Near- and far scrape-off layer transport studies in detached, small-ELM ASDEX Upgrade discharges by means of EMC3-EIRENE

We compare various diagnostics characterizing an ASDEX Upgrade upper single-null discharge to EMC3-EIRENE simulations now including volumetric recombination and main chamber plasma-wall interaction but not yet drifts. The discharge is in a small-ELM regime and is approaching detachment due to a dens...

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Bibliographic Details
Published in:Plasma physics and controlled fusion 2020-10, Vol.62 (10), p.105016
Main Authors: Lunt, T, Frerichs, H, Bernert, M, Brida, D, Carralero, D, Cavedon, M, David, P, Drenik, A, Faitsch, M, Feng, Y, Griener, M, Herrmann, A, Kurzan, B, Pan, O, Plank, U, Silvagni, D, Willensdorfer, M, Wischmeier, M, Wolfrum, E
Format: Article
Language:English
Subjects:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ASDEX Upgrade
detachment
EMC3-EIRENE
power exhaust
Tokamak
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Summary:We compare various diagnostics characterizing an ASDEX Upgrade upper single-null discharge to EMC3-EIRENE simulations now including volumetric recombination and main chamber plasma-wall interaction but not yet drifts. The discharge is in a small-ELM regime and is approaching detachment due to a density ramp and nitrogen seeding. Time/ELM averaged upstream density, electron and ion temperature measurements as well as downstream ion saturation current, electron temperature and power flux measurements match the simulation within the error bars before and after reaching detachment, qualifying the code for this regime. Although the Ion Cyclotron Resonance Heating (ICRH) antenna limiters are 35 mm away from the separatrix, i.e. ten times the typical near-SOL power fall-off length λqnear = 3.8 mm, they receive power fluxes of several hundreds of kW exceeding the ones to the outer target in the detached phase and strongly contribute to the particle fueling. This is explained by a substantially larger far-SOL power fall-off length λqfar = 25 mm possibly caused by the small ELMs in the detached phase and the occurrence of a density shoulder.
ISSN:0741-3335
1361-6587
DOI:10.1088/1361-6587/aba9ff