scholarly journals Non-ideal MHD Properties of Photospheric Flux Tubes

2001 ◽  
Vol 203 ◽  
pp. 508-510
Author(s):  
J. Kleimann ◽  
G. Hornig
Keyword(s):  
Magnetic Flux ◽  
Scaling Law ◽  
Small Scale ◽  
Solar Convection Zone ◽  
Flux Tubes ◽  
Solar Convection ◽  
Mhd Equilibria ◽  
Magnetic Flux Tubes ◽  
Pass Through ◽  
Small Scale Structures

Magnetic flux tubes reaching from the solar convection zone into the chromosphere have to pass through the relatively cool, and therefore highly non-ideal (i.e. resistive) photospheric plasma. It is shown that stationary MHD equilibria of magnetic flux tubes which pass through this region require an inflow of plasma into the tube and a deviation from isorotation along the tube axis. Although for characteristic parameters of thick flux tubes the effect is negligible, a scaling law indicates its importance for small-scale structures. The relevance of this inflow for the expansion of flux tubes above the photosphere is discussed.

scholarly journals The Rise of Kink-Unstable Magnetic Flux Tubes in the Solar Convection Zone

1998 ◽  
Vol 505 (1) ◽  
pp. L59-L63 ◽  
Author(s):  
Y. Fan ◽  
E. G. Zweibel ◽  
M. G. Linton ◽  
G. H. Fisher
Keyword(s):  
Magnetic Flux ◽  
Convection Zone ◽  
Solar Convection Zone ◽  
Flux Tubes ◽  
Solar Convection ◽  
Magnetic Flux Tubes

scholarly journals The Small-Scale Photospheric Magnetic Field as an Indicator of the Dynamo

1993 ◽  
Vol 141 ◽  
pp. 143-146
Author(s):  
K. Petrovay ◽  
G. Szakály
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Observational Data ◽  
Convective Zone ◽  
Small Scale ◽  
Dynamo Theory ◽  
Flux Tubes ◽  
Magnetic Flux Tubes ◽  
Surface Fields

AbstractThe presently widely accepted view that the solar dynamo operates near the base of the convective zone makes it difficult to relate the magnetic fields observed in the solar atmosphere to the fields in the dynamo layer. The large amount of observational data concerning photospheric magnetic fields could in principle be used to impose constraints on dynamo theory, but in order to infer these constraints the above mentioned “missing link” between the dynamo and surface fields should be found. This paper proposes such a link by modeling the passive vertical transport of thin magnetic flux tubes through the convective zone.

K-VORTEX DYNAMICS IN $\mathcal{N}\, = \,1^*$ THEORY AND IN ITS GRAVITY DUAL

2010 ◽  
Vol 25 (02n03) ◽  
pp. 247-257
Author(s):  
R. AUZZI
Keyword(s):  
Magnetic Flux ◽  
Scaling Law ◽  
World Sheet ◽  
Flux Tubes ◽  
Yang Mills ◽  
Hooft Coupling ◽  
Higgs Vacuum ◽  
Large N ◽  
Vortex Solutions ◽  
Magnetic Flux Tubes

We study magnetic flux tubes in the Higgs vacuum of the [Formula: see text] mass deformation of SU(Nc), [Formula: see text] SYM and its large Nc string dual, the Polchinski-Strassler geometry. Choosing equal masses for the three adjoint chiral multiplets, for all Nc we identify a "colour-flavour locked" symmetry, SO(3)C+F which leaves the Higgs vacuum invariant. At weak coupling, we find explicit non-Abelian k-vortex solutions carrying a ℤNc-valued magnetic flux, with topological winding 0 < k < Nc. These k-strings spontaneously break SO(3)C+F to U(1)C+F resulting in an S2 moduli space of solutions. The world-sheet sigma model is a nonsupersymmetric ℂℙ1 model with a theta angle θ1+1 = k(Nc - k)θ3+1 where θ3+1 is the Yang-Mills vacuum angle. We find numerically that k-vortex tensions follow the Casimir scaling law Tk ∝ k(Nc - k) for large Nc. In the large Nc IIB string dual, the SO(3)C+F symmetry is manifest in the geometry interpolating between AdS5 × S5 and the interior metric due to a single D5 -brane carrying D3 -brane charge. We identify candidate k-vortices as expanded probe D3 -branes formed from a collection of k D -strings. The resulting k-vortex tension exhibits precise Casimir scaling, and the effective world-sheet theta angle matches the semiclassical result. S -duality maps the Higgs to the confining phase so that confining string tensions at strong 't Hooft coupling also exhibit Casimir scaling in [Formula: see text] theory in the large Nc limit.

