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(EXP1/14) Unifying Role of Radial Electric Field Shear in the Confinement Trends of Transitionless Regimes in TFTR

(This paper was rapporteured in lecture EX5/3)

D. R. Ernst, S. Batha¹, M. Beer, M. G. Bell, R. E. Bell, R. V. Budny, B. Coppi², W. Dorland³, P. C. Efthimion, T. S. Hahm, G. W. Hammett, R. J. Hawryluk, K. W. Hill, M. Kotschenreuther⁴, F. M. Levinton¹, Z. Lin, D. K. Mansfield, R. Nazikian, M. Porkolab², G. Rewoldt, S. D. Scott, E. J. Synakowski, M. C. Zarnstorff and the TFTR Team

Princeton Plasma Physics Laboratory, Princeton, New Jersey, USA
¹ Fusion Physics and Technology Inc., Torrance, California USA
² Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
³ University of Maryland, College Park, Maryland, USA
⁴ Institute for Fusion Studies, University of Texas-Austin, Texas, USA

Abstract.  Turbulence suppression by radial electric field shear ( E_r) is shown to be important in the enhanced confinement of TFTR supershot plasmas. Simulations of supershot ion temperature profiles are performed using an existing parameterization of transport due to toroidal ion temperature gradient modes, extended to include suppression by E_r shear. New spectroscopic measurements of E_r differ significantly from prior neoclassical estimates. Supershot temperature profiles appear to be consistent with a criterion describing near-complete turbulence suppression by intrinsically generated E_r shear. Helium spoiling and xenon puffing experiments are simulated to illustrate the role of E_r shear in the confinement changes observed.

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