2025 – Extend detachment models to minimal baffling case: XPR stability and leg length dependence

Extend detachment models to minimal baffling case: XPR stability and leg length dependence

2025 Research Campaign, Divertor Science and Innovation

Purpose of Experiment

Regimes with X-point radiators have been obtained in several tokamaks (e.g., ASDEX Upgrade, JET) and are being considered for future devices (ITER, DEMO). A better understanding of access and stability of X-point radiation, including verification of models and validated edge fluid simulations, are critical for extrapolation to future devices. A reduced power/particle balance model has been developed [Stroth NF 2022] to predict access to stable X-point radiation regimes (XPR) and their possible evolution in radiation instabilities (MARFE).

Experimental Approach

This experiment exploits the DIII-D shaping flexibility and unique divertor diagnostics capability (DTS, DivSPRED) to quantitatively test power balance and MHD models for access and stability of X-point radiation with different dominant radiators. Active control of X-point radiation will be tested with radiation controllers to assess potential for stabilization of X-point radiation if unstable MARFE evolution is observed.

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