Lower hybrid experiments at the 1 MW level on Alcator C: heating and current drive

Conference · Sun Apr 01 04:00:00 EST 1984

OSTI ID:7129692

Porkolab, M; Lloyd, B; Schuss, J J; Takase, Y; Texter, S; Watterson, R; Bonoli, P; Englade, R; Fiore, C; Gandy, R

Lower hybrid current drive and heating experiments have been carried out on the Alcator C tokamak at power levels up to 1.15 MW in the density range 1.0 x 10/sup 13/ less than or equal to anti n/sub e/(cm/sup -3/) less than or equal to 1.0 x 10/sup 14/. By launching waves with 67/sup 0/, 90/sup 0/ or 112/sup 0/ phasing of adjacent waveguides, maximum flat-top current drive efficiencies of eta = R(m) x n(10/sup 14/cm/sup -3/)I(MA)/P(MW) = 0.12 at B = 10 tesla, and eta approx. = 0.08 at B = 8 tesla were obtained with molybdenum limiters. With graphite, or silicon-carbide coated graphite limiters the efficiencies were 30 to 40% lower. Current ramping experiments have also been carried out at densities up to anti n approx. = 6 x 10/sup 13/cm/sup -3/. By phasing the adjacent waveguides at 180/sup 0/, heating experiments were performed in the density range 8 x 10/sup 13/ less than or equal to anti n(cm/sup -3/) less than or equal to 2 x 10/sup 14/ in both hydrogen and deuterium plasmas. This range of densities corresponds to the electron Landau heating mode. Using molybdenum limiters, typical heating rates of the order of eta/sub H/ = delta ..sigma.. n/sub j/T/sub j//P/sub rf/ approx. = 10 eV/kW 10/sup 13/cm/sup -3/ were obtained, whereas with the SiC coated graphite limiters heating rates up to eta/sub H/ approx. = 22 were achieved. Measurements of soft and hard x-rays indicate the presence of substantial electron tails in both the current drive and the electron heating regimes. A combined transport, ray-tracing and Fokker-Planck code is used to analyze and model both the heating and the current drive results.

• Research Organization: Massachusetts Inst. of Tech., Cambridge (USA). Plasma Fusion Center
• DOE Contract Number: AC02-78ET51013
• OSTI ID: 7129692
• Report Number(s): DOE/ET/51013-121; PFC/CP-84-7; CONF-840311-11; ON: DE84010586
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700101* -- Fusion Energy-- Plasma Research-- Confinement
Heating
& Production
ALCATOR DEVICE
CARBIDES
CARBON
CARBON COMPOUNDS
CLOSED PLASMA DEVICES
CURRENT-DRIVE HEATING
ELECTRIC HEATING
ELECTROMAGNETIC RADIATION
ELECTRONIC EQUIPMENT
ELEMENTAL MINERALS
ELEMENTS
EQUIPMENT
GRAPHITE
HEATING
HIGH-FREQUENCY HEATING
IONIZING RADIATIONS
JOULE HEATING
LIMITERS
LOWER HYBRID HEATING
METALS
MICROWAVE EQUIPMENT
MINERALS
MOLYBDENUM
NONMETALS
PLASMA DENSITY
PLASMA HEATING
RADIATIONS
RESISTANCE HEATING
SILICON CARBIDES
SILICON COMPOUNDS
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
TRANSITION ELEMENTS
X RADIATION