(IT/P1-5) Transport Physics of Hybrid Scenario Plasmas in the International Multi-Tokamak Database and Implications for ITER

R.V. Budny1), C.E. Kessel1), J.E. Kinsey2), F. Imbeaux3), I. Voitsekhovitch4), J. Candy5), R.E. Waltz5), T. Fujita6), C. Greenfield5), M. Murakami7), A.C.C. Sips8), W. Houlberg7), E. Doyle9)
1) Princeton University Princeton Plasma Physics Laboratory, Princeton NJ 08543, USA
2) Lehigh University, Bethlehem, PA 18015, USA
3) Association EURATOM-CEA, Cadarache F-13108 Saint-Paul-lez-Durance Cedex, FR
4) EURATOM/UKAEA Fusion Association, Culham Science Center, Abingdon, OX14 3DB, UK
5) General Atomics, PO Box 85608, San Diego, CA 92186, USA
6) Naka Fusion Research Establishment, Japan Atomic Energy Research Instiute, Nakamachi, Naka-gun, Ibaraki-ken 311-0193, JP
7) Oak Ridge National Laboratory, Oak Ridge, TN, USA
6) Max-Planck-Institute fur Plasmahysik, EURATOM-IPP Association, Garching, GDR
9) University of California, Los Angeles, CA, USA

Abstract.  Turbulence induced transport coefficients are calculated using the GYRO gyrokinetic turbulence simulation code for Hybrid plasmas contained in the international ITPA profile database. Hybrid plasmas address the ITER long pulse, high fluence mission. Common features are central safety factors near or above unity, with sustained stationary high βn, high confinement, and reduced inductive current relative to standard H-mode plasmas of equivalent fusion performance. Credible prediction of ITER hybrid performance depends on the successful application of simulation codes on existing experiments. A key conclusion of this work is that off diagonal elements in the transport matrix strongly affect energy, particle and momentum transport. This runs counter to the conventional approach of existing predictive models which rely on dominant diagonal transport coefficients. Implications for ITER simulation studies and directions for future investigation are also presented. The nonlinear GYRO studies are used to compute the changes in the transport coefficients χj≡{χmain, χimp, χe, Dmain, Dimp, De, χmomentum} resulting from varying the drive/damping terms dk≡{a/LTmain, a/LTimp, a/LTe, a/Lnmain, a/Lnimp, a/Lne, Tmain/Te, γE×B/γ0} from their measured values by ±20%. The subscripts ``main'' and ``imp'' refer to the bulk and effective impurity ion species, both treated kinetically, γE×B is the E×B flow shearing rate, and γ0 is its value inferred from measurements. These results give a 7×8 matrix estimating χj/∂dk. Besides the usual diagonal terms, many of the off-diagonal terms have significant and complicated contributions to the transport. Examples of results for one of the JET hybrid plasmas averaged over the region r/a between 0.4 and 0.8 indicates that χmain is driven mainly by a/LTmain and damped mainly by Tmain/Te; χe is driven mainly by a/LTmain and a/Lnmain; De is damped by a/LTe and a/LTmain, and increased by a/Lne and Tmain/Te; and Dimp is driven by a/LTmain, a/LTe, a/Lnmain, a/Lnimp, and damped by Tmain/Te.

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