The root cause of disruptive NTMs and paths to stable operation in DIII-D ITER baseline scenario plasmas
[1];
[2];
[3];
[4];
[6]
- General Atomics, San Diego, CA (United States); University of California, Irvine, CA (United States); General Atomics
- Oak Ridge Associated Universities (ORAU), Oak Ridge, TN (United States)
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Columbia University, New York, NY (United States)
- General Atomics, San Diego, CA (United States)
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
- Massachusetts Institute of Technology (MIT), Cambridge, MA (United States)
Analyses of the DIII-D ITER Baseline Scenario database support that the disruptive m,n=2,1 magnetic islands are pressure gradient driven, non-linear instabilities seeded in a sequence of stochastic transient magnetic perturbations, and that the current profile relaxation does not affect the m,n=2,1 island onset rate. At low torque, these Neoclassical Tearing Modes are most commonly seeded by non-linear 3-wave coupling when the differential rotation between the q=1 & q=2 rational surfaces approaches zero. Lack of statistically significant difference between the current profiles of stable and unstable states, as well as lack of correlation between the tearing mode onset rate and the current profile relaxation both reject causality between the current profile evolution and the 2,1 magnetic island onsets in these plasmas. These support that preserving the differential rotation between the q=1 and q=2 rational surfaces is key to long pulse stable operation in the plasma scenario planned for ITER, while optimization of the current profile within the explored parameter space may lead to much weaker improvements than sustaining the differential rotation.
- 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), Basic Energy Sciences (BES). Scientific User Facilities (SUF); USDOE Office of Science (SC), Fusion Energy Sciences (FES)
- Grant/Contract Number:
- AC52-07NA27344; FC02-04ER54698; SC0014264; SC0022270
- OSTI ID:
- 2468698
- Report Number(s):
- LLNL--JRNL-2001071
- Journal Information:
- Nuclear Fusion, Journal Name: Nuclear Fusion Journal Issue: 12 Vol. 64; ISSN 0029-5515
- Publisher:
- IOP ScienceCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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