Greifswald 2024 – scientific programme
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P: Fachverband Plasmaphysik
P 7: Magnetic Confinement III
P 7.1: Invited Talk
Tuesday, February 27, 2024, 11:00–11:30, ELP 6: HS 3
Physics of Electrical Currents and Fields in the Scrape-off Layer of Tokamak Plasmas — •D. Brida1, G. D. Conway1, J. Adamek2, J. Cavalier2, H. Bergstroem1, G. Grenfell1, U. Plank1, and the ASDEX Upgrade Team1 — 1Max-Planck-Institut für Plasmaphysik, Garching/Greifswald, Germany — 2Institute of Plasma Physics of the CAS, Prague, Czech Republic
The outermost layer of tokamak plasmas, the so-called Scrape-Off Layer (SOL), exhibits strong electric fields and currents, which affect the plasma transport in the SOL and possibly also the confinement of the overall plasma. Understanding the physics governing SOL electric fields and currents and having accurate models describing them is therefore potentially crucial to operate and design future fusion devices. The validation and improvement of these models requires detailed comparisons to measurements obtained in present-day tokamaks, such as ASDEX Upgrade in Garching.
This contribution provides an introduction to the physics of SOL electric fields and currents and presents recent experimental studies conducted at ASDEX Upgrade and other tokamaks. The dependence of the electric field on the divertor conditions, measured by Langmuir probes, is analyzed for different plasma states. Using an analytical model, based on Ohm's law, it is shown how the divertor conditions are related to the electric field further upstream. The studies highlight the pivotal role of the divertor state in determining the electric field and show how currents can lead to substantial heat fluxes onto the divertor target.
Keywords: Scrape-off layer; Divertor; Currents; Electric Fields; Nuclear Fusion