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Experimental study of turbulence on Tore Supra by plasma micro-waves interaction; Etude experimentale de la turbulence sur Tore Supra par interaction plasma micro-ondes

Abstract

Internal small-scale magnetic turbulence is a serious candidate to explain the anomalous heat transport in tokamaks. This turbulence is badly known in the gradient region of large machines. In this work internal magnetic fluctuations are measured on Tore Supra with an original diagnostic : Cross Polarization Scattering (CPS). This experimental tool relies on the Eigenmode change of a probing polarised microwave beam scattered by magnetic fluctuations, close to a cut-off layer for the incident wave. In this work, the diagnostic is first qualified to assess its sensitivity to magnetic fluctuations, and the spatial localisation for its measurements. The magnetic fluctuation behaviour is then analysed over a wide range of plasma current, density and additional power, and interpreted with a simple 1-D scattering model. A scan of the plasma density or magnetic field is used to move the CPS measurement location from r/a = 0.3 to r/a = 0.75. A fluctuation radial profile is obtained by two means. In L-mode discharges, the relation between magnetic fluctuations, temperature profiles and local heat diffusivities is investigated. With all measurements, it is also possible to look for a local parameter correlated to the turbulence in a large domain of plasma conditions. The fluctuation-induced local  More>>
Authors:
Publication Date:
Sep 23, 1996
Product Type:
Thesis/Dissertation
Report Number:
FRCEA-TH-579
Reference Number:
SCA: 700340; PA: AIX-29:041472; EDB-98:085267; SN: 98001990308
Resource Relation:
Other Information: TH: These (D. es Sc.); PBD: 23 Sep 1996
Subject:
70 PLASMA PHYSICS AND FUSION; DEPOLARIZATION; EIGENFUNCTIONS; FLUCTUATIONS; HEAT TRANSFER; MICROWAVE RADIATION; SCATTERING; TORE SUPRA TOKAMAK; TURBULENCE
OSTI ID:
662530
Research Organizations:
Institut National des Sciences et Techniques Nucleaires (INSTN) - CEA Saclay, 91 - Gif-sur-Yvette (France); Paris-7 Univ., 75 (France)
Country of Origin:
France
Language:
French
Other Identifying Numbers:
Other: ON: DE98630289; TRN: FR9702019041472
Availability:
INIS; OSTI as DE98630289
Submitting Site:
FRN
Size:
194 p.
Announcement Date:

Citation Formats

Colas, L. Experimental study of turbulence on Tore Supra by plasma micro-waves interaction; Etude experimentale de la turbulence sur Tore Supra par interaction plasma micro-ondes. France: N. p., 1996. Web.
Colas, L. Experimental study of turbulence on Tore Supra by plasma micro-waves interaction; Etude experimentale de la turbulence sur Tore Supra par interaction plasma micro-ondes. France.
Colas, L. 1996. "Experimental study of turbulence on Tore Supra by plasma micro-waves interaction; Etude experimentale de la turbulence sur Tore Supra par interaction plasma micro-ondes." France.
@misc{etde_662530,
title = {Experimental study of turbulence on Tore Supra by plasma micro-waves interaction; Etude experimentale de la turbulence sur Tore Supra par interaction plasma micro-ondes}
author = {Colas, L}
abstractNote = {Internal small-scale magnetic turbulence is a serious candidate to explain the anomalous heat transport in tokamaks. This turbulence is badly known in the gradient region of large machines. In this work internal magnetic fluctuations are measured on Tore Supra with an original diagnostic : Cross Polarization Scattering (CPS). This experimental tool relies on the Eigenmode change of a probing polarised microwave beam scattered by magnetic fluctuations, close to a cut-off layer for the incident wave. In this work, the diagnostic is first qualified to assess its sensitivity to magnetic fluctuations, and the spatial localisation for its measurements. The magnetic fluctuation behaviour is then analysed over a wide range of plasma current, density and additional power, and interpreted with a simple 1-D scattering model. A scan of the plasma density or magnetic field is used to move the CPS measurement location from r/a = 0.3 to r/a = 0.75. A fluctuation radial profile is obtained by two means. In L-mode discharges, the relation between magnetic fluctuations, temperature profiles and local heat diffusivities is investigated. With all measurements, it is also possible to look for a local parameter correlated to the turbulence in a large domain of plasma conditions. The fluctuation-induced local heat diffusivity expected from the measured fluctuations is estimated using the non-collisional quasi-linear formula: X{sup mag}{sub e} = {pi}qRV{sub te}({delta}B / B){sup 2}. Both the absolute values and the parametric dependence of calculated X{sup mag}{sub e} are close to the electron thermal diffusivities Xe determined by transport analysis. In particular, a threshold is evidenced in the dependence of fluctuation-induced heat fluxes on local {nabla}T{sub e}, which is analogous to the critical gradient for measured heat fluxes. The experimental setup is also sensitive to the Thomson scattering of the probing wave by density fluctuations. Its measurements are analysed as the fluctuations of the amplitude and the phase of an interferometer, thanks to a simple modelling of the plasma poloidal motion. Thus one than measure from the spectra shapes statistical quantities of the plasma movement. (author)}
place = {France}
year = {1996}
month = {Sep}
}