Abstract
Experimental data on electromagnetic fluctuations in DIII-D, made available by the Faraday-effect radial interferometer-polarimeter (RIP) diagnostic Chen (2016 Rev. Sci. Instrum. 87 11E108), is examined in comparison with detailed gyrokinetic simulations using gyrokinetic electromagnetic numerical experiment (GENE). The diagnostic has the unique capability of making internal measurements of fluctuating magnetic fields ∫ n e δ B r d R ∫ n e d R . Local linear simulations identify microtearing modes (MTMs) over a substantial range of toroidal mode numbers (peaking at n = 15) with frequencies in good agreement with the experimental data. Local nonlinear simulations reinforce this result by producing a magnetic frequency spectrum in good agreement with that diagnosed by RIP. Simulated heat fluxes are in the range of experimental expectations. However, magnetic fluctuation amplitudes are substantially lower than the experimental expectations. Possible sources of this discrepancy are discussed, notably the fact that the diagnostics are localized at the mid-plane—the poloidal location where the simulations predict the fluctuation amplitudes to be smallest. Despite some discrepancies, several connections between simulations and experiments, combined with general criteria discriminating between potential pedestal instabilities, strongly point to MTMs as the source of the observed magnetic fluctuations.
| Original language | English |
|---|---|
| Article number | 126061 |
| Journal | Nuclear Fusion |
| Volume | 62 |
| Issue number | 12 |
| DOIs | |
| State | Published - Dec 2022 |
Funding
Thanks to the fruitful discussions with Tao Xie, and Joel Larakers. This material is based upon work supported by the US 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 Award(s): DE-FC02-04ER54698, DE-SC0022164, DE-AC02-05CH11231, DE-SC0019004, This work was supported by US DOE Contract No. DE-FG02-04ER54742 at the Instituted for Fusion Studies (IFS) at the University of Texas at Austin. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility. We acknowledge the CINECA award under the ISCRA initiative, for the availability of high performance computing resources and support. This research was supported at Oak Ridge National Laboratory supported by the Office of Science of the US Department of Energy under Contract No. DE-AC05-00OR22725. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility, and the Texas Advanced Computing Center (TACC) at The University of Texas at Austin. Thanks to the fruitful discussions with Tao Xie, and Joel Larakers. This material is based upon work supported by the US 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 Award(s): DE-FC02-04ER54698, DE-SC0022164, DE-AC02-05CH11231, DE-SC0019004, This work was supported by US DOE Contract No. DE-FG02-04ER54742 at the Instituted for Fusion Studies (IFS) at the University of Texas at Austin. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility. We acknowledge the CINECA award under the ISCRA initiative, for the availability of high performance computing resources and support. This research was supported at Oak Ridge National Laboratory supported by the Office of Science of the US Department of Energy under Contract No. DE-AC05-00OR22725. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility, and the Texas Advanced Computing Center (TACC) at The University of Texas at Austin.
Keywords
- DIII-D
- diagnostic
- gyrokinetic
- microtearing mode
- nonlinear simulations
- pedestal
- polarimeter
