Resilient stellarator divertor characteristics in the Helically Symmetric eXperiment

Garcia, K. A.; Bader, A.; Boeyaert, D.; Boozer, A. H.; Frerichs, H.; Gerard, M. J.; Punjabi, A.; Schmitz, O.

doi:10.1088/1361-6587/adb179

Resilient stellarator divertor characteristics in the Helically Symmetric eXperiment

Journal Article · Wed Feb 12 23:00:00 EST 2025 · Plasma Physics and Controlled Fusion

DOI:https://doi.org/10.1088/1361-6587/adb179· OSTI ID:3010472

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Univ. of Wisconsin, Madison, WI (United States)
Type One Energy Inc., Madison, WI (United States)
Columbia Univ., New York, NY (United States)
Hampton Univ., Hampton, VA (United States)

Resilient divertor features connected to open chaotic edge structures in the Helically Symmetric eXperiment are investigated. For the first time, an expanded vessel wall was considered that would give space for implementation of a physical divertor target structure. The analysis was done for four different magnetic configurations with very different chaotic plasma edges. A resilient plasma wall interaction pattern was identified across all configurations. This manifests as qualitatively very similar footprint behavior across the different plasma equilibria. Overall, the resilient field lines of interest with high connection length L_C lie within a helical band along the wall for all configurations. This resiliency can be used to identify the best location of a divertor. The details of the magnetic footprint’s resilient helical band is subject to specific field line structures which are linked to the penetration depth of field lines into the plasma and directly influence the heat and particle flux patterns. The differences arising from these details are characterized by introducing a new metric, the minimum radial connection min $$(\delta_N)$$ of a field line from the last closed flux surface. The relationship, namely the deviation from a scaling law, between min $$(\delta_N)$$ and L_C of the field lines in the plasma edge field line behavior suggests that the field lines are associated with structures such as resonant islands, cantori, and turnstiles. This helps determine the relevant magnetic flux channels based on the radial location of these chaotic edge structures and the divertor target footprint. These details will need to be taken into account for resilient divertor design.

View Accepted Manuscript (DOE)

Research Organization:: Univ. of Wisconsin, Madison, WI (United States)

Sponsoring Organization:: USDOE Office of Science (SC), Fusion Energy Sciences (FES)

Grant/Contract Number:: FG02-93ER54222; SC0023548; SC0024548; FG02-95ER54333

OSTI ID:: 3010472

Alternate ID(s):: OSTI ID: 2510946

Journal Information:: Plasma Physics and Controlled Fusion, Journal Name: Plasma Physics and Controlled Fusion Journal Issue: 3 Vol. 67; ISSN 0741-3335; ISSN 1361-6587

Publisher:: IOP ScienceCopyright Statement

Country of Publication:: United States

Language:: English

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