The relation between the macroscopic input power required at ASDEX Upgrade to access the H-mode pthr and the microscopic E × B shear has been investigated via fast charge-exchange recombination spectroscopy (CXRS) measurements at various toroidal magnetic fields, different electron densities, and in both hydrogen and deuterium plasmas. For the H-mode onset, a threshold in the νE×B minimum, an approximation of the E × B shear, has been found. This identifies νE×B and not Er as the important player for the L-H transition. A database of measurements including CXRS, Doppler reflectometry measurements and comparison to neoclassical approximations shows a threshold νE×B of (6.7 ± 1.0) km/s ranging over a factor of three in Pthr. Using these findings, a simple derivation of the Pthr scaling is proposed giving a physics interpretation of the Bt, density and surface dependence of Pthr

Cavedon, M., Birkenmeier, G., Putterich, T., Ryter, F., Viezzer, E., Wolfrum, E., et al. (2020). Connecting the global H-mode power threshold to the local radial electric field at ASDEX Upgrade. NUCLEAR FUSION, 60(6) [10.1088/1741-4326/ab8777].

Connecting the global H-mode power threshold to the local radial electric field at ASDEX Upgrade

Cavedon M.;
2020

Abstract

The relation between the macroscopic input power required at ASDEX Upgrade to access the H-mode pthr and the microscopic E × B shear has been investigated via fast charge-exchange recombination spectroscopy (CXRS) measurements at various toroidal magnetic fields, different electron densities, and in both hydrogen and deuterium plasmas. For the H-mode onset, a threshold in the νE×B minimum, an approximation of the E × B shear, has been found. This identifies νE×B and not Er as the important player for the L-H transition. A database of measurements including CXRS, Doppler reflectometry measurements and comparison to neoclassical approximations shows a threshold νE×B of (6.7 ± 1.0) km/s ranging over a factor of three in Pthr. Using these findings, a simple derivation of the Pthr scaling is proposed giving a physics interpretation of the Bt, density and surface dependence of Pthr
Articolo in rivista - Articolo scientifico
L-H transition; power threshold; radial electric field; tokamak;
English
Cavedon, M., Birkenmeier, G., Putterich, T., Ryter, F., Viezzer, E., Wolfrum, E., et al. (2020). Connecting the global H-mode power threshold to the local radial electric field at ASDEX Upgrade. NUCLEAR FUSION, 60(6) [10.1088/1741-4326/ab8777].
Cavedon, M; Birkenmeier, G; Putterich, T; Ryter, F; Viezzer, E; Wolfrum, E; Dux, R; Happel, T; Hennequin, P; Plank, U; Stroth, U; Willensdorfer, M
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/354897
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