The ultra-fast swept reflectometer with the sweep time of 1 μs, inferior to the characteristic turbulent time scale, has provided the measurements of the fast density and density fluctuation evolution across major parts of tokamak plasma radius. The L-H transitions in a series of plasma discharges in ASDEX Upgrade have been studied with a high temporal resolution. The comparison of the density fluctuation behaviour in L- and H-mode is presented. The I-phase oscillation dynamics has been described in terms of the density fluctuation level, the radial electric field and the normalised electron pressure gradient. Indications for a phase shift between the turbulence and the radial electric field are observed in the beginning of the I-phase, where the turbulence grows first and the radial electric field increase follows. In the established I-phase the electric field and the turbulence are in phase.

Medvedeva, A., Bottereau, C., Clairet, F., Hennequin, P., Stroth, U., Birkenmeier, G., et al. (2017). Density profile and turbulence evolution during L-H transition studied with the ultra-fast swept reflectometer on ASDEX Upgrade. PLASMA PHYSICS AND CONTROLLED FUSION, 59(12) [10.1088/1361-6587/aa9251].

Density profile and turbulence evolution during L-H transition studied with the ultra-fast swept reflectometer on ASDEX Upgrade

Cavedon M.;
2017

Abstract

The ultra-fast swept reflectometer with the sweep time of 1 μs, inferior to the characteristic turbulent time scale, has provided the measurements of the fast density and density fluctuation evolution across major parts of tokamak plasma radius. The L-H transitions in a series of plasma discharges in ASDEX Upgrade have been studied with a high temporal resolution. The comparison of the density fluctuation behaviour in L- and H-mode is presented. The I-phase oscillation dynamics has been described in terms of the density fluctuation level, the radial electric field and the normalised electron pressure gradient. Indications for a phase shift between the turbulence and the radial electric field are observed in the beginning of the I-phase, where the turbulence grows first and the radial electric field increase follows. In the established I-phase the electric field and the turbulence are in phase.
Articolo in rivista - Articolo scientifico
I-phase; L-H transition; nuclear fusion; plasma physics; reflectometry; tokamak; turbulence;
English
Medvedeva, A., Bottereau, C., Clairet, F., Hennequin, P., Stroth, U., Birkenmeier, G., et al. (2017). Density profile and turbulence evolution during L-H transition studied with the ultra-fast swept reflectometer on ASDEX Upgrade. PLASMA PHYSICS AND CONTROLLED FUSION, 59(12) [10.1088/1361-6587/aa9251].
Medvedeva, A; Bottereau, C; Clairet, F; Hennequin, P; Stroth, U; Birkenmeier, G; Cavedon, M; Conway, G; Happel, T; Heuraux, S; Molina, D; Silva, A; Willensdorfer, M
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/354915
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