Confinement physics of H-mode discharges in DIII-D

• Published in: Plasma physics and controlled fusion Vol. 31; no. 10; pp. 1649 - 1664
• Main Authors: Burrell, K H, Allen, S L, Bramson, G, Brooks, N H, Callis, R W, Carlstrom, T N, Chu, M S, Colleraine, A P, Content, D, DeBoo, J C, Dominguez, R R, Ferron, J R, Freeman, R L, Gohil, P, Greenfield, C M, Groebner, R J, Haas, G, Heidbrink, W W, Hill, D N, Hinton, F L, Hong, R -M, Howl, W, Hsieh, C L, Jackson, G L, Jahns, G L, James, R A, Kellman, A G, Kim, J, Lao, L L, Lazarus, E A, Lehecka, T, Lister, J, Lohr, J, Luce, T C, Luxon, J L, Mahdavi, M A, Matsumoto, H, Mayberry, M, Moeller, C P, Neyatani, Y, Ohkawa, T, Ohyabu, N, Okazaki, T, Osborne, T H, Overskei, D O, Ozeki, T, Peebles, A, Perkins, S, Perry, M, Petersen, P I, Petrie, T W, Philipona, R, Phillips, J C, Pinsker, R, Politzer, P A, Porter, G D, Prater, R, Rensink, M E, Schaffer, M J, Schissel, D P, Scoville, J T, Seraydarian, R P, Shimada, M, Simonen, T C, Snider, R T, Staebler, G M, Stallard, B W, Stambaugh, R D, Stav, R D, John, H St, Stockdale, R E, Strait, E J, L, Taylor P, Taylor, T S, Trost, P K, Stroth, U, Waltz, R E, Wolfe, S M, Wood, R D, Wroblewski, D
• Format: Journal Article Conference Proceeding
• Language: English
• Published: United States IOP Publishing 01.08.1989
• Subjects: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 700101 - Fusion Energy- Plasma Research- Confinement, Heating, & Production; BEAM INJECTION; CLOSED PLASMA DEVICES; CONFINEMENT; CONFINEMENT TIME; DEUTERIUM; DOUBLET-3 DEVICE; ELECTRIC FIELDS; ELECTRON TEMPERATURE; FLUCTUATIONS; HEAT FLUX; HEATING; HYDROGEN ISOTOPES; ION TEMPERATURE; ISOTOPES; LIGHT NUCLEI; NEUTRAL ATOM BEAM INJECTION; NUCLEI; ODD-ODD NUCLEI; PLASMA CONFINEMENT; PLASMA HEATING; STABLE ISOTOPES; THERMONUCLEAR DEVICES; TOKAMAK DEVICES; VARIATIONS
• ISSN: 0741-3335; 1361-6587
• DOI: 10.1088/0741-3335/31/10/012

Our data indicate that the L-mode to H-mode transition in the DIII-D tokamak is associated with the sudden reduction in anomalous, fluctuation-connected transport across the outer midplane of the plasma. In addition to the reduction in edge density and magnetic fluctuations observed at the transition, the edge radial electric field becomes more negative after the transition. We have determined the scaling of the H-mode power threshold with various plasma parameters; the roughly linear increase with plasma density and toroidal field are particularly significant. Control of the ELM frequency and duration by adjusting neutral beam input power has allowed us to produce H-mode plasmas with constant impurity levels and durations up to 5 s. Energy confinement time in Ohmic H-mode plasmas and in deuterium H-mode plasmas with deuterium beam injection can exceed saturated Ohmic confinement times by at least a factor of two. Energy confinement times above 0.3 s have been achieved in these beam-heated plasmas with plasma currents in the range of 2.0 to 2.5 MA. Local transport studies have shown that electron and ion thermal diffusivities and angular momentum diffusivity are comparable in magnitude and all decrease with increasing plasma current. 51 refs., 16 figs.