Highlights from the DIII-D Negative Triangularity Campaign

ORAL

Abstract

A dedicated DIII-D negative triangularity (NT) campaign produced over 500 strongly shaped (δ ~ -0.5), diverted NT discharges. These plasmas demonstrate simultaneous access to high normalized current, pressure, density, and confinement – indicating a wide operating space with surprisingly good core stability properties. q95 < 3, bN ~ 3, Greenwald fractions (fGW) ~ 1, and H98 ~ 1 are simultaneously observed. The confinement time is found to have a linear dependence on plasma current, significant power degradation, and is reduced at low rotation. Long-duration hybrid-like stationary scenarios with H98~0.95 are accessed. All results are found together with a robustly stable NT edge free from edge-localized modes, despite edge and average pressures comparable to standard DIII-D plasmas without ELMs, and are consistent with a pedestal gradient limited by high-n ballooning modes. Detachment was accessed despite the divertor being open and with short connection length. Together with inherently peaked density profiles, detachment without impurities occurred with fGW approaching and above unity. Core impurity seeding with Ne, Ar, and Kr enabled access to high radiative-fraction, providing confidence that core-edge integration will be facilitated by reduced exhaust power in NT scenarios.

*This work was supported by the US DOE under the following Awards DE-FC02-04ER54698, DE-FG02-97ER54415, DE-SC0019302, DE-SC0020287, DE-FG02-08ER54999, DE-AC52-07NA27344, DE-SC0022270, DE-SC0016154, DE-SC0014264, and DE-SC0023100.

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Presenters

  • Carlos A Paz-Soldan

    • Columbia University

Authors

  • Carlos A Paz-Soldan

    • Columbia University

  • Max E Austin

    • University of Texas at Austin
    • University of Texas – Austin

  • J. L Barr

    • General Atomics - San Diego
    • General Atomics

  • William Boyes

    • Columbia University

  • Livia Casali

    • University of Tennessee Knoxville

  • Colin Chrystal

    • General Atomics - San Diego

  • Tyler B Cote

    • General Atomics

  • Siye Ding

    • General Atomics

  • Xiaodi Du

    • General Atomics - San Diego

  • David Eldon

    • General Atomics - San Diego
    • General Atomics

  • Darin R Ernst

    • Massachusetts Institute of Technology MIT
    • Massachusetts Institute of Technology MI

  • Rongjie Hong

    • UCLA

  • Filipp Khabanov

    • University of Wisconsin-Madison
    • NRC 'Kurchatov Institute'
    • University of Wisconsin - Madison

  • Priyansh Lunia

    • Columbia University

  • Alessandro Marinoni

    • Massachusetts Institute of Technology MIT

  • Ray Mattes

    • University of Tennessee Knoxville
    • University of Tennessee
    • University of Tennessee-Knoxville

  • George R McKee

    • University of Wisconsin - Madison
    • UWisc. Madison

  • Saskia Mordijck

    • College of William and Mary

  • Andrew O Nelson

    • Columbia University

  • Tom H Osborne

    • General Atomics
    • General Atomics - San Diego

  • Olivier Sauter

    • EPFL
    • Ecole Polytechnique Federale de Lausanne
    • Swiss Plasma Center
    • EPFL-SPC

  • Daisuke Shiraki

    • Oak Ridge National Lab
    • Oak Ridge National Laboratory
    • General Atomics - San Diego

  • Lothar Schmitz

    • University of California, Los Angeles

  • Filippo Scotti

    • Lawrence Livermore Natl Lab

  • Samuel Stewart

    • University of Wisconsin - Madison
    • University of Wisconsin-Madison

  • Kathreen E Thome

    • General Atomics

  • Austin Welsh

    • University of Tennessee Knoxville
    • University of Tennessee-Knoxville

  • Haley S Wilson

    • Columbia University

  • Theresa M Wilks

    • MIT-PSFC
    • MIT