Abstract Details
Abstracts
Author: Adelle M. Wright
Requested Type: Consider for Invited
Submitted: 2026-02-24 14:17:19
Co-authors: B. J. Faber
Contact Info:
University of Wisconsin - Madison
1500 Engineering Dr
Madison, WI 53706
USA
Abstract Text:
Maximizing particle and energy confinement is crucial for achieving the sustained burning plasma conditions necessary to realize fusion energy. For stellarator reactors, one proposed strategy for avoiding destructive instabilities is to operate at high field but low(er) plasma pressure. In this work, we investigate the accessibility of such a reactor-relevant low-beta regime in a reactor-scale quasi-axisymmetric stellarator using state-of-the-art high-fidelity macro- and microscopic simulation tools. We consider a configuration with a flattened core pressure profile and favorable properties from the macroscopic and neoclassical perspectives. By contrast, linear and nonlinear calculations with the GENE code show an abrupt transition to a regime of highly deleterious transport at low (local) plasma beta due to subdominant kinetic ballooning modes (KBMs). We describe the characterization of this transport regime as well as the confinement transition and stability boundaries. These observations contrast with previous analysis of quasi-symmetric stellarators which showed robustness against KBMs up to the magnetohydrodynamic (MHD) stability limit. Finally, we discuss the implications broadly for stellarator optimization and highlight the impact on quasi-symmetric stellarator design strategies.
Characterization: 1.0
Comments: