Journal article
Scrape-off layer transport and filament characteristics in high-density tokamak regimes
Consorzio RFX1
United Kingdom Atomic Energy Authority2
University of Innsbruck3
University of Seville4
VTT Technical Research Centre of Finland Ltd.5
Aristotle University of Thessaloniki6
Josef Stefan Institute7
Technical University of Denmark8
Dutch Institute for Fundamental Energy Research9
TCV Team10
EUROfusion MST1 Team11
Laboratorio Nacional de Fusíon12
University of California at San Diego13
Plasma Physics and Fusion Energy, Department of Physics, Technical University of Denmark14
Department of Physics, Technical University of Denmark15
University of York16
Swiss Federal Institute of Technology Lausanne17
Max Planck Institute for Plasma Physics18
Instituto Superior Técnico19
...and 9 moreA detailed cross-device investigation on the role of filamentary dynamics in high-density regimes has been performed within the EUROfusion framework, comparing the ASDEX Upgrade (AUG) and TCV tokamaks. Both devices run density ramp experiments at different levels of plasma current, keeping the toroidal field or q 95 constant in order to disentangle the role of the parallel connection length and the current.
During the scan at a constant toroidal field, in both devices the scrape-off layer (SOL) profiles tend to develop a clear SOL density shoulder at a lower edge density whenever the current is reduced. Different current behaviour is substantially reconciled in terms of the edge density normalized to the Greenwald fraction.
During the scan at constant q 95 AUG exhibits similar behaviour, whereas in TCV no upstream profile modification signature has been observed at lower current levels. The latter behaviour has been ascribed to the lack of target density rollover. The relation between the upstream density profile modification and detachment condition has been investigated.
For both devices the relation between blob size and the SOL density e-folding length is found independent of the plasma current, with the observation of a clear increase in blob size and the edge density normalized to a Greenwald fraction. ASDEX Upgrade has also explored filamentary behaviour in the H-mode.
The experiments in AUG have focused on the role of neutrals, performing discharges with and without cryogenic pumps, highlighting how high neutral pressure, not only in the divertor but also at the midplane, is needed in order to develop an H-mode SOL profile shoulder in AUG.
Language: | English |
---|---|
Year: | 2019 |
Pages: | 016001 |
ISSN: | 17414326 , 00295515 and 10185577 |
Types: | Journal article |
DOI: | 10.1088/1741-4326/ab423e |
ORCIDs: | 0000-0003-4401-5346 , 0000-0002-7824-3307 , 0000-0002-7346-8312 , 0000-0002-3823-1002 , 0000-0003-1040-8918 , 0000-0002-0751-8182 , 0000-0003-3926-1374 , 0000-0003-2230-4112 , 0000-0002-9290-7413 , 0000-0002-7415-1894 , 0000-0003-0107-5787 , 0000-0003-4875-6213 , 0000-0001-5968-3684 , 0000-0001-9896-6732 , 0000-0002-5162-509X , 0000-0002-8034-4756 , Nielsen, A.H. , 0000-0002-4156-6671 , Rasmussen, J.J. , 0000-0001-7347-5515 , 0000-0002-9726-1519 , 0000-0002-6403-0511 , 0000-0002-2350-2033 , 0000-0002-0661-5909 and Naulin, V. |