2023/10/01 by Elizabeth J. Paul, Harry E. Mynick, H.E. Mynick +2 · 2 citations
Physics and Astronomy · #Magnetic confinement fusion research #Atomic and Subatomic Physics Research #Nuclear physics research studies
paper · pdf · doi:10.1017/s0022377823001095
Significant progress has been made in designing magnetic fields that provide excellent confinement of the guiding-centre trajectories of alpha particles using quasisymmetry (QS). Given the reduction in this transport channel, we assess the impact of resonant Alfvén eigenmodes (AEs) on the guiding-centre motion. The AE amplitudes are chosen to be consistent with experimental measurements and large-scale simulations. We evaluate the drift resonance condition, phase-space island width and island overlap criterion for quasisymmetric configurations. Kinetic Poincaré plots elucidate features of the transport, including stiff transport above a critical perturbation amplitude. Our analysis highlights key departures from the AE-driven transport in tokamaks, such as the avoidance of phase-space island overlap in quasihelical configurations and the enhanced transport due to wide phase-space islands in low magnetic shear configurations. In configurations that are closer to QS, with QS deviations δ B/B0 \lesssim 10-3 , the transport is primarily driven by the AE, while configurations that are further from QS, δ B/B0 ∼ 10-2 , experience significant transport due to the QS-breaking fields in addition to the AE.