Abstract
This article presents a global reduced model for slab-like microtearing modes (MTMs) in the H-mode pedestal, which reproduces distinctive features of experimentally observed magnetic fluctuations, such as chirping and discrete frequency bands at noncontiguous mode numbers. Our model, importantly, includes the global variation of the diamagnetic frequencies, which is necessary to reproduce the experimental observations. The key insight underlying this model is that MTM instability is enabled by the alignment of a rational surface with the peak in the profile of the diamagnetic frequency. Conversely, MTMs are strongly stabilized for toroidal mode numbers for which these quantities are misaligned. This property explains the discrete fluctuation bands in several DIII-D and JET discharges, which we survey using our reduced model in conjunction with global gyrokinetic simulations. A fast yet accurate reduced model for MTMs enables rapid interpretation of magnetic fluctuation data from a wide range of experimental conditions to help assess the role of MTM in the pedestal.
| Original language | English |
|---|---|
| Article number | 042503 |
| Journal | Physics of Plasmas |
| Volume | 29 |
| Issue number | 4 |
| DOIs | |
| State | Published - Apr 1 2022 |
Funding
This research was supported at Oak Ridge National Laboratory supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC05-00OR22725. This material is based upon work supported 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 Award Nos. DE-FC02-04ER54698, DE-AC02-05CH11231, DE-AC02-09CH11466, DE-FG02-04ER54761, and DE-SC0019004. This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014–2018 and 2019–2020 under Grant Agreement No. 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. This work was supported by U.S. DOE Contract No. DE-FG02-04ER54742 at the Institute for Fusion Studies (IFS) at the University of Texas at Austin. This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC05–00OR22725 with the U.S. Department of Energy (DOE). The publisher acknowledges the U.S. government license to provide public access under the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan). This scientific paper has been published as part of the international project co-financed by the Polish Ministry of Science and Higher Education within the program called “PMW” for year.