scholarly journals Theoretical Models of Magnetic Flux Tubes: Structure and Dynamics

1994 ◽  
Vol 154 ◽  
pp. 407-421
Author(s):  
O Steiner
Keyword(s):  
Magnetic Flux ◽  
Line Emission ◽  
Theoretical Models ◽  
Small Scale ◽  
Solar Photosphere ◽  
Model Calculations ◽  
Flux Tubes ◽  
Wide Range ◽  
Magnetic Flux Tubes ◽  
Lower Chromosphere

Two types of model calculations for small scale magnetic flux tubes in the solar atmosphere are reviewed. In the first kind, one follows the temporal evolution governed by the complete set of the MHD and radiative transfer equations to a (quasi) stationary solution. From such a solution the continuum contrasts of a photospheric flux tube in the visible and in the infrared continuum at 1.6 μm have been computed and are briefly discussed. The second, more empirical type of method assumes the flux tubes to be in magnetohydrostatic equilibrium. It is computationally faster and more flexible and allows us to explore a wide range of parameters. Models and insights obtained from such parameter studies are discussed in some detail. These include an explanation for the peculiar variation of the area asymmetry of Stokes V profiles across the solar disk in terms of mass motions in the surroundings of magnetic flux tubes.Furthermore, a two-dimensional model of the lower chromosphere that has been developed is presented. Emphasis is laid on the effect of thermal bifurcation of the lower chromosphere on the structure of the chromospheric magnetic field. If the cool carbon monoxide clouds, observed in the infrared, occupy the non-magnetic regions, the flux tubes expand very strongly and form a magnetic canopy with an almost horizontal base. This has consequences for the spatial distribution of the Ca II K spectral line emission.Finally, some consideration is given to the formation and destruction of intense magnetic flux tubes in the solar photosphere. The formation is described as a consequence of the flux expulsion process that leads to a convective instability. A possible observational signature of this mechanism is proposed.

scholarly journals Multi-scale dynamics of magnetic flux tubes and inverse magnetic energy transfer

2020 ◽  
Vol 86 (4) ◽  
Author(s):  
Muni Zhou ◽  
Nuno F. Loureiro ◽  
Dmitri A. Uzdensky
Keyword(s):  
Magnetic Flux ◽  
Time Evolution ◽  
Magnetic Energy ◽  
Numerical Study ◽  
Three Dimensional ◽  
Early Time ◽  
Small Scale ◽  
Flux Tubes ◽  
Seed Field ◽  
Magnetic Flux Tubes

We report on an analytical and numerical study of the dynamics of a three-dimensional array of identical magnetic flux tubes in the reduced-magnetohydrodynamic description of the plasma. We propose that the long-time evolution of this system is dictated by flux-tube mergers, and that such mergers are dynamically constrained by the conservation of the pertinent (ideal) invariants, viz. the magnetic potential and axial fluxes of each tube. We also propose that in the direction perpendicular to the merging plane, flux tubes evolve in a critically balanced fashion. These notions allow us to construct an analytical model for how quantities such as the magnetic energy and the energy-containing scale evolve as functions of time. Of particular importance is the conclusion that, like its two-dimensional counterpart, this system exhibits an inverse transfer of magnetic energy that terminates only at the system scale. We perform direct numerical simulations that confirm these predictions and reveal other interesting aspects of the evolution of the system. We find, for example, that the early time evolution is characterized by a sharp decay of the initial magnetic energy, which we attribute to the ubiquitous formation of current sheets. We also show that a quantitatively similar inverse transfer of magnetic energy is observed when the initial condition is a random, small-scale magnetic seed field.

Emergence of undulatory magnetic flux tubes by small scale reconnections

2006 ◽  
Vol 38 (5) ◽  
pp. 902-905 ◽  
Author(s):  
E. Pariat ◽  
G. Aulanier ◽  
B. Schmieder ◽  
M.K. Georgoulis ◽  
D.M. Rust ◽  
...  
Keyword(s):  
Magnetic Flux ◽  
Small Scale ◽  
Flux Tubes ◽  
Magnetic Flux Tubes
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