Transport bifurcation in a rotating tokamak plasma

E. G. Highcock, M. Barnes, A. A. Schekochihin, F. I. Parra, C. M. Roach, S. C. Cowley

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50 Scopus citations

Abstract

The effect of flow shear on turbulent transport in tokamaks is studied numerically in the experimentally relevant limit of zero magnetic shear. It is found that the plasma is linearly stable for all nonzero flow shear values, but that subcritical turbulence can be sustained nonlinearly at a wide range of temperature gradients. Flow shear increases the nonlinear temperature gradient threshold for turbulence but also increases the sensitivity of the heat flux to changes in the temperature gradient, except over a small range near the threshold where the sensitivity is decreased. A bifurcation in the equilibrium gradients is found: for a given input of heat, it is possible, by varying the applied torque, to trigger a transition to significantly higher temperature and flow gradients.

Original languageEnglish (US)
Article number215003
JournalPhysical review letters
Volume105
Issue number21
DOIs
StatePublished - Nov 17 2010

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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