Role of poloidal E × B drift in divertor heat transport in DIII-D

Aaro E. Järvinen*, S.L. Allen, A. W. Leonard, A.G. McLean, A.L. Moser, T.D. Rognlien, C. M. Samuell

*Corresponding author for this work

    Research output: Contribution to journalArticleScientificpeer-review

    13 Citations (Scopus)

    Abstract

    Simulations for DIII-D high confinement mode plasmas with the multifluid code UEDGE show a strong role of poloidal E × B drifts on divertor heat transport, challenging the paradigm of conduction-limited scrape-off layer (SOL) transport. While simulations with reduced drift magnitude are well aligned with the assumption that electron heat conduction dominates the SOL heat transport, simulations with drifts predict that the poloidal convective E × B heat transport dominates over electron heat conduction in both attached and detached conditions. As poloidal E × B flow propagates across magnetic field lines, poloidal transport with shallow magnetic pitch angles can reach values that are of the same order as would be provided by sonic flows parallel to the field lines. These flows can lead to strong convection-dominated divertor heat transport, increasing the poloidal volume of radiative power front, consistent with previous measurements at DIII-D. Due to these convective flows, the Lengyel integral approach, assuming zero convective fraction, is expected to provide a pessimistic estimate for the radiative capability of impurities in the divertor. For the DIII-D simulations shown here, the Lengyel integral approach underestimates the radiated power by a factor of 6, indicating that, for reliable DIII-D divertor power exhaust predictions, full two-dimensional (2D) calculations, including drifts, would be necessary.

    Original languageEnglish
    Article numbere201900111
    JournalContributions to Plasma Physics
    Volume60
    Issue number5-6
    DOIs
    Publication statusPublished - 1 Jun 2020
    MoE publication typeA1 Journal article-refereed

    Funding

    This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences, using the DIII-D National Fusion Facility, a DOE Office of Science user facility, under Awards DE-FC02-04ER54698, DE-AC52-07NA27344, and LLNL LDRD project 17-ERD-020.

    Keywords

    • conduction
    • convection
    • divertor
    • drifts
    • heat transport
    • radiation

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