Abstract Details
Abstracts
Author: Robert Hager
Requested Type: Pre-Selected Invited
Submitted: 2019-02-22 22:17:45
Co-authors: C. S. Chang, N. M. Ferraro, R. Nazikian
Contact Info:
Princeton Plasma Physics Laboratory
100 Stellarator Road
Princeton, New Jersey 08540
USA
Abstract Text:
Plasma density and heat transport caused by resonant magnetic perturbations (RMPs) is studied in a model DIII-D discharge with advanced coupled gyrokinetic-MHD simulation. RMP has been accepted into the ITER design as the primary control tool to suppress edge localized modes (ELMs). Strong RMPs, however, often reduce edge particle confinement (pump-out), which degrades fusion efficiency, but not always accompanied by heat loss. In our advanced model, the perturbed equilibrium is calculated with the M3D-C1 code. This equilibrium (including the RMP) is coupled into the edge gyrokinetic XGC suite of codes, which calculate neoclassical and turbulent transport of ions and electrons. Evolution of background plasma and ExB profile is included together with neutral particle and X-point orbit loss physics. We find a significant increase in the neoclassical radial particle fluxes to a level similar to experimental observation. This increased particle flux is accompanied by an electron heat pinch just inside the separatrix, which agrees qualitatively with long-unexplained experimental observations. Nonlinear phase-space dynamics in the presence of the RMP field appears to be responsible for the electron heat-pinch. Previous XGC1 simulations with adiabatic electrons exhibited a higher edge turbulence intensity due to RMPs, mostly from the weakening of the ExB shearing rate, which was not enough to explain the density pump-out without the nonlinear neoclassical electron dynamics discussed here.
Work supported by the U.S. DOE under contracts DE-AC02-09CH11466 (PPPL) and DE-FC02-04ER54698 (DIII-D), and by ALCF and NERSC for computing resources.
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