Interplay of the magnetic and current density field topologies in axisymmetric devices for magnetic confinement fusion - Laboratoire de Physique des Plasmas (LPP)
Journal Articles Journal of Plasma Physics Year : 2024

Interplay of the magnetic and current density field topologies in axisymmetric devices for magnetic confinement fusion

Abstract

In magnetic confinement fusion devices close to axisymmetry, such as tokamaks, a key element is the winding profile of the magnetic field lines, or its inverse, the safety profile $q=q_{\mathbf{B}}$. A corresponding profile, $q_{\mathbf{J}}$, can be defined for the current density field lines. Amp\`{e}re's law relates any mode of current perturbation $\delta \mathbf{J}_{m,n}$ with a mode of magnetic perturbation $\delta \mathbf{B}_{m,n}$. It is shown that the knowledge of the pair $(q_{\mathbf{B}},q_{\mathbf{J}})$ allows then to characterize the resonant, or non-resonant, nature of the modes for both the magnetic and current density field lines. The expression of $q_{\mathbf{J}}$ in flux coordinate is derived. Including this calculation in the real-time Grad-Shafranov equilibrium reconstruction codes would yield a comprehensive view of the magnetics. The monitoring of the pair $(q_{\mathbf{B}},q_{\mathbf{J}})$ would then allow investigating the role played by the resonant modes for the current density, that are current filamentary modes, in the plasma small-scale turbulence. By driving the magnetic and current density profiles apart so that the images of $q_{\mathbf{B}}$ and $q_{\mathbf{J}}$ are disjoint, these filamentary modes would not impact the magnetic field topology, being not associated to magnetic islands but to non-resonant magnetic modes. It remains to be explored to which extent such a configuration, where the spectrum of tiny current density filaments produces a spectrum of magnetic modes that has practically no effect on heat transport, is beneficial.
Fichier principal
Vignette du fichier
UnderReview31Mai2024.pdf (19.66 Mo) Télécharger le fichier
Origin Files produced by the author(s)

Dates and versions

hal-04623787 , version 1 (25-06-2024)

Identifiers

  • HAL Id : hal-04623787 , version 1

Cite

Marie-Christine Firpo. Interplay of the magnetic and current density field topologies in axisymmetric devices for magnetic confinement fusion. Journal of Plasma Physics, inPress. ⟨hal-04623787⟩
107 View
14 Download

Share

More