Journal article
Metal impurity transport control in JET H-mode plasmas with central ion cyclotron radiofrequency power injection
Consorzio RFX1
Risø National Laboratory for Sustainable Energy, Technical University of Denmark2
VTT Technical Research Centre of Finland Ltd.3
Max Planck Institute4
Queen's University Belfast5
United Kingdom Atomic Energy Authority6
Euratom Association-IST7
EURATOM Association8
Association EURATOM-Belgian State9
EURATOM-ENEA sulla Fusione10
Plasma Physics and Technology Programme, Risø National Laboratory for Sustainable Energy, Technical University of Denmark11
...and 1 moreThe scan of ion cyclotron resonant heating (ICRH) power has been used to systematically study the pump out effect of central electron heating on impurities such as Ni and Mo in H-mode low collisionality discharges in JET. The transport parameters of Ni and Mo have been measured by introducing a transient perturbation on their densities via the laser blow off technique.
Without ICRH Ni and Mo density profiles are typically peaked. The application of ICRH induces on Ni and Mo in the plasma centre (at normalized poloidal flux ρ = 0.2) an outward drift approximately proportional to the amount of injected power. Above a threshold of ICRH power of about 3 MW in the specific case the radial flow of Ni and Mo changes from inwards to outwards and the impurity profiles, extrapolated to stationary conditions, become hollow.
At mid-radius the impurity profiles become flat or only slightly hollow. In the plasma centre the variation of the convection-to-diffusivity ratio v/D of Ni is particularly well correlated with the change in the ion temperature gradient in qualitative agreement with the neoclassical theory. However, the experimental radial velocity is larger than the neoclassical one by up to one order of magnitude.
Gyrokinetic simulations of the radial impurity fluxes induced by electrostatic turbulence do not foresee a flow reversal in the analysed discharges.
Language: | English |
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Publisher: | IOP Publishing |
Year: | 2011 |
Pages: | 033002 (11pp) |
ISSN: | 10185577 , 00295515 and 17414326 |
Types: | Journal article |
DOI: | 10.1088/0029-5515/51/3/033002 |
ORCIDs: | Naulin, Volker |