부산대학교 도서관

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 β[sub N]H[sub 89] and indicative of the proximity to both conventional β limits and energy confinement quality, respectively) ∼10 has been sustained for >5 τ[sub E] with q[sub min] > 1.5. These edge localized modes (ELMing) H-mode discharges have &beta∼5%, which is limited by the onset of resistive wall modes slightly above the ideal no-wall n = 1 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 &beta[sub N]H[sub 89]∼ 7 for up to 6.3 s. In plasma shapes compatible with good density control in the present divertor configuration, the achieved β[sub N] is somewhat less than that in the high β[sub N]H[sub 89] = 10 discharges. © 2001 American Institute of Physics. [DOI: 10.1063/1. [ABSTRACT FROM AUTHOR]