Validation of nonlinear gyrokinetic simulations of L- and I-mode plasmas on Alcator C-Mod
Abstract
New validation of global, nonlinear, ion-scale gyrokinetic simulations (GYRO) is carried out for L- and I-mode plasmas on Alcator C-Mod, utilizing heat fluxes, profile stiffness, and temperature fluctuations. Previous work at C-Mod found that ITG/TEM-scale GYRO simulations can match both electron and ion heat fluxes within error bars in I-mode [White PoP 2015], suggesting that multi-scale (cross-scale coupling) effects [Howard PoP 2016] may be less important in I-mode than in L-mode. New results presented here, however, show that global, nonlinear, ion-scale GYRO simulations are able to match the experimental ion heat flux, but underpredict electron heat flux (at most radii), electron temperature fluctuations, and perturbative thermal diffusivity in both L- and I-mode. Linear addition of electron heat flux from electron scale runs does not resolve this discrepancy. These results indicate that single-scale simulations do not sufficiently describe the I-mode core transport, and that multi-scale (coupled electron- and ion-scale) transport models are needed. A preliminary investigation with multi-scale TGLF, however, was unable to resolve the discrepancy between ion-scale GYRO and experimental electron heat fluxes and perturbative diffusivity, motivating further work with multi-scale GYRO simulations and a more comprehensive study with multi-scale TGLF.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Mar 02, 2017
- Source ID
- 10.1063/1.4977466
Entities
People
- A. E. Hubbard
- A. E. White
- Alexander Creely
- Cynthia Sung
- G. D. Conway
- G. M. Staebler
- J. Candy
- J.E. Rice
- Jerry Hughes
- N. Cao
- N. T. Howard
- P Rodriguez-Fernandez
- S. J. Freethy
Organizations
- General Atomics
- Massachusetts Institute of Technology
- Max Planck Institute of Plasma Physics
- United States Department of Defense
- United States Department of Energy
- University of California, Los Angeles