Impact of magnetic configuration and target chamber geometry on target heat flux in ARC-class divertor legs

The compact geometry and high-power operation of the ARC pilot plant design pose a significant and unresolved challenge for divertor heat flux mitigation. In this work, a suite of model-based tools and workflows has been developed to rapidly scope magnetic and geometric effects on divertor performance in ARC-relevant conditions, building on the "Box" framework for isolated SOLPS-ITER domains of single divertor legs pioneered for MAST-U [1]. Recent expansions of these tools allow for realistic baffle and vessel geometries, flexible pumping and puffing locations, and improved characterization of impurities. These capabilities lay the foundation for scoping studies aiming to inform divertor design, contribute to the development of models for plasma control, and optimize helium exhaust in ARC-class devices. Using these new tools, and by adapting the original "Box" model to accommodate the high magnetic field, high density, and power fluxes expected in ARC, the impact of variations in magnetic configuration and target chamber geometry on target parameters are shown. These models enable systematic comparisons at fixed upstream conditions within realistic operating spaces as predicted by the extended Lengyel model [2], facilitating meaningful detachment studies and validation against 0D and high-fidelity, full-domain SOLPS-ITER models.

[1] Cowley et al., NF 2022

[2] Body et al., NF 2025