First evidence of dominant influence of E × B drifts on plasma cooling in an advanced slot divertor for tokamak power exhaust

Ma, Xinxing; Wang, Huiqian Q.; Guo, Houyang Y.; Stangeby, Peter C.; Meier, E. T.; Shafer, Morgan W.; Thomas, Dan M.

doi:10.1088/1741-4326/abde75

Title: First evidence of dominant influence of E × B drifts on plasma cooling in an advanced slot divertor for tokamak power exhaust

Journal Article · Mon Apr 12 00:00:00 EDT 2021 · Nuclear Fusion

DOI:https://doi.org/10.1088/1741-4326/abde75· OSTI ID:1798817

^[1];

^[2]; Guo, Houyang Y. ^[2]; Stangeby, Peter C. ^[3]; Meier, E. T. ^[4]; Shafer, Morgan W. ^[5]; Thomas, Dan M. ^[2]

Oak Ridge Associated Univ., Oak Ridge, TN (United States)
General Atomics, San Diego, CA (United States)
Univ. of Toronto, ON (Canada)
Univ. of Washington, St. Louis, MO (United States)
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Addressing power exhaust in tokamaks is presently recognized as one of the major remaining open issues for the development of fusion reactors. At the forefront of this endeavor is the effort to develop an advanced divertor by maximizing dissipation of plasma power and momentum inside the divertor. Here, we demonstrate, for the first time, that the electromagnetic (E × B) drifts exert a key influence on plasma and gas dynamics in a new advanced slot divertor in the DIII-D tokamak, named the small angle slot (SAS). SAS leverages the effect of drifts to achieve a highly dissipative divertor with electron temperature T_e ≲ 10 eV over a wide range of plasma densities, for ion B × ∇B away from the divertor, as used for advanced tokamak operation on DIII-D. Modeling with the SOLPS-ITER code shows that for this drift direction, the E × B flow carries particles toward the outer common flux region (CFR) via the private flux region (PFR), reinforcing neutral recycling and enhancing divertor dissipation. In contrast, for the opposite field direction, the E × B flow carries particles away from the outer CFR into the PFR, offsetting the anticipated SAS geometric effects. Furthermore, this finding is an important step in the understanding of the behavior of advanced divertors for achieving a power exhaust solution for fusion reactors.

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Research Organization:: General Atomics, San Diego, CA (United States)

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

Grant/Contract Number:: FC02-04ER54698

OSTI ID:: 1798817

Journal Information:: Nuclear Fusion, Vol. 61, Issue 5; ISSN 0029-5515

Publisher:: IOP ScienceCopyright Statement

Country of Publication:: United States

Language:: English

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