Lower hybrid current drive experiments on the MIT Alcator C and Versator II tokamaks

Conference · Thu Aug 01 04:00:00 EDT 1985

OSTI ID:5087173

Knowlton, S; McDermott, S; Porkolab, M; Takase, Y; Texter, S; Bonoli, P; Fiore, C; McCool, S; Mayberry, M; Chen, K I

Energy confinement studies in lower hybrid RF driven discharges at 4.6 GHz have been carried out on the Alcator C tokamak. The electron temperature profile is measured by a five point Thomson scattering system and the ion temperature by charge-exchange analysis. The energy content of the bulk plasma is found to be similar for RF-driven and ohmic discharges of identical current and density. In the parameter range anti n/sub e/ = 3 - 7 x 10/sup 13/ cm/sup -3/, B = 7 - 11 T, I/sub p/ = 100 - 200 kA, q (a) > 8, the RF power needed to sustain the discharge is significantly greater than the ohmic power required to maintain a similar plasma. The gross energy confinement time is lower in the RF-driven discharges than in the ohmic ones by a factor of 1.5 to 4, depending on plasma conditions. The frequency scaling of the density limit for current drive is reported from the Versator II tokamak. The steady-state current drive density limit of anti n/sub e/ = 6 x 10/sup 12/ cm/sup -3/ at 800 MHz. has been raised to a density of at least anti n/sub e/ = 1.0 x 10/sup 13/ cm/sup -3/ at the same toroidal field by operations at a frequency of 2.45 GHz. Superthermal electron effects during RF injection are observed up to a density of anti n/sub e/ = 2.5 x 10/sup 13/ cm/sup -3/.

• Research Organization: Massachusetts Inst. of Tech., Cambridge (USA). Plasma Fusion Center
• DOE Contract Number: AC02-78ET51013
• OSTI ID: 5087173
• Report Number(s): DOE/ET/51013-T157; PFC/CP-85-6; CONF-850927-7; ON: DE86001109
• 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
CHARGE EXCHANGE
CLOSED PLASMA DEVICES
CONFINEMENT
CURRENT-DRIVE HEATING
ELECTRIC HEATING
ELECTRON TEMPERATURE
HEATING
HIGH-FREQUENCY HEATING
INELASTIC SCATTERING
ION TEMPERATURE
JOULE HEATING
LOWER HYBRID HEATING
PLASMA CONFINEMENT
PLASMA HEATING
RESISTANCE HEATING
SCATTERING
THERMONUCLEAR DEVICES
THOMSON SCATTERING
TOKAMAK DEVICES
VERSATOR TOKAMAK