Direct electron heating by 60 MHz fast waves on DIII-D

Conference · Tue Oct 01 00:00:00 EDT 1991

OSTI ID:5003744

Petty, C C; Pinsker, R I; Mayberry, M J; Chiu, S C; Luce, T C; Prater, R ^[1]; Porkolab, M; Bonoli, P T ^[2]; de Haas, J C.M.; James, R A ^[3]; Baity, F W; Goulding, R H; Hoffman, D J ^[4]

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1. General Atomics, San Diego, CA (United States)
2. Massachusetts Inst. of Tech., Cambridge, MA (United States). Plasma Fusion Center
3. Lawrence Livermore National Lab., CA (United States)
4. Oak Ridge National Lab., TN (United St

Efficient direct electron heating by fast waves has been observed on the DIII-D tokamak. A four strap antenna with (0,{pi},0,{pi}) phasing launched up to 1.6 MW of fast wave power with {vert bar}n{sub {parallel}}{vert bar} {approx} 11. This {vert bar}n{sub {parallel}}{vert bar} is suitable for strong electron interaction in ohmic target plasmas (T{sub e} {le} 2 keV). Ion cyclotron absorption was minimized by keeping the hydrogen fraction low ({lt}3%) in deuterium discharges and by operating at high ion cyclotron harmonics ({omega} = 4{Omega}{sub H} = 8{Omega}{sub D} at 1T). The fast wave electron heating was weak for central electron temperatures below 1 keV, but improved substantially with increasing T{sub e}. Although linear theory predicts a strong inverse magnetic field scaling of the first pass absorption, the measured fast-wave heating efficiency was independent of magnetic field. Multiple pass absorption of the fast waves appears to be occurring since at 2.1 T nearly 100% efficient plasma heating is observed while the calculated first pass absorption is 6% to 8%. The central electron temperature during fast wave heating also increased with magnetic field. The improved electron heating at higher magnetic fields may be due in part to a peaking of the ohmic plasma current and the ohmic electron temperature profiles. Centrally peaked deposition profiles were measured by modulating the fast wave power at 10 Hz and observing the local electron temperature response across the plasma. 11 refs., 10 figs.

• Research Organization: General Atomics, San Diego, CA (United States)
• Sponsoring Organization: USDOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC03-89ER51114; AC02-78ET51013; AC05-84OR21400
• OSTI ID: 5003744
• Report Number(s): GA-A-20688; CONF-910869-22; ON: DE92002859
• Resource Relation: Conference: 9. topical conference on radio frequency power in plasmas, Charleston, SC (United States), 19-21 Aug 1991
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
DOUBLET-3 DEVICE
CURRENT-DRIVE HEATING
NON-INDUCTIVE CURRENT DRIVE
ABSORPTION
ANTENNAS
EFFICIENCY
ELECTRON TEMPERATURE
ICR HEATING
LANDAU DAMPING
MAGNETIC FIELDS
CLOSED PLASMA DEVICES
DAMPING
ELECTRIC HEATING
ELECTRICAL EQUIPMENT
EQUIPMENT
HEATING
HIGH-FREQUENCY HEATING
JOULE HEATING
PLASMA HEATING
RESISTANCE HEATING
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
700101* - Fusion Energy- Plasma Research- Confinement
Heating
& Production