Doppler backscattering system for measuring fluctuations and their perpendicular velocity on Tore Supra

Hennequin, Pascale; Honoré, Cyrille; Truc, A.; Quéméneur, A.; Lemoine, N.; Chareau, J. M.; Sabot, R.

doi:10.1063/1.1787920

Cited by 95 publications

(76 citation statements)

References 16 publications

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“…The employed diagnostic technique is Doppler reflectometry, which is relatively new (∼ 10 years), but used on several tokamaks and stellarators worldwide [38][39][40][41][42][43][44].…”

Section: Introductionmentioning

confidence: 99%

Scale-selective turbulence reduction in H-mode plasmas in the TJ-II stellarator

Happel

Estrada²,

Blanco³

et al. 2011

Physics of Plasmas

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Wavenumber spectra of density turbulence in L-and H-mode plasmas have been measured in the TJ-II stellarator by means of Doppler reflectometry. A pronounced suppression of the density fluctuation level is observed in H-mode close to the radial position of maximum radial electric field (Er) shear. Furthermore, intermediate scale density turbulence is reduced preferentially. This effect can be interpreted within the framework of vortex stretching feeding energy through Reynolds stress into zonal flows, while shear decorrelation of turbulent structures might not play a central role in TJ-II. Moreover, it is shown that in both L-and H-mode, the phase velocity of density fluctuations does not depend on the structure scale.

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“…The employed diagnostic technique is Doppler reflectometry, which is relatively new (∼ 10 years), but used on several tokamaks and stellarators worldwide [38][39][40][41][42][43][44].…”

Section: Introductionmentioning

confidence: 99%

Scale-selective turbulence reduction in H-mode plasmas in the TJ-II stellarator

Happel

Estrada²,

Blanco³

et al. 2011

Physics of Plasmas

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“…This technique allows the measurement of the density turbulence and its perpendicular rotation velocity, at different turbulence scales and with good spatial and temporal resolution [37][38][39][40]. The perpendicular rotation velocity of the plasma turbulence has been shown to be dominated by the E × B velocity, which allows the determination of the radial electric field, E r .…”

Section: Doppler Reflectometry Systemsmentioning

confidence: 99%

Microwave Reflectometry Diagnostics: Present Day Systems and Challenges for Future Devices

Estrada

Nagasaki

Blanco³

et al. 2012

Plasma and Fusion Research

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Microwave reflectometry technique has experienced significant advances in the last two decades becoming a very attractive diagnostic presently used in almost all fusion devices. This technique allows measuring electron density profiles, plasma instabilities, turbulence and radial electric fields with excellent spatial and temporal resolution. Although it is not straightforward, the extension of reflectometry to future devices is possible partially due to the limited access needed to accommodate the antennas inside the vacuum vessel keeping the sensitive elements as microwave sources and detectors outside the radiation area. However, in order to achieve a good diagnostic performance, limitations related to relativistic effects, intense neutron-and γ-radiation and long pulse operation have to be considered in the reflectometer design phase.

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“…Spectra shown in Fig 1 b exhibit different behaviours, according to their radial position : slopes for low k r are almost identical, S δn (k r , r) ∼ k −2 r , for 1 cm −1 < k r < 10 cm −1 ( 0.1 < k r ρ s < 1, ρ s being the electronic Larmor gyroradius ). Some discrepancies appear while comparing with k θ spectra previously extracted from the coherent forward Thomson scattering diagnostic [7], scaling with k −3.5 ⊥ for 6 cm −1 < k ⊥ 14 cm −1 ( 0.5 < k ⊥ ρ s < 2.5 ) and the Doppler reflectometry [8] , scaling with…”

Section: Density Fluctuations Spectra and Profiles -Scaling Of δN E /N Ementioning

confidence: 99%

Density Fluctuations Measurements on Tore Supra Tokamak Plasma: Radial Profiles and Spectra

Gerbaud

Heuraux

Clairet

2007

3rd France-Russia Seminar

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Up to now, turbulent processes in fusion plasmas are not clearly identified, then innovative and comprehensible diagnostic measurements are required. Fast-sweep heterodyne reflectometry is always suitable for precise measurement of density profiles but can also be used to reconstruct fluctuation density profiles. A closed-loop upgrade of the method developed in [1] , based on comparisons between simulated and experimental reflected signals, allows us to extract from shot to shot on Tore Supra tokamak the density fluctuations radial wavenumber spectra S(k r ) from the fluctuating phase signal of the X-mode fast-sweep V and W band reflectometers.In this paper we focus on the application of this experimental method of extracting the spatial evolution of the wavenumber spectra and radial density fluctuation profiles of the Tore Supra tokamak plasma. Then we exhibit a density fluctuations scaling with the electronic density gradient length L ne .

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Doppler backscattering system for measuring fluctuations and their perpendicular velocity on Tore Supra

Cited by 95 publications

References 16 publications

Scale-selective turbulence reduction in H-mode plasmas in the TJ-II stellarator

Scale-selective turbulence reduction in H-mode plasmas in the TJ-II stellarator

Microwave Reflectometry Diagnostics: Present Day Systems and Challenges for Future Devices

Density Fluctuations Measurements on Tore Supra Tokamak Plasma: Radial Profiles and Spectra

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