Regimes of improved confinement and stability in DIII-D obtained through current profile modifications

Conference · Tue Sep 01 04:00:00 EDT 1992

OSTI ID:6889189

Lao, L L; Ferron, J R; Taylor, T S; Chan, V S; Osborne, T H; Burrell, K H; Chu, M S; DeBoo, J C; Greenfield, C M; Groebner, R J; Jackson, G L; John, H; Strait, E J; Thompson, S J; Turnbull, A D ^[1]; Doyle, E J; Rettig, C ^[2]; James, R; Wroblewski, D ^[3]

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1. General Atomics, San Diego, CA (United States)
2. California Univ., Los Angeles, CA (United States)
3. Lawrence Livermore National Lab., CA (United Sta

Several regimes of improved confinement and stability have been obtained in recent experiments in the DIII-D tokamak by dynamically varying the toroidal current density profile to transiently produce a poloidal magnetic field profile with more favorable confinement and stability properties. A very peaked current density profile with high plasma internal inductance, [ell][sub i], is produced either by a rapid change in the plasma poloidal cross section or by a rapid change in the total plasma current. Values of thermal energy confinement times nearly 1.8 times the JET/DIII-D ELM-free H-mode thermal confinement scaling are obtained. The confinement enhancement factor over the ITER89-P L-mode confinement scaling, H, is as high as 3. Normalized toroidal beta, [beta][sub N], greater than 6%-m-T/MA and values of the product [beta][sub N]H greater than 15 have also been obtained. Both the confinement and the maximum achievable [beta] vary with [ell][sub i] and decrease as the current profile relaxes. For strongly shaped H-mode discharges, in addition to the current density profile peakedness, as measured by [ell][sub i] other current profile parameters, such as its distribution near the edge region, may also affect the confinement enhancement.

• Research Organization: General Atomics, San Diego, CA (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC03-89ER51114; AC05-84OR21400; W-7405-ENG-48
• OSTI ID: 6889189
• Report Number(s): GA-A-21053; CONF-920913--21; ON: DE93002674
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700310* -- Plasma Confinement-- (1992-)
CLOSED PLASMA DEVICES
CONFINEMENT
CONFINEMENT TIME
CURRENT DENSITY
DOUBLET-3 DEVICE
EDGE LOCALIZED MODES
H-MODE PLASMA CONFINEMENT
INSTABILITY
MODIFICATIONS
PLASMA CONFINEMENT
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
STABILITY
THERMONUCLEAR DEVICES
TOKAMAK DEVICES