Progress toward long-pulse high-performance Advanced Tokamak discharges on the DIII-D tokamak
- 20 April 2001
- journal article
- research article
- Published by AIP Publishing in Physics of Plasmas
- Vol. 8 (5), 2208-2216
- https://doi.org/10.1063/1.1355980
Abstract
Significant progress has been made in obtaining high-performance discharges for many energy confinement times in the DIII-D tokamak [J. L. Luxon et al., Plasma Physics and Controlled Fusion Research (International Atomic Energy Agency, Vienna, 1987), Vol. I, p. 159]. Normalized performance (measured by the product of and indicative of the proximity to both conventional β limits and energy confinement quality, respectively) ∼10 has been sustained for >5 with These edge localized modes (ELMing) H-mode discharges have β∼5%, which is limited by the onset of resistive wall modes slightly above the ideal no-wall limit, with approximately 75% of the current driven noninductively. The remaining Ohmic current is localized near the half-radius. The DIII-D electron cyclotron heating system is being upgraded to replace this inductively driven current with localized electron cyclotron current drive (ECCD). Density control, which is required for effective ECCD, has been successfully demonstrated in long-pulse high-performance ELMing H-mode discharges with for up to 6.3 s. In plasma shapes compatible with good density control in the present divertor configuration, the achieved is somewhat less than that in the high discharges.
Keywords
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