scholarly journals On the Inverse Cascade of Magnetic Helicity

2006 ◽  
Vol 640 (1) ◽  
pp. 335-343 ◽  
Author(s):  
Alexandros Alexakis ◽  
Pablo D. Mininni ◽  
Annick Pouquet
Keyword(s):  
Magnetic Helicity ◽  
Inverse Cascade

Inverse cascade in simulated MHD turbulence driven by small scale source of magnetic helicity

2016 ◽  
Vol 52 (1) ◽  
pp. 261-268
Author(s):  
R. Stepanov ◽  
◽  
V. Titov ◽  
◽  
Keyword(s):  
Magnetic Helicity ◽  
Small Scale ◽  
Mhd Turbulence ◽  
Inverse Cascade

scholarly journals Helical mode interactions and spectral transfer processes in magnetohydrodynamic turbulence

2016 ◽  
Vol 791 ◽  
pp. 61-96 ◽  
Author(s):  
Moritz Linkmann ◽  
Arjun Berera ◽  
Mairi McKay ◽  
Julia Jäger
Keyword(s):  
Energy Transfer ◽  
Magnetic Fields ◽  
Magnetic Helicity ◽  
Asymmetric Effect ◽  
Mhd Turbulence ◽  
Dynamo Action ◽  
Reverse Transfer ◽  
Transfer Processes ◽  
Inverse Cascade ◽  
Mode Interactions

Spectral transfer processes in homogeneous magnetohydrodynamic (MHD) turbulence are investigated analytically by decomposition of the velocity and magnetic fields in Fourier space into helical modes. Steady solutions of the dynamical system which governs the evolution of the helical modes are determined, and a stability analysis of these solutions is carried out. The interpretation of the analysis is that unstable solutions lead to energy transfer between the interacting modes while stable solutions do not. From this, a dependence of possible interscale energy and helicity transfers on the helicities of the interacting modes is derived. As expected from the inverse cascade of magnetic helicity in 3-D MHD turbulence, mode interactions with like helicities lead to transfer of energy and magnetic helicity to smaller wavenumbers. However, some interactions of modes with unlike helicities also contribute to an inverse energy transfer. As such, an inverse energy cascade for non-helical magnetic fields is shown to be possible. Furthermore, it is found that high values of the cross-helicity may have an asymmetric effect on forward and reverse transfer of energy, where forward transfer is more quenched in regions of high cross-helicity than reverse transfer. This conforms with recent observations of solar wind turbulence. For specific helical interactions the relation to dynamo action is established. The present analysis provides new theoretical insights into physical processes where inverse cascade and dynamo action are involved, such as the evolution of cosmological and astrophysical magnetic fields and laboratory plasmas.

scholarly journals Inverse cascade of magnetic helicity in magnetohydrodynamic turbulence

2012 ◽  
Vol 85 (1) ◽  
Author(s):  
Wolf-Christian Müller ◽  
Shiva Kumar Malapaka ◽  
Angela Busse
Keyword(s):  
Magnetic Helicity ◽  
Magnetohydrodynamic Turbulence ◽  
Inverse Cascade

scholarly journals The Solar Dynamo: Old, Recent, and New Problems

2001 ◽  
Vol 203 ◽  
pp. 144-151
Author(s):  
A. Brandenburg
Keyword(s):  
Numerical Simulations ◽  
Mean Field ◽  
Direct Numerical Simulations ◽  
Solar Dynamo ◽  
Magnetic Helicity ◽  
Current Status ◽  
Dynamo Theory ◽  
Inverse Cascade ◽  
Mean Field Dynamo ◽  
Stellar Dynamo

A number of problems of solar and stellar dynamo theory are briefly reviewed and the current status of possible solutions is discussed. Results of direct numerical simulations are described in view of mean-field dynamo theory and the relation between the α-effect and the inverse cascade of magnetic helicity is highlighted. The possibility of ‘catastrophic’ quenching of the α-effect is explained in terms of the constraint placed by the conservation of magnetic helicity.

Solar Filaments as Tracers of Subsurface Processes

2000 ◽  
Vol 179 ◽  
pp. 177-183
Author(s):  
D. M. Rust
Keyword(s):  
Magnetic Fields ◽  
Magnetic Flux ◽  
Coronal Mass Ejections ◽  
Interplanetary Space ◽  
Intermediate Stage ◽  
Coronal Plasma ◽  
Magnetic Helicity ◽  
The Sun ◽  
New Paradigm ◽  
Solar Filaments

AbstractSolar filaments are discussed in terms of two contrasting paradigms. The standard paradigm is that filaments are formed by condensation of coronal plasma into magnetic fields that are twisted or dimpled as a consequence of motions of the fields’ sources in the photosphere. According to a new paradigm, filaments form in rising, twisted flux ropes and are a necessary intermediate stage in the transfer to interplanetary space of dynamo-generated magnetic flux. It is argued that the accumulation of magnetic helicity in filaments and their coronal surroundings leads to filament eruptions and coronal mass ejections. These ejections relieve the Sun of the flux generated by the dynamo and make way for the flux of the next cycle.

Magnetic helicity in non-axisymmetric mean-field dynamo

2016 ◽  
Vol 52 (1) ◽  
pp. 145-154
Author(s):  
V. V. Pipin ◽  
Keyword(s):  
Mean Field ◽  
Magnetic Helicity ◽  
Mean Field Dynamo
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