A recent study published in Nuclear Materials and Energy by Florian Effenberg et al. examines the impact of three-dimensional geometry on heat fluxes within island divertor configurations of the Wendelstein 7-X (W7-X) stellarator. The research investigates how different configurations affect the heat loads in the standard and high mirror magnetic configurations at W7-X.

The paper presents findings from the inaugural operation of the island divertor. The results indicate a significant effect of the stellarator's three-dimensional island geometry on the distribution of heat fluxes. The study showcases the implementation of a high mirror configuration that achieves a more even distribution of heat load across the divertor's primary targets, representing an advancement in device operation safety and stability.

The study utilized transport calculations with the EMC3-EIRENE code to analyze the dependence of heat flux distributions on the device's configurations and the intricacies of the three-dimensional island geometry. These calculations were validated against infrared camera measurements, which confirmed the predicted global heat load distributions for the standard configuration and revealed a more uniform distribution in the high mirror configurations.

Moreover, the research delves into the local heat load profiles, uncovering positional offsets of up to 5 centimeters and peak heat flux variations, which underscores the challenges in aligning experimental findings with three-dimensional modeling predictions.

Further explorations with the HINT code into the three-dimensional equilibrium of a high-performance (high-beta) scenario equipped with a high mirror configuration were also reported. It was found that, despite an increase in the stochastic behavior of the plasma equilibrium, the island divertor maintains its structural integrity. However, the size of the islands and the parallel transport paths experience notable changes, influencing the divertor heat flux patterns substantially.

These findings enhance the understanding of power exhaust management in stellarator configurations and provide a foundation for future research on island divertor and plasma-material interactions in W7-X high-performance scenarios. 

Florian Effenberg et al., "Investigation of 3D effects on heat fluxes in performance-optimized island divertor configurations at Wendelstein 7-X" Nuclear Materials and Energy, Volume 18, January 2019, Pages 262-267, DOI 10.1016/j.nme.2019.01.006