H-mode grade confinement in L-mode edge plasmas at negative triangularity on DIII-D

A. Marinoni, M. E. Austin, A. W. Hyatt, M. L. Walker, J. Candy, C. Chrystal, C. J. Lasnier, G. R. McKee, T. Odstrčil, C. C. Petty, M. Porkolab, J. C. Rost, O. Sauter, S. P. Smith, G. M. Staebler, C. Sung, K. E. Thome, A. D. Turnbull, L. Zeng

Research output: Contribution to journalArticlepeer-review

60 Scopus citations

Abstract

Plasmas with a negative triangularity shape have been created on the DIII-D tokamak that, despite maintaining standard L-mode edge radial profiles, reach volume averaged pressure levels typical of H-mode scenarios. Within the auxiliary power available for these experiments, plasmas exhibit near-zero power degradation while sustaining βN = 2.7 and H98,y2 = 1.2 for several energy confinement times. Detailed comparison with matched discharges at positive triangularity indicates that Trapped Electron Modes are weakened at negative triangularity, consistent with increased confinement and reduced intensity of fluctuations in electron density, electron temperature, and ion density. These results indicate that a negative triangularity plasma operating without an edge pedestal might provide an attractive scenario for operations in future reactors.

Original languageEnglish
Article number042515
JournalPhysics of Plasmas
Volume26
Issue number4
DOIs
StatePublished - Apr 1 2019
Externally publishedYes

Funding

The authors wish to thank Dr. F. Turco for the valuable assistance with the CORSICA and DCON codes, as well as Dr. K. H. Burrell, Dr. T. C. Luce, Dr. T. W. Petrie, and Dr. T. L. Rhodes for the useful discussions. This material is based upon the 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 Award Nos. DE-FC02-04ER54698, DE-FG02-94ER54235, DE-FC02-99ER54512, and DE-SC0016154. DIII-D data shown in this paper can be obtained in digital format by following the links at https://fusion.gat.com/global/D3DDMP. TRANSP simulations were performed on the PPPL cluster using version 2018-1.0, DOI: 10.11578/dc.20180627.4. Part of the data analysis was performed using the OMFIT framework.

FundersFunder number
DOE Office of Science
U.S. Department of Energy
Office of Science
Fusion Energy Sciences

    Fingerprint

    Dive into the research topics of 'H-mode grade confinement in L-mode edge plasmas at negative triangularity on DIII-D'. Together they form a unique fingerprint.

    Cite this