Stationary I-modes in multiple configurations in the DIII-D tokamak

POSTER

Abstract

By using β feedback to compensate for improving τE, longer, more stationary I-modes were obtained than in past DIII-D experiments. These experiments were conducted as part of the 2022 Joint Research Target campaign on intrinsically non-ELMing enhanced confinement regimes. I-modes feature a temperature pedestal but low particle confinement. Configurations tested were a LSN, low triangularity δ shape matching an ASDEX Upgrade I-mode discharge and a higher δ USN shape with better pumping in the closed divertor. Both had B×∇B drifts away from the X-point, as usual for I-mode. In the LSN shape, the upper limit for heating power (3.5 MW) and pressure (βN=1) was set by I-H transitions. In the USN shape, it was limited by available power (11 MW NBI) and βN as high as1.6 was achieved. Te and Ti pedestals formed in both configurations, with negligible changes in density from L-mode. The Weakly Coherent Mode has not yet been identified in these discharges; further analysis is ongoing. Many other turbulence and fluctuations changes were observed, including a reduction of density fluctuations at intermediate k, a decrease of magnetic turbulence at 100-500 kHz, and bursts of n~20 MHD in Te on ECE Imaging.

*Worked funded by U.S. Department of Energy, DE-SC0014264, DE-FC02-04ER54698, DE-FG02-99ER54531, DE-SC0019352, DE-SC0019004

Presenters

  • Amanda E Hubbard

    • Massachusetts Institute of Technology, PSFC
    • Massachusetts Institute of Technology
    • Massachusetts Institute of Technology MIT

Authors

  • Amanda E Hubbard

    • Massachusetts Institute of Technology, PSFC
    • Massachusetts Institute of Technology
    • Massachusetts Institute of Technology MIT

  • Adrianna Angulo

    • Princeton Plasma Physics Laboratory

  • Max E Austin

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

  • Amelia Cavallaro

    • Massachusetts Institute of Technology

  • Jie Chen

    • University of California, Los Angeles

  • Colin Chrystal

    • General Atomics - San Diego

  • Tim Happel

    • Max Planck Institute for Plasma Physics

  • Shaun R Haskey

    • Princeton Plasma Physics Laboratory

  • Rongjie Hong

    • University of California, Los Angeles
    • UCLA

  • Jerry W Hughes

    • MIT Plasma Science and Fusion Center
    • MIT PSFC

  • George R McKee

    • University of Wisconsin - Madison
    • UWisc. Madison

  • Andrew O Nelson

    • Columbia University

  • Tom H Osborne

    • General Atomics
    • General Atomics - San Diego

  • Aaron M Rosenthal

    • Massachusetts Institute of Technology MI

  • Terry L Rhodes

    • University of California, Los Angeles

  • Theresa M Wilks

    • MIT-PSFC
    • MIT

  • Guanying Yu

    • University of California, Davis

  • Shawn A Zamperini

    • General Atomics

  • Yilun Zhu

    • University of California, Davis