Abstract
In this study, gyrokinetic simulations are used to study pedestal fluctuations for DIII-D discharge 174082 using the GENE code. Nonlinear local simulations indicate that electron heat flux has contributions from electron temperature gradient-driven transport but at levels insufficient to satisfy power balance. We show that microtearing modes (MTM) and neoclassical transport are likely to account for the remaining observed energy losses in the electron and ion channels, respectively. The MTM instabilities found in the simulations are consistent with the high-frequency fluctuations identified in the magnetic fluctuation data from Mirnov coils. The fluctuation data in this discharge also exhibit a low-frequency band of fluctuations. By modifying the equilibrium profiles and plasma β, simulations produce MHD modes, which may be responsible for these observed low-frequency fluctuations. We compare several metrics involving ratios of fluctuation amplitudes and transport quantities for both MTMs and MHD modes. This analysis suggests that the available data are consistent with the simultaneous activity of both MHD modes and MTMs provided that the former is limited largely to the particle transport channel.
| Original language | English |
|---|---|
| Article number | 112505 |
| Journal | Physics of Plasmas |
| Volume | 29 |
| Issue number | 11 |
| DOIs | |
| State | Published - Nov 2022 |
Funding
This work is supported by U.S. DOE under Grant Nos. DE-FC02-04ER54698, DE-FG02-97ER54415, DE-AC02-09CH11466, and DE-SC0022164. A portion of this study's data analysis was performed using the OMFIT integrated modeling framework. 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 report was prepared as an account of work sponsored by an agency of the U.S. government. Neither the U.S. government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the U.S. government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the U.S. government or any agency thereof.
| Funders | Funder number |
|---|---|
| U.S. Department of Energy | DE-AC05-00OR22725, DE-SC0022164, DE-AC02-09CH11466, DE-FC02-04ER54698, DE-FG02-97ER54415 |
