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Rf driven currents (I(rf)) above 50 kA are observed during electron cyclotron current drive experiments in the DIII-D tokamak. These are the first tokamak experiments combining strong first pass absorption, localised deposition of the rf power, and good confinement of the electrons which carry the rf-generated current. Experimentally, rf waves at 60 GHz, polarised for the extraordinary mode, are launched from the high field side of the tokamak with k(parallel) approx. 2.1 +/- 1.2/cm. A 1D transport code is used to calculate the inductive loop voltage during the ohmic and rf phases, using Spitzer resistivity and including neoclassical effects. For the ohmic phase, very good agreement is obtained between calculated and measured values of the loop voltage. During the rf phase, the difference between the transport code calculation and the experimental loop voltage implies driven currents of over 100 kA. Calculations of I(rf) are obtained by integrating over the distorted electron distribution function and are in agreement with analytical theory. Results from co- vs. counter-injection of the rf, relative to the direction of the total plasma current, demonstrate that I(rf) is driven in a direction consistent with the directed launch of the rf waves.

Additional information

Authors: JAMES R A, Lawrence Livermore National Laboratory, Livermore (US);DE HAAS J, Lawrence Livermore National Laboratory, Livermore (US);GIRUZZI G ET AL., CEA, Département de Recherches sur la Fusion Contrôlée, Saint-Paul-lez-Durance (FR);COX M, AEA Fusion, Culham Laboratory, Abingdon, Oxon. (GB);FYARETDINOV A ET AL., Kurchatov Institute, Moscow (SU);JANZ S, University of Maryland (US);HARVEY R ET AL., General Atomics, San Diego (US)
Bibliographic Reference: Paper presented: 32nd Annual Meeting of the American Physical Society, Division of Plasma Physics, Cincinnati (US), Nov. 12-16, 1990
Availability: Available from (1) as Paper EN 35865 ORA
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