H-mode study in DIII-D

Conference · Tue Mar 01 04:00:00 EST 1988

OSTI ID:6986273

Ohyabu, N; Allen, S; Brooks, N H; Bramson, G; Burrell, K H; Callis, R W; Carlstrom, T N; Colleraine, A P; Content, D; DeBoo, J C; Gohil, P; Groebner, R J; Howl, W; Hill, D N; Hong, R M

H-mode has been observed in DIII-D single null divertor discharges. Many observed features are similar to those of other devices. In this paper, we discuss new and detailed experimental findings mostly from DIII-D beam heated discharges. The H-mode transition requires a minimum input power and a minimum density. These minimum values depend on various plasma parameters. The detailed parametric dependence has not yet been established. However, H-mode accessibility is easiest for low B/sub T/, D-plasma with ion /gradient/B drift toward X-point. Under such conditions, the H-transition is achieved with low power (0.8 MW) ECH alone. Furthermore, a temporary H-mode phase, lasting /approximately/30 msec is triggered by a sawtooth crash in purely ohmically-heated, low q discharges. After the transition, the density profile becomes flat with a very steep edge gradient within several msec and further develops into a hollow profile. The average density continuously increases during entire H-phase until an Edge Localized Mode (ELM) occurs. On the other hand, the edge electron temperature rises rapidly from 200 eV to 350 eV within /approximately/50 msec after the transition and then saturates. 9 refs., 4 figs.

• Research Organization: General Atomic Co., San Diego, CA (USA)
• DOE Contract Number: AC03-84ER51044
• OSTI ID: 6986273
• Report Number(s): GA-A-19204; CONF-880534-8; ON: DE88011664
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700101 -- Fusion Energy-- Plasma Research-- Confinement
Heating
& Production
700103* -- Fusion Energy-- Plasma Research-- Kinetics
BALLOONING INSTABILITY
CONFINEMENT
DIVERTORS
DOUBLET REACTORS
ELECTRON DENSITY
ELECTRON TEMPERATURE
FLUCTUATIONS
HEATING
INSTABILITY
MAGNETIC FIELDS
PLASMA CONFINEMENT
PLASMA HEATING
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
PRESSURE GRADIENTS
THERMONUCLEAR REACTORS
TOKAMAK TYPE REACTORS
VARIATIONS