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Title: Overview of NSTX Upgrade initial results and modelling highlights

The National Spherical Torus Experiment (NSTX) has undergone a major upgrade, and the NSTX Upgrade (NSTX-U) Project was completed in the summer of 2015. NSTX-U first plasma was subsequently achieved, diagnostic and control systems have been commissioned, the H-mode accessed, magnetic error fields identified and mitigated, and the first physics research campaign carried out. During ten run weeks of operation, NSTX-U surpassed NSTX record pulse-durations and toroidal fields (TF), and high-performance ~1 MA H-mode plasmas comparable to the best of NSTX have been sustained near and slightly above the n = 1 no-wall stability limit and with H-mode confinement multiplier H 98y,2 above 1. Transport and turbulence studies in L-mode plasmas have identified the coexistence of at least two ion-gyro-scale turbulent micro-instabilities near the same radial location but propagating in opposite (i.e. ion and electron diamagnetic) directions. These modes have the characteristics of ion-temperature gradient and micro-tearing modes, respectively, and the role of these modes in contributing to thermal transport is under active investigation. The new second more tangential neutral beam injection was observed to significantly modify the stability of two types of Alfven eigenmodes. Improvements in offline disruption forecasting were made in the areas of identification of rotating MHDmore » modes and other macroscopic instabilities using the disruption event characterization and forecasting code. Finally, the materials analysis and particle probe was utilized on NSTX-U for the first time and enabled assessments of the correlation between boronized wall conditions and plasma performance. These and other highlights from the first run campaign of NSTX-U are described.« less
Authors:
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  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  2. Univ. of Illinois, Urbana-Champaign, IL (United States)
  3. Columbia Univ., New York, NY (United States)
  4. Univ. of California, Los Angeles, CA (United States)
  5. Univ. of Wisconsin, Madison, WI (United States)
  6. Univ. of California, Irvine, CA (United States)
  7. Univ. of Washington, Seattle, WA (United States)
  8. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  9. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  10. Nova Photonics, Princeton, NJ (United States)
  11. Univ. of California, Davis, CA (United States)
  12. Princeton Univ., NJ (United States)
  13. General Atomics, San Diego, CA (United States)
  14. The College of New Jersey, Ewing, NJ (United States)
  15. Johns Hopkins Univ., Baltimore, MD (United States)
  16. Univ. of Tennessee, Knoxville, TN (United States)
  17. X Science LLC, Plainsboro, NJ (United States)
  18. College of William and Mary, Williamsburg, VA (United States)
  19. Lodestar Research Corporation, Boulder, CO (United States)
  20. Univ. of Michigan, Ann Arbor, MI (United States)
  21. Lehigh Univ., Bethlehem, PA (United States)
Publication Date:
Grant/Contract Number:
AC02-09CH11466
Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 57; Journal Issue: 10; Related Information: Please use this identifier to cite or link to this item: http://arks.princeton.edu/ark:/88435/dsp016w924f316; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Research Org:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; NSTX-U; Spherical tokamak; Alfven Eigenmodes
OSTI Identifier:
1367916