Abstract Details
Abstracts
Author: Seung-Hoe Ku
Requested Type: Poster
Submitted: 2025-03-13 14:31:52
Co-authors: C.S. Chang, R. Hager, L.W. Schmitz, A.O. Nelson
Contact Info:
Princeton Plasma Physics Laboratory
100 Stellarator Rd.
Princeton, NJ 08543
USA
Abstract Text:
To investigate the impact of triangularity on edge plasma properties, gyrokinetic simulations of negative triangularity plasma are performed using the total-f, edge specialized, X-point included gyrokinetic code XGC. A DIII-D-like geometry based on DIII-D negative triangularity discharge #193802 with adjustments for the far scrap-off layer and private flux region is used. A “manufactured” positive triangularity case with the separatrix and limiter/divertor shapes mirrored is also simulated for comparison. Both neoclassical simulations only with n=0 electric field and turbulence simulations are performed. The simulations show that negative triangularity gives a deeper Er well and higher ExB shearing rate than positive triangularity, and that the direction of the toroidal torque from ion orbit loss is opposite from each other. The radial orbit excursion and X-loss hole explain the qualitative behavior of the edge flow generation. The distinct differences in the toroidal rotation profiles at the midplane between deuterium and carbon impurity are explained by the Pfirsch-Schlüter flows. The observed edge Er and the toroidal flow of the carbon impurity at the midplane calculated from the negative triangularity simulation agree qualitatively with experimental measurements. The turbulence intensity of negative triangularity in the scrape-off layer is larger than that of positive triangularity, and the turbulence simulations show ~50% wider heat flux width with negative triangularity than positive triangularity.
This research is based upon work supported by U.S. DOE FES via the DIII-D collaborative research grant to PICSciE, Princeton University, the SciDAC-5 Center for Edge of Tokamak OPtimization (CETOP), University of California Los Angeles, Columbia University under Awards DE-AC02-09CH11466, DE-SC002227, and DE-SC0020287 and the DIII-D national fusion facility under Award DE-FC02-04ER54698. The simulation used resources from NERSC under award FES-ERCAP002368.
Characterization: 2.0
Comments: