Magnetic shear due to localized toroidal flow shear in tokamaks

Jungpyo Lee, Antoine Cerfon

Research output: Contribution to journalArticle

Abstract

We investigate the impact of toroidal rotation on axisymmetric MHD equilibria analytically and numerically, with a focus on the change of the safety factor and magnetic shear induced by the flow. When the toroidal rotation is radially localized by an external momentum source, the pressure due to the flow can change the magnetic configuration and the safety factor significantly, even for subsonic flows. Specifically, when the radial profile of the safety factor is not conserved throughout a discharge, toroidal flow can lead to magnetic shear reversal for the equilibrium magnetic field, and we find that the magnitude of the negative shear is amplified for cross sections with large negative triangularity. This has implications for both magnetohydrodynamic stability and anomalous transport. Furthermore, even when the magnetic flux is conserved and the radial magnetic shear profile does not change, the toroidal flow can modify the local magnetic shear. The poloidal variations of the local magnetic shear due to the flow can stabilize magnetohydrodynamic ballooning modes.

Original languageEnglish (US)
Article number105007
JournalPlasma Physics and Controlled Fusion
Volume61
Issue number10
DOIs
StatePublished - Sep 4 2019

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Safety factor
Shear flow
Magnetohydrodynamics
shear flow
shear
safety factors
Subsonic flow
Magnetic flux
toroidal discharge
Momentum
Magnetic fields
subsonic flow
ballooning modes
magnetohydrodynamic stability
profiles
magnetohydrodynamics
magnetic flux
momentum
cross sections
configurations

Keywords

  • magnetic shear
  • MHD equilibrium
  • plasma equilibrium shape
  • tokamak
  • toroidal rotation

ASJC Scopus subject areas

  • Nuclear Energy and Engineering
  • Condensed Matter Physics

Cite this

Magnetic shear due to localized toroidal flow shear in tokamaks. / Lee, Jungpyo; Cerfon, Antoine.

In: Plasma Physics and Controlled Fusion, Vol. 61, No. 10, 105007, 04.09.2019.

Research output: Contribution to journalArticle

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