Non-Linear Effects on the LH Wave Coupling in Tore Supra and Impact on the LH Current Drive Efficiency

Frincu, B.; Goniche, M.; Hillairet, J.; Petržı́lka, V.; Bobkov, V.; Noterdaeme, Jean-Marie

doi:10.1063/1.3273780

Cited by 12 publications

(9 citation statements)

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“…L 0.5 ). Studies 19 have shown that LHW-plasma coupling was related to the connection length in front of the LHW antenna. Let us consider the 3 configurations of limiter, single null, and double null.…”

Section: Experiments and Resultsmentioning

confidence: 98%

“…The reason for the different coupling characteristics in the different rows is not understood completely yet. Since magnetic connection is local and LHW-plasma coupling depends on connection length, 19 it is speculated that different sensitivity of coupling on distance may be ascribed to the different magnetic connection length. Unfortunately, no density measurement at different rows is available for the present.…”

Section: Experiments and Resultsmentioning

confidence: 99%

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

Ding

Qin

et al. 2011

Physics of Plasmas

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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 p ) $ 250 kA and central line averaged density (n e ) $ 1.0-1.3 Â 10 19 m À3 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 peak == ¼ 2:1, where N 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 $0.8 MW LHW power and the energy conversion efficiency from LHW to poloidal field energy is about 2%.

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Section: Experiments and Resultsmentioning

confidence: 98%

Section: Experiments and Resultsmentioning

confidence: 99%

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

Ding

Qin

et al. 2011

Physics of Plasmas

Self Cite

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“…During October and November 2008, dedicated experiments were carried out in Tore Supra in order to compare the measured power RCs on the C2 and C3 antennas with the numerical results from the ALOHA code. In order to avoid possible non-linear effects [35,36], low power pulses were used, i.e. pulses for which the power density at the mouth of the antenna is lower than 2 MW m −2 (corresponding to a total requested input power of 100 kW for C2 and 75 kW for C3).…”

Section: Comparison With Experimental Resultsmentioning

confidence: 99%

ALOHA: an Advanced LOwer Hybrid Antenna coupling code

et al. 2010

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HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

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“…A complete qualification of this new antenna at a low power (∼200 kW) has been made to test the coupling characteristics (power reflection coefficient, directivity, etc) and to compare them with predicted results from linear coupling theory. Low power experiments are required to avoid non-linear plasma-waves interactions, as previously observed [8]. After briefly mentioning the linear theory of LH coupling in section 2, this paper describes the design and the principle of the new launcher as well as the main differences with a FAM launcher in section 3.…”

Section: Introductionmentioning

confidence: 99%

Coupling characteristics of the ITER-relevant lower hybrid antenna in Tore Supra: experiments and modelling

et al. 2011

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A new concept of lower hybrid antenna for current drive has been proposed for ITER (Bibet et al 1995 Nucl. Fusion 35 1213–23): the passive active multijunction (PAM) antenna that relies on a periodic combination of active and passive waveguides. An actively cooled PAM antenna at 3.7 GHz has recently been installed on the tokamak Tore Supra. This paper summarizes the comprehensive experimental characterization of the coupling properties of the PAM antenna to the Tore Supra plasmas. In this paper, the electromagnetic properties of the antenna are measured at a reduced power (<1 MW) to allow a systematic comparison with linear wave coupling theory and the associated modelling based on the linear ALOHA code. In a wide range of edge electron densities at the antenna aperture (spanning a factor 20 from 0.5 × n c to 10 × n c where n c is the slow wave density cut-off, n c = 1.7 × 1017 m−3 at 3.7 GHz) and antenna phasing, the ALOHA simulations reproduce the experimental results observed on Tore Supra. In addition, reduced power reflection coefficients (<5%) are measured at a low edge density, close to n c, i.e. in the range 0.5–3 × n c. Measurement and analysis with ALOHA of the antenna–plasma scattering matrices provide explanation of the good coupling properties of the PAM antenna close to n c by highlighting the crucial role of the slow wave intercoupling between active and passive waveguides through the plasma edge. This detailed validation of the coupling modelling is an important step towards the validation of the PAM concept in view of further optimizing the electromagnetic properties of the future ITER antenna.

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Non-Linear Effects on the LH Wave Coupling in Tore Supra and Impact on the LH Current Drive Efficiency

Cited by 12 publications

References 0 publications

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

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

ALOHA: an Advanced LOwer Hybrid Antenna coupling code

Coupling characteristics of the ITER-relevant lower hybrid antenna in Tore Supra: experiments and modelling

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