Physics of the electric field in the scrape-off layer in ASDEX Upgrade L-mode discharges and comparison to experiments

0563273 - ÚFP 2023 RIV NL eng J - Journal Article
Brida, D. - Conway, G.D. - Adámek, Jiří - Silvagni, D. - David, P. - Eich, T. - Grenfell, G. - Komm, Michael - Plank, U.
Physics of the electric field in the scrape-off layer in ASDEX Upgrade L-mode discharges and comparison to experiments.
Nuclear Materials and Energy. Roč. 33, October (2022), č. článku 101262. E-ISSN 2352-1791
EU Projects: European Commission(BE) 101052200
Institutional support: RVO:61389021
Keywords : ASDEX Upgrade * Electric field * sol
OECD category: Fluids and plasma physics (including surface physics)
Impact factor: 2.6, year: 2022
Method of publishing: Open access
https://www.sciencedirect.com/science/article/pii/S2352179122001430?via%3Dihub

The electric field in the Scrape-Off Layer (SOL) of fusion plasmas is a key quantity affecting the local plasma transport and possibly also the overall plasma confinement. However, the physics determining the SOL electric field is experimentally not well investigated. In this study a systematic experimental analysis of the electric field in AUG L-mode discharges at various plasma currents, densities and heating powers is presented. In particular, the relation of the electric field to the divertor condition, as measured by Langmuir probes, is analyzed in detail by applying a simplified form of Ohm's law. The analysis shows that the peak value of the radial electric field E-r in the near SOL measured by Doppler reflectometry decreases from about 8 kV/m at the lowest densities to2 kV/m at the highest densities, which is accompanied by a flattening of the outer divertor target electron temperature profiles. The electric field obtained by integrating Ohm's law from the divertor target to the midplane agrees with E-r in the near SOL within the uncertainties, evidencing the quantitative validity of the underlying model. Based on the findings about the relation between the electric field and the target conditions, a scaling to obtain the maximum of E-r in the SOL in terms of upstream parameters is developed.
Permanent Link: https://hdl.handle.net/11104/0340651