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Article Dans Une Revue Plasma Physics and Controlled Fusion Année : 2004

Scaling laws of density fluctuations at high-k on Tore Supra

Résumé

Anomalous transport in tokamaks is generally attributed to turbulent fluctuations. Since a large variety of modes are potentially unstable, a wide range of short-scale fluctuations should be measured, with wavenumbers from kρ i ∼ 0.1 to kρ i 1. In the Tore Supra tokamak, a light scattering experiment has made possible fluctuation measurements in the medium-and high-k domains where a transition in the k-spectrum is observed: the fluctuation level decreases much faster than usual observations, typically with a power law S(k) ≡ k −6. A scan of the ion Larmor radius shows that the transition wavenumber scales with ρ i around kρ i ∼ 1.5. This transition indicates that a characteristic length scale should be involved to describe the fluctuation nonlinear dynamics in this range. The resulting very low level of fluctuations at high-k does not support a strong effect of turbulence driven by the electron temperature gradient. For this gyroradius scan, the characteristics of turbulence also exhibit a good matching with predictions from gyro-Bohm scaling: the typical scale length of turbulence scales with the ion Larmor radius, the typical timescales with a/c s ; the turbulence level also scales with ρ i , according to the mixing length rule.
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Dates et versions

hal-03741698 , version 1 (02-08-2022)

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P. Hennequin, R Sabot, C Honoré, G T Hoang, X Garbet, et al.. Scaling laws of density fluctuations at high-k on Tore Supra. Plasma Physics and Controlled Fusion, 2004, 46 (12B), pp.B121 - B133. ⟨10.1088/0741-3335/46/12b/011⟩. ⟨hal-03741698⟩
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