evolution ◽  
Equilibrium Sequence

AbstractSolar flares are understood as a process of explosive liberation of magnetic energy, coming after a slow phase of energy build-up. The slow evolution of magnetic equilibria may end up with (a) the termination of an equilibrium sequence, or (b) an instability. The distinction between the two can be made by drawing schematic potential curves. Case (a) has been extensively studied in two-dimensional models. The appearance of multiple solutions, or disappearance of a solution takes place as the system evolves away from the current-free configuration. Case (b) can be discussed in terms of ideal MHD or resistive MHD instabilities. A possible route to explosive energy release is suggested by combining these two cases.

Ideal MHD Instabilities with Finite β-Effect in Reversed Field Pinch

1989 ◽  
Vol 58 (2) ◽  
pp. 473-481 ◽  
Author(s):  
Akihide Fujisawa ◽  
Shori Onodera ◽  
Kenro Miyamoto
Keyword(s):  
Reversed Field Pinch ◽  
Mhd Instabilities ◽  
Ideal Mhd ◽  
Reversed Field

scholarly journals No unique solution to the seismological problem of standing kink magnetohydrodynamic waves

2019 ◽  
Vol 622 ◽  
pp. A44 ◽  
Author(s):  
I. Arregui ◽  
M. Goossens
Keyword(s):  
Bayesian Inference ◽  
Unique Solution ◽  
Coronal Loops ◽  
Magnetohydrodynamic Waves ◽  
Mathematical Arguments ◽  
Equilibrium Profiles ◽  
The Relationship ◽  
Insight Into

The aim of this paper is to point out that the classic seismological problem using observations and theoretical expressions for the periods and damping times of transverse standing magnetohydrodynamic waves in coronal loops is better referred to as a reduced seismological problem. “Reduced” emphasises the fact that only a small number of characteristic quantities of the equilibrium profiles can be determined. Reduced also implies that there is no unique solution to the full seismological problem. Even the reduced seismological problem does not allow a unique solution. Bayesian inference results support our mathematical arguments and offer insight into the relationship between the algebraic and the probabilistic inversions.

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