No Access Submitted: 14 August 2020 Accepted: 21 September 2020 Published Online: 16 October 2020
Physics of Plasmas 27, 102511 (2020); https://doi.org/10.1063/5.0025357
A toroidal asymptotic matching model of the response of a tokamak plasma to a static resonant magnetic perturbation (RMP) is used to simulate the n =3 RMP-induced edge-localized-mode-suppression windows in q95 that are evident when the plasma current is slowly ramped in DIII-D discharge #145380. All quantities employed in the simulation are derived from experimental measurements, apart from the neutral particle data. Three cases are considered. In the first case, the natural frequencies of tearing modes resonant in the plasma are determined by the ion flows at the corresponding resonant surfaces, which is the prediction of nonlinear tearing mode theory. In the second case, the natural frequencies are determined by the local E × B velocities at the resonant surfaces. In the third case, the natural frequencies are determined by the electron flows at the resonant surfaces, which is the prediction of linear tearing mode theory. The second case gives the best agreement between the simulations and the experimental observations. The first and third cases only lead to partial agreement between the simulations and the observations. In the first case, the lack of complete agreement may be a consequence of using an inaccurate assumption for the neutral particle distribution in the pedestal. In the third case, the lack of complete agreement is probably due to the fact that the response of a tokamak plasma to an RMP is not accurately described by linear tearing mode theory.
The author would like to thank Q. M. Hu and R. Nazikian for providing the experimental data used in this paper. The author would also like to thank J.-K. Park and N. C. Logan for providing guidance on how to run the GPEC code. Finally, the author would like to thank C. Paz-Solden, B. A. Grierson, and W. M. Solomon for helpful comments during the preparation of this paper.
This research was directly funded by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences, under Contract No. DE-FG02–04ER54742, and incorporates work funded by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences, using the DIII-D National Fusion Facility, a DOE Office of Science user facility, under Contract No. DE-FC02–04ER54698.
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