ELM and inter-ELM heat and particle flux to a secondary divertor in the DIII-D tokamak

Perillo, Renato; Boedo, Jose A.; Lasnier, Charles; Rudakov, Dmitry L.; Osborne, Tom H.; Watkins, Jonathan

doi:10.1088/1741-4326/ac0f38

Title: ELM and inter-ELM heat and particle flux to a secondary divertor in the DIII-D tokamak

Journal Article · Fri Jul 16 00:00:00 EDT 2021 · Nuclear Fusion

DOI:https://doi.org/10.1088/1741-4326/ac0f38· OSTI ID:1807533

^[1]; Boedo, Jose A. ^[1]; Lasnier, Charles ^[2];

^[1]; Osborne, Tom H. ^[3]; Watkins, Jonathan ^[4]

Univ. of California, San Diego, La Jolla, CA (United States)
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
General Atomics, San Diego, CA (United States)
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

DIII-D ELMing discharges with a secondary X-point (XPT) inside the vessel were used to evaluate the power distribution between the primary and secondary divertors. The magnetic balance, defined by the distance between the primary and secondary separatrices at the outer midplane (dRsep), was varied from -5 mm (lower-single-null, LSN) to +16 mm (upper-single-null, USN). In this work, we find that the secondary divertor receives up to 1/3 of the total heat flux (primary + secondary divertors), and it is dominated by the ELM-driven flux. Both the radially-integrated and the peak heat flux to the secondary divertor decay below ~50% of the maximum as dRsep is varied from -5 to +6mm, but the integrated heat flux decay flattens out and it would take dRsep above ~25mm to reduce the ELM heat flux to the secondary divertor below 10% of the one deposited to a well-defined SN. Both the secondary inner and outer strike points receive heat flux during ELMs. The peak heat flux is comparable in both strike points for dRsep < 10mm, but the inner strike point receives less than 15% of the total flux. Furthermore, this is experimental evidence that the secondary inner divertor region receives significant ELM flux which should be taken into account for the design of future generation tokamaks.

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Research Organization:: General Atomics, San Diego, CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Sponsoring Organization:: USDOE National Nuclear Security Administration (NNSA)

Grant/Contract Number:: FC02-04ER54698; FG02-07ER54917; AC52-07NA27344

OSTI ID:: 1807533

Alternate ID(s):: OSTI ID: 1877320

Report Number(s):: LLNL-JRNL-836402; TRN: US2212800

Journal Information:: Nuclear Fusion, Vol. 61, Issue 8; ISSN 0029-5515

Publisher:: IOP ScienceCopyright Statement

Country of Publication:: United States

Language:: English

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