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Experimental validation of physics-based plasma boundary models

The working group funded by the BMFTR focuses on the experimental validation of physics-based plasma boundary models and the further development of plasma diagnostics.

Motivation:

The plasma edge region in fusion reactors with magnetic confinement has a decisive influence on reactor performance and the stress on wall materials. Instabilities caused by strong pressure gradients, such as plasma edge modes and filaments, can lead to temporarily increased wall stresses, which endanger material integrity and release contaminants. Validated, physics-based plasma edge models are essential for predicting and optimizing the performance and wall stresses of future fusion reactors.

Research approach:

The aim of the project is to develop a validation environment for plasma boundary models that combines simulations and experimental data using synthetic diagnostics. This allows a quantitative comparison of plasma parameters such as density and temperature, resolved on small spatial and temporal scales, which are crucial for turbulent transport in the plasma boundary region. Key diagnostics here are thermal helium beam diagnostics, Langmuir probes, reflectometers, and hot cathode ionization manometers for neutral gas pressure measurement. The experimental work includes high-resolution measurements on the Stellarator W7-X and the Tokamak ASDEX Upgrade. In addition, an optimized version of the manometer will be developed and validated through laboratory tests within this working group.

Prospects:

Through the close linking of tokamak and stellarator research, modeling, and experiments, key processes are identified that are crucial for the development of high-performance, ELM-free operating regimes and the associated loads on the reactor wall. This supports the ongoing development of plasma edge codes. Additionally, the optimized pressure gauges are crucial for the real-time control of fusion reactors.