Abstract Details
Abstracts
Author: Jessica L. Li
Requested Type: Poster
Submitted: 2023-03-31 21:35:21
Co-authors: A.Reiman, M.Zarnstorff, C.S.Chang
Contact Info:
Princeton Plasma Physics Laboratory
100 Stellarator Rd
Princeton, NJ 08540
USA
Abstract Text:
Negative triangularity shaping of tokamak plasmas has been demonstrated to improve heat confinement both experimentally and numerically. This is theorized to be due to stabilization of ion-scale microinstabilities, leading to the suppression of turbulent transport. We investigate the stability properties of collisionless ion-temperature-gradient (ITG), trapped-electron-mode (TEM), and kinetic-ballooning-mode (KBM) instabilities in axisymmetric equilibria. The global electromagnetic gyrokinetic code XGC is used to simulate up-down symmetric positive- and negative-triangularity geometries of DIII-D-like equilibria at varying temperature and density profiles and plasma beta. We compare critical gradients, growth rates, and stability boundaries of these collisionless microinstabilities to study the strength and extent of the negative-triangularity-driven stabilization mechanism in different regimes. At low beta, kinetic electron simulations find that both ITG and TEM are linearly stabilized by negative triangularity, and this effect can only be captured in simulations with nonzero beta. We also examine the effectiveness of this turbulence suppression mechanism over a range of plasma beta, including at reactor-relevant levels.
Comments: