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The causes of the disruptive tearing instabilities of the ITER Baseline Scenario in DIII-D

Journal Article · · Nuclear Fusion
 [1];  [2];  [2];  [2];  [3];  [3]
  1. Columbia Univ., New York, NY (United States); General Atomics, DIII-D, Technical Publications
  2. General Atomics, San Diego, CA (United States)
  3. Columbia Univ., New York, NY (United States)
Analysis of the evolving current density (J), pedestal and rotation profiles in a database of 200 ITER Baseline Scenario (IBS) demonstration discharges in the DIII-D tokamak identifies the current profile as a key determinant of the disruptive instability limiting both high and low torque operation of these q95=3 plasmas. The m=2/n=1 tearing modes, occurring after several pressure-relaxation times, are linked to the shape of the current profile in the outer region of the plasma. The q=2 surface is located at r~0.78, near a minimum in J. A steeper "well" around the q=2 surface is correlated with the instabilities, and this finding is consistent for modes that occur both early (<1 TR) and late (>2 TR) on the βN flattop, at high and low input torque, for discharges with and without direct electron heating. Low rotation or differential rotation in the core plasmas is shown to not be the direct cause of the onset of these instabilities. The current profile trends identified in this work indicate that the modes limiting the Q=10 operation in the ITER demonstration plasmas are likely due to the slow evolution of the current profile, and reveal which shape of the current profile is more prone to the 2/1 tearing instability.
Research Organization:
General Atomics, San Diego, CA (United States)
Sponsoring Organization:
USDOE Office of Nuclear Energy (NE)
Grant/Contract Number:
FC02-04ER54698; FG02-04ER54761
OSTI ID:
1470983
Alternate ID(s):
OSTI ID: 22929523
Journal Information:
Nuclear Fusion, Journal Name: Nuclear Fusion Journal Issue: 10 Vol. 58; ISSN 0029-5515
Publisher:
IOP ScienceCopyright Statement
Country of Publication:
United States
Language:
English

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Cited By (3)

DIII-D research towards establishing the scientific basis for future fusion reactors journal June 2019
Progress in disruption prevention for ITER journal June 2019
On the triggerless onset of 2/1 neoclassical tearing modes in TCV journal December 2019