Investigation of lower hybrid wave coupling and current drive experiments at different configurations in experimental advanced superconducting tokamak

Journal Article · Mon Aug 15 00:00:00 EDT 2011 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.3624778· OSTI ID:22043404

Ding, B J; Qin, Y L; Li, W K; Li, M H; Kong, E H; Zhang, L; Wang, M; Xu, H D; Hu, H C; Xu, G S; Shan, J F; Liu, F K; Zhao, Y P; Wan, B N; Li, J G; Group, EAST ^[1]; Ekedahl, A; Peysson, Y; Decker, J ^[2]

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1. Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)
2. CEA, IRFM, F-13108 Saint Paul-Lez-Durance (France)

Using a 2 MW 2.45 GHz lower hybrid wave (LHW) system installed in experimental advanced superconducting tokamak, we have systematically carried out LHW-plasma coupling and lower hybrid current drive experiments in both divertor (double null and lower single null) and limiter plasma configuration with plasma current (I{sub p}) {approx} 250 kA and central line averaged density (n{sub e}) {approx} 1.0-1.3 x 10{sup 19} m{sup -3} recently. Results show that the reflection coefficient (RC) first is flat up to some distance between plasma and LHW grill, and then increases with the distance. Studies indicate that with the same plasma parameters, the best coupling is obtained in the limiter case (with plasma leaning on the inner wall), followed by the lower single null, and the one with the worst coupling is the double null configuration, explained by different magnetic connection length. The RCs in the different poloidal rows show that they have different coupling characteristics, possibly due to local magnetic connection length. Current drive efficiency has been investigated by a least squares fit with N{sub //}{sup peak}=2.1, where N{sub //}{sup peak} is the peak value of parallel refractive index of the launched wave. Results show that there is no obvious difference in the current drive efficiency between double null and lower single null cases, whereas the efficiency is somewhat small in the limiter configuration. This is in agreement with the ray tracing/Fokker-Planck code simulation by LUKE/C3PO and can be interpreted by the power spectrum up-shift factor in different plasma configurations. A transformer recharge is realized with {approx}0.8 MW LHW power and the energy conversion efficiency from LHW to poloidal field energy is about 2%.

• OSTI ID: 22043404
• Journal Information: Physics of Plasmas, Vol. 18, Issue 8; Other Information: (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
APPROXIMATIONS
CONFINEMENT
DENSITY
DIVERTORS
EFFICIENCY
ENERGY CONVERSION
FOKKER-PLANCK EQUATION
HT-7U TOKAMAK
LEAST SQUARE FIT
LIMITERS
LOWER HYBRID CURRENT DRIVE
LOWER HYBRID HEATING
PEAKS
PLASMA
PLASMA SIMULATION
REFLECTION
REFRACTIVE INDEX
SPECTRA
SUPERCONDUCTING DEVICES
THERMONUCLEAR REACTORS