scholarly journals Proof of Taylor’s Conjecture on Magnetic Helicity Conservation

2019 ◽  
Vol 373 (2) ◽  
pp. 707-738 ◽  
Author(s):  
Daniel Faraco ◽  
Sauli Lindberg
Keyword(s):  
Magnetic Helicity ◽  
Helicity Conservation

scholarly journals The magnetic helicity density patterns from non-axisymmetric solar dynamo

2021 ◽  
Vol 87 (1) ◽  
Author(s):  
Valery V. Pipin
Keyword(s):  
Magnetic Field ◽  
Differential Rotation ◽  
Conservation Law ◽  
Large Scale ◽  
Solar Dynamo ◽  
Magnetic Helicity ◽  
Dynamo Model ◽  
Density Distributions ◽  
Large Scale Magnetic Field ◽  
Helicity Conservation

We study the helicity density patterns which can result from the emerging bipolar regions. Using the relevant dynamo model and the magnetic helicity conservation law we find that the helicity density patterns around the bipolar regions depend on the configuration of the ambient large-scale magnetic field, and in general they show a quadrupole distribution. The position of this pattern relative to the equator can depend on the tilt of the bipolar region. We compute the time–latitude diagrams of the helicity density evolution. The longitudinally averaged effect of the bipolar regions shows two bands of sign for the density distributions in each hemisphere. Similar helicity density patterns are provided by the helicity density flux from the emerging bipolar regions subjected to surface differential rotation.

Relation between the magnetic free energy and relative magnetic helicity in the MHD extreme state of solar corona

2020 ◽  
Author(s):  
Shangbin Yang ◽  
Joerg Buechner ◽  
Hongqi Zhang
Keyword(s):  
Magnetic Field ◽  
Free Energy ◽  
Solar Activity ◽  
Solar Corona ◽  
Solar Flares ◽  
Magnetic Helicity ◽  
Magnetic Free Energy ◽  
Helicity Conservation ◽  
Field Lines ◽  
Extreme State

<p>Magnetic helicity is a quantity describing the twist, writhe, and torsion of magnetic field lines and magnetic configurations . The concept of magnetic helicity has successfully been applied to characterize solar coronal processes. A conjecture about one approximation relation between free magnetic free energy and relative magnetic helicity in the MHD extreme state of solar corona has been proposed by using the concept of magnetic helicity conservation and Lie-Poisson mechanical structure of MHD. We use constant α force-free filed extrapolation to check out this relation. We also apply this relation to analyze the results from the simulations and observations. Such relation may be helpful to predict the solar activity like the solar flares and CMEs</p>

scholarly journals Magnetic Helicity Conservation

2005 ◽  
Vol 13 ◽  
pp. 85-88 ◽  
Author(s):  
Mitchell A. Berger
Keyword(s):  
Interplanetary Space ◽  
Energy State ◽  
Minimum Energy ◽  
Free Field ◽  
Space Physics ◽  
Magnetic Clouds ◽  
Magnetic Helicity ◽  
Dynamo Theory ◽  
Mhd Turbulence ◽  
Helicity Conservation

AbstractMagnetic Helicity measures basic structural properties of magnetic fields such as twist, shear, linking, writhe, and handedness. It is conserved in ideal MHD and approximately conserved during reconnection. The minimum energy state of a field with a given magnetic helicity is a linear force free field. Helicity plays an important role in MHD turbulence and dynamo theory, and provides a valuable observational tool in solar and space physics. Helicity conservation can be tracked from the solar dynamo to active regions to coronal mass ejections to magnetic clouds in interplanetary space.

scholarly journals From convective to stellar dynamos

2010 ◽  
Vol 6 (S271) ◽  
pp. 279-287 ◽  
Author(s):  
Axel Brandenburg ◽  
Petri J. Käpylä ◽  
Maarit J. Korpi
Keyword(s):  
Magnetic Fields ◽  
Time Scale ◽  
Large Scale ◽  
Magnetic Helicity ◽  
Turbulent Eddies ◽  
Helicity Conservation

AbstractConvectively driven dynamos with rotation generating magnetic fields on scales large compared with the scale of the turbulent eddies are being reviewed. It is argued that such fields can be understood as the result of an α effect. Simulations in Cartesian domains show that such large-scale magnetic fields saturate on a time scale compatible with the resistive one, suggesting that the magnitude of the α effect is here still constrained by approximate magnetic helicity conservation. It is argued that, in the absence of shear and/or any other known large-scale dynamo effects, these simulations prove the existence of turbulent α2-type dynamos. Finally, recent results are discussed in the context of solar and stellar dynamos.

scholarly journals Testing magnetic helicity conservation in a solar-like active event

2015 ◽  
Vol 580 ◽  
pp. A128 ◽  
Author(s):  
E. Pariat ◽  
G. Valori ◽  
P. Démoulin ◽  
K. Dalmasse
Keyword(s):  
Magnetic Helicity ◽  
Helicity Conservation

scholarly journals A Check for Consistency between Different Magnetic Helicity Measurements Based on the Helicity Conservation Principle

2007 ◽  
Vol 656 (2) ◽  
pp. 1167-1172 ◽  
Author(s):  
Eun‐Kyung Lim ◽  
Hyewon Jeong ◽  
Jongchul Chae ◽  
Yong‐Jae Moon
Keyword(s):  
Magnetic Helicity ◽  
Conservation Principle ◽  
Helicity Conservation
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