Concept
Magnetic helicity
Related publications (34)
Shedding light on the MRI-driven dynamo in a stratified shearing box
We study the magneto-rotational instability (MRI) dynamo in a geometrically thin disc (H/R < 1) using stratified zero net (vertical) flux shearing box simulations. We find that mean fields and electromotive forces (EMFs) oscillate with a primary frequency ...
2024Dissipative magnetic structures and scales in small-scale dynamos
Small-scale dynamos play important roles in modern astrophysics, especially on galactic and extragalactic scales. Owing to dynamo action, purely hydrodynamic Kolmogorov turbulence hardly exists and is often replaced by hydromagnetic turbulence. Understandi ...
OXFORD UNIV PRESS2023Occam's razor on the mechanism of resistive-wall-mode-induced beta limits in diverted tokamaks
Jonathan Graves, Daniele Brunetti
External kink modes, believed to be the drive of the 0-limiting resistive wall mode, are strongly stabilized by the presence of a separatrix. We thus propose a novel mechanism explaining the appearance of long-wavelength global instabilities in free bounda ...
2023Dynamo instabilities in plasmas with inhomogeneous chiral chemical potential
We study the dynamics of magnetic fields in chiral magnetohydrodynamics, which takes into account the effects of an additional electric current related to the chiral magnetic effect in high-energy plasmas. We perform direct numerical simulations, consideri ...
AMER PHYSICAL SOC2022Modeling of saturated external MHD instabilities in tokamaks: A comparison of 3D free boundary equilibria and nonlinear stability calculations
3D free boundary equilibrium computations have recently been used to model external kinks and edge harmonic oscillations (EHOs), comparing with linear MHD stability codes, and nonlinear analytic theory [Kleiner et al., Phys. Plasma Controlled Fusion 61, 08 ...
AIP Publishing2022A non-twisting flux tube for local gyrokinetic simulations
Stephan Brunner, Justin Richard Ball
Local gyrokinetic simulations use a field-aligned domain that twists due to the magnetic shear of the background magnetic equilibrium. However, if the magnetic shear is strong and/or the domain is long, the twist can become so extreme that it fails to prop ...
2021Model for current drive induced crash cycles in W7-X
Joaquim Loizu Cisquella, Ajay Kumar
In the Wendelstein 7-X (W7-X) stellarator, the vacuum rotational transform, ι, has a flat radial profile and does not cross any major rational resonance. Nevertheless, during plasma operation the ι‐profile can be strongly modified by electron cyclotron cur ...
2021Development of free-boundary equilibrium and transport solvers for simulation and real-time interpretation of tokamak experiments
To exploit fusion as a source of energy, a hot and dense confined plasma is needed. This is
achieved in tokamaks by actively controlling the plasma state meaning shape, position and
internal kinetic profiles. This thesis addresses two topics: the developme ...
EPFL2021Chiral fermion asymmetry in high-energy plasma simulations
The chiral magnetic effect (CME) is a quantum relativistic effect that describes the appearance of an additional electric current along a magnetic field. It is caused by an asymmetry between the number densities of left- and right-handed fermions, which ca ...
2020Properties of a new quasi-axisymmetric configuration
A novel, compact, quasi-axisymmetric configuration is presented which exhibits low fast-particle losses and is stable to ideal magnetohydrodynamic (MHD) instabilities. The design has fast-particle loss rates below 8% for flux surfaces within the half-radiu ...
2019