Diverted Negative Triangularity plasmas on DIII–D: The benefit of high confinement without the liability of an edge pedestal

Marinoni, Alessandro; Austin, Max E.; Hyatt, A. W.; Saarelma, Samuli; Scotti, Filippo; Yan, Zheng; Chrystal, Colin; Coda, Stefano; Glass, F.; Hanson, Jeremy; McLean, Adam G.; Pace, David C.; Paz-Soldan, Carlos; Petty, Craig; Porkolab, Miklos; Schmitz, Lothar; Sciortino, Francesco; Smith, Sterling P.; Thome, Kathreen E.; Turco, Francesca

doi:10.1088/1741-4326/ac1f60

Diverted Negative Triangularity plasmas on DIII–D: The benefit of high confinement without the liability of an edge pedestal

Journal Article · Thu Sep 23 00:00:00 EDT 2021 · Nuclear Fusion

DOI:https://doi.org/10.1088/1741-4326/ac1f60· OSTI ID:1818291

^[1]; Austin, Max E. ^[2]; Hyatt, A. W. ^[3]; Saarelma, Samuli ^[4]; Scotti, Filippo ^[5]; Yan, Zheng ^[6]; ^[3]; ^[7]; Glass, F. ^[3]; Hanson, Jeremy ^[8]; McLean, Adam G. ^[5]; Pace, David C. ^[3]; ^[8]; ^[3]; Porkolab, Miklos ^[9]; ^[10]; ^[9]; Smith, Sterling P. ^[3]; ^[3]; Turco, Francesca ^[8]

Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); General Atomics
Univ. of Texas, Austin, TX (United States)
General Atomics, San Diego, CA (United States)
UKAEA Culham, Oxfordshire (United Kingdom)
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Univ. of Wisconsin, Madison, WI (United States)
EPFL, Lausanne (Switzerland)
Columbia Univ., New York, NY (United States)
Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Univ. of California, Los Angeles, CA (United States)

Diverted discharges at negative triangularity on the DIII-D tokamak sustain normalized confinement and pressure levels typical of standard H-mode scenarios (H_98y,2≅1, β_N≅3) without developing an edge pressure pedestal, despite the auxiliary power far exceeding the L → H power threshold expected from conventional scaling laws. The power degradation of confinement is substantially weaker than the ITER-89P scaling, resulting in a confinement factor that improves with increasing auxiliary power. Furthermore, the absence of the edge pedestal is beneficial in several aspects, such as eliminating the need for active mitigation or suppression of edge localized modes, low impurity retention and a reconstructed scrape-off layer heat flux width at the mid-plane that exceeds the ITPA multi-machine scaling law by up to 50%. Together with technological advantages granted by placing the divertor at larger radii, plasmas at Negative Triangularity without an edge pedestal feature both core confinement and power handling characteristics that are potentially suitable for operation in future fusion reactors.

View Accepted Manuscript (DOE)

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

Sponsoring Organization:: USDOE

Grant/Contract Number:: FC02-04ER54698

OSTI ID:: 1818291

Alternate ID(s):: OSTI ID: 1873629

Journal Information:: Nuclear Fusion, Journal Name: Nuclear Fusion Journal Issue: 11 Vol. 61; ISSN 0029-5515

Publisher:: IOP ScienceCopyright Statement

Country of Publication:: United States

Language:: English

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