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arXiv · 1203.6455

Zero-Turbulence Manifold in a Toroidal Plasma

E. G. Highcock·A. A. Schekochihin·S. C. Cowley·M. Barnes·F. I. Parra·C. M. Roach·W. Dorland
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Abstract

Sheared toroidal flows can cause bifurcations to zero-turbulent-transport states in tokamak plasmas. The maximum temperature gradients that can be reached are limited by subcritical turbulence driven by the parallel velocity gradient. Here it is shown that q/ε(magnetic field pitch/inverse aspect ratio) is a critical control parameter for sheared tokamak turbulence. By reducing q/ε, far higher temperature gradients can be achieved without triggering turbulence, in some instances comparable to those found experimentally in transport barriers. The zero-turbulence manifold is mapped out, in the zero-magnetic-shear limit, over the parameter space (γ_E, q/ε, R/L_T), where γ_E is the perpendicular flow shear and R/L_T is the normalised inverse temperature gradient scale. The extent to which it can be constructed from linear theory is discussed.

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E. G. Highcock, A. A. Schekochihin, S. C. Cowley, M. Barnes, F. I. Parra, C. M. Roach, W. Dorland. 2012-03-29. Zero-Turbulence Manifold in a Toroidal Plasma. https://doi.org/10.1103/physrevlett.109.265001

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