Energy confinement in auxiliary-heated divertor and limiter discharges in the DIII-D Tokamak

Conference · Sat Oct 01 00:00:00 EDT 1988

OSTI ID:6736873

Burrell, K H; Allen, S L; Bramson, G; Brooks, N H; Callis, R W; Carlstrom, T N; Chance, M S; Chu, M S; Colleraine, A P; Content, D; DeBoo, J C; Dominguez, R R; Ejima, S; Ferron, J R; Freeman, R L; Fukumoto, H; Gohil, P; Gottardi, N; Greenfield, C M; Groebner, R J ; Haas, G; Harvey, R W; Heidbrink, W W; Helton, F J; Hill, D N; Hinton, F L; Hong, R M; Hosogane, N; Howl, W; Hsieh, C L; Jackson, G L; Jahns, G L; James, R A; Kellman, A G; Kim, J; Kinoshita, S; Lao, L L; Lazarus, E A; LeHecka, T; Lee, P; Lister, J; Lohr, J; Lomas, P; Luce, T C; Luxon, J L; Mahdavi, M A; Matsuda, K; Matsumoto, H; Mayberry, M; Moeller, C P; Neyatani, Y; Ohkawa, T; Ohyabu, N; Osborne, T H; Overskei, D O; Ozeki, T; Peebles, A; Perkins, S; Perry, M; Petersen, P I; Petrie, T W; Philipono, R; Phillips, J C; Pinsker, R; Politzer, P A; Porter, G D; Prater, R; Remsen, D B; Rensink, M E; Sakamoto, K; Schafer, M J; Schissel, D P; Scoville, J T; Sera,

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. The data indicate that the H-mode transition is associated with the sudden reduction in anomalous, fluctuation-connected transport across the outer midplane of the plasma. We find that the edge localized modes (ELMs) are triggered when the pressure gradient at the edge of the plasma exceeds the threshold given by ideal ballooning theory. Energy confinement time increases linearly with plasma current until the safety factor at the 95% flux surface q/sup 95/ drops below three; at q/sub 95/ < 3, it is independent of current and, at constant q/sub 95/, depends linearly on toroidal field. Controlling the effects of ELMs has allowed us to produce nearly-steady-state plasmas with H-mode durations up to 4.4 seconds. Energy confinement time in H-mode plasmas created with Ohmic heating alone shows a factor of two improvements over standard Ohmic plasmas. Confinement time in 2.0 MA H-mode plasmas with neutral beam heating can significantly exceed the standard Ohmic value also. Local transport studies have shown that the thermal diffusivity in the outer half of the plasma in neutral-beam-heated H-mode is a factor of three lower than the L-mode diffusivity at the same plasma density. 32 refs., 8 figs.

• Research Organization: General Atomics Co., San Diego, CA (USA); Lawrence Livermore National Lab., CA (USA); Johns Hopkins Univ., Baltimore, MD (USA); Shinetsu Chemical Industry Co. Ltd., Takefu, Fuki (Japan); Hitachi Ltd., Tokyo (Japan); JET Joint Undertaking, Abingdon (UK); Max-Planck-Institut fuer Plasmaphysik, Garching (Germany, F.R.); California Univ., Irvine (USA); Japan Atomic Energy Research Inst., Tokyo; Centre de Recherches en Physique des Plasmas, Lausanne (Switzerland); Nagoya Univ. (Japan). Inst. of Plasma Physics; University of Southern California, Los Angeles (USA)
• DOE Contract Number: AC03-84ER51044
• OSTI ID: 6736873
• Report Number(s): GA-A-19443; CONF-881015-22; ON: DE89001438; TRN: 88-035879
• Resource Relation: Conference: 12. international conference on plasma physics and controlled nuclear fusion research, Nice, France, 12 Oct 1988; Other Information: Portions of this document are illegible in microfiche products
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
DOUBLET-3 DEVICE
PLASMA CONFINEMENT
CONFINEMENT TIME
DIVERTORS
JOULE HEATING
LIMITERS
PLASMA DENSITY
TRANSPORT THEORY
CLOSED PLASMA DEVICES
CONFINEMENT
ELECTRIC HEATING
HEATING
PLASMA HEATING
RESISTANCE HEATING
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
700101* - Fusion Energy- Plasma Research- Confinement
Heating
&amp; Production