Abstract Details
Abstracts
Author: Joey M Duff
Requested Type: Poster
Submitted: 2023-03-30 13:55:10
Co-authors: B.J. Faber, C.C. Hegna, M.J. Pueschel, P.W. Terry
Contact Info:
University of Wisconsin-Madison
1500 Engineering Dr
Madison, WI 53706
USA
Abstract Text:
Advances in stellatator optimization have been successfully leveraged to find new stellarator configurations with enhanced confinement of collisionless particle trajectories [1]. A subsequent goal of stellarator optimization is to find stellarator configurations that also reduce turbulent transport using three-dimensional (3D) shaping. Trapped-electron-mode (TEM) turbulence can play a significant role in quasi-symmetric stellarators [2]. One way to improve the turbulent transport properties of tokamak plasmas is through negative flux-surface triangularity [3]. Nonlinear gyrokinetic simulations suggests that the heat flux of TEM turbulence correlates with the free energy available in background temperature and density gradients, as quantified by an available-energy metric [4]. In this work, we address the possibility of using negative triangularity as a mechanism to reduce TEM turbulence in stellarator plasmas. Towards this end, a new optimization framework is developed using local 3D MHD equilibrium solutions [5]. This approach has been successfully employed to improve the quasi-symmetry properties—a metric for reducing neoclassical transport—while simultaneously reducing the available-energy metric for local 3D MHD equilibria for a helically-rotating negative triangularity stellarator. The gyrokinetic code GENE is then employed to assess the local TEM linear characteristics. These insights help improve reduced models for TEM fluxes in ensuing optimization calculations.
References:
[1] A. Bader et al., J. Plasma Phys. 86 (2020)
[2] B. Faber et al., Phys. Plasmas 22 (2015)
[3] A. Pochelon et al., Nucl. Fusion 47 (1999)
[4] R. J. J . Mackenbach et al., Phys. Rev. Lett. 128 (2022)
[5] J. M. Duff et al., Phys. Plasmas 29 (2022)
Comments: