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Multi-device studies of pedestal physics and confinement in the I-mode regime

Journal Article · · Nuclear Fusion
 [1];  [2];  [3];  [4];  [5];  [6];  [7];  [8];  [3];  [6];  [2];  [2];  [3];  [9];  [10];  [6];  [3];  [9];  [9];  [3] more »;  [11];  [12];  [9];  [12];  [13];  [3];  [9];  [9];  [9];  [9];  [3];  [11] « less
  1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); General Atomics
  2. General Atomics, San Diego, CA (United States)
  3. Max-Planck-Institut fur Plasmaphysik, Garching (Germany)
  4. Univ. of Texas, Austin, TX (United States)
  5. Max-Planck-Institut fur Plasmaphysik, Garching (Germany); EUROfusion - Programme Management Unit, Garching (Germany)
  6. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  7. Univ. of California San Diego, La Jolla, CA (United States); Univ. of York, York (United Kingdom)
  8. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  9. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  10. ITER Organization, St. Paul Lez Durance Cedex (France)
  11. Univ. of Wisconsin, Madison, WI (United States)
  12. Univ. of California, Los Angeles, CA (United States)
  13. Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne (Switzerland)
+ Show Author Affiliations
This paper describes joint ITPA studies of the I-mode regime, which features an edge thermal barrier together with L-mode-like particle and impurity transport and no Edge Localized Modes (ELMs). The regime has been demonstrated on the Alcator C-Mod, ASDEX Upgrade and DIII-D tokamaks, over a wide range of device parameters and pedestal conditions. Dimensionless parameters at the pedestal show overlap across devices and extend to low collisionality. When they are matched, pedestal temperature profiles are also similar. Pedestals are stable to peeling ballooning modes, consistent with lack of ELMs. Access to Imode is independent of heating method (neutral beam injection, Ion Cyclotron and/or Electron Cyclotron Resonance Heating). Normalized energy confinement H98,y2 ≥ 1 has been achieved for a range of 3 ≤ q95 ≤ 4.9 and scales favourably with power. Changes in turbulence in the pedestal region accompany the transition from L-mode to I-mode. The L-I threshold increases with plasma density and current, and with device size, but has a weak dependence on toroidal magnetic field BT. The upper limit of power for I-modes, which is set by I-H transitions, increases with BT and the power range is largest on Alcator C-Mod at B > 5 T. Finally, issues for extrapolation to ITER and other future fusion devices are discussed.
Research Organization:
General Atomics, San Diego, CA (United States); Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
Sponsoring Organization:
USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Fusion Energy Sciences (FES); USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
Contributing Organization:
Alcator C-Mod, ASDEX Upgrade and DIII-D Teams
Grant/Contract Number:
AC02-09CH11466; AC52-07NA27344; FC02-04ER54698; FG02-08ER54984; FG02-08ER54999; FG02-89ER53296; FG02-94ER54235; SC0012469
OSTI ID:
1373884
Alternate ID(s):
OSTI ID: 1871410
OSTI ID: 1375941
OSTI ID: 1260287
Report Number(s):
LLNL-JRNL-834529
Journal Information:
Nuclear Fusion, Journal Name: Nuclear Fusion Journal Issue: 8 Vol. 56; ISSN 0029-5515
Publisher:
IOP ScienceCopyright Statement
Country of Publication:
United States
Language:
English

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Cited By (11)

Verification of GENE and GYRO with L-mode and I-mode plasmas in Alcator C-Mod journal April 2018
Gyrokinetic investigation of the ASDEX Upgrade I-mode pedestal journal December 2019
Effects of zonal flows on transport crossphase in dissipative trapped-electron mode turbulence in edge plasmas journal July 2019
Scale selection and feedback loops for patterns in drift wave-zonal flow turbulence journal August 2019
Access and sustainment of naturally ELM-free and small-ELM regimes journal September 2018
Up/down impurity density asymmetries in C-Mod plasmas journal September 2018
Assessment of the baseline scenario at q 95 ~ 3 for ITER journal September 2018
Radiative heat exhaust in Alcator C-Mod I-mode plasmas journal March 2019
Scaling laws from theory-based modeling for different regimes in the DEMO fusion reactor journal July 2019
I-mode investigation on the Experimental Advanced Superconducting Tokamak journal July 2019
Effects of zonal flows on transport crossphase in dissipative trapped-electron mode turbulence in edge plasmas text January 2019

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Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
FEC 2014
I-mode
pedestal
threshold
tokamak