Effect of the Shafranov shift and the gradient of β on intrinsic momentum transport in up-down asymmetric tokamaks

Justin Ball, Felix I. Parra, Jungpyo Lee, Antoine Cerfon

Research output: Contribution to journalArticle

Abstract

Tokamaks with up-down asymmetric poloidal cross-sections spontaneously rotate due to turbulent transport of momentum. In this work, we investigate the effect of the Shafranov shift on this intrinsic rotation, primarily by analyzing tokamaks with tilted elliptical flux surfaces. By expanding the Grad-Shafranov equation in the large aspect ratio limit we calculate the magnitude and direction of the Shafranov shift in tilted elliptical tokamaks. The results show that, while the Shafranov shift becomes updown asymmetric and depends strongly on the tilt angle of the flux surfaces, it is insensitive to the shape of the current and pressure profiles (when the geometry, total plasma current, and average pressure gradient are kept fixed). Next, local nonlinear gyrokinetic simulations of these MHD equilibria are performed with GS2, which reveal that the Shafranov shift can significantly enhance the momentum transport. However, to be consistent, the effect of β′ (i.e. the radial gradient of β) on the magnetic equilibrium was also included, which was found to significantly reduce momentum transport. Including these two competing effects broadens the rotation profile, but leaves the on-axis value of the rotation roughly unchanged. Consequently, the shape of the β profile has a significant effect on the rotation profile of an up-down asymmetric tokamak.

Original languageEnglish (US)
Article number125015
JournalPlasma Physics and Controlled Fusion
Volume58
Issue number12
DOIs
StatePublished - Nov 3 2016

Fingerprint

Momentum
momentum
gradients
shift
profiles
Fluxes
plasma currents
Magnetohydrodynamics
Pressure gradient
pressure gradients
leaves
aspect ratio
Aspect ratio
Plasmas
Geometry
cross sections
geometry
simulation

Keywords

  • gyrokinetic simulations
  • magnetohydrodynamics
  • plasma turbulence
  • tokamaks
  • transport properties

ASJC Scopus subject areas

  • Nuclear Energy and Engineering
  • Condensed Matter Physics

Cite this

Effect of the Shafranov shift and the gradient of β on intrinsic momentum transport in up-down asymmetric tokamaks. / Ball, Justin; Parra, Felix I.; Lee, Jungpyo; Cerfon, Antoine.

In: Plasma Physics and Controlled Fusion, Vol. 58, No. 12, 125015, 03.11.2016.

Research output: Contribution to journalArticle

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