Progress in confinement and stability with plasma shape and profile control for steady-state operation in the Japan Atomic Energy Research Institute Tokamak-60 Upgrade

This paper describes the latest achievements of the Japan Atomic Energy Research Institute Tokamak-60 Upgrade (JT-60U) [H. Kimura and the JT-60 Team, Phys. Plasmas 3, 1943 (1996)] for the establishment of the physics and technology basis for steady-state, fully noninductive current-drive plasmas with high fusion performance. Recent results are highlighted by (1) high performance reversed-magnetic-shear discharges [an idealized equivalent Q(DT) of 1.05, a confinement-enhancement factor (H factor) of 3.23, and a normalized beta value (beta(N)) of 1.88 at I-p=2.8 MA/P-abs=17 MW]; the first observation of thermal transport barriers both for electrons and ions, (2) the first injection of negative-ion-based neutral deuterium beams in the world for studies of current drive, heating, and high-energy particle behavior (achieved so far: 2.5 MW/400 keV, design values: 10 MW/500 keV); high neutralization efficiency of 60% at 370 keV; high current drive efficiency of eta(CD)=8x10(18) m(-2) A/W, (3) improved giant edge-localized-mode (ELM) limit and normalized beta limit by high triangularity (delta) shaping the quasi-steady-state ELMy plasmas with integrated high performance were sustained for 8 times the energy confinement time (delta=0.35, H=2.5, beta(N)=2.5 at I-p=1.5 MA and B-t=3.6 T), and (4) enhanced divertor radiation and detached divertor in reversed-shear discharges with neon puffing, while the internal transport barrier was sustained. (C) 1997 American Institute of Physics.