Fast particle transport induced by shear Alfvén waves in stellarators

Recent advances in stellarator equilibrium field optimization enabled quasi-symmetric [1,2] and quasi-isodynamic [3] equilibria with reactor-relevant fusion-born alpha particle confinement [4]. However, as is well known from previous tokamak studies, [5] full analysis of fast particle losses must account for transport induced by shear Alfvén waves (SAW). Recent studies [6,7] have shown that a single imposed SAW harmonic can cause significant transport of fusion-born alphas from the stellarator equilibria. However, for self-consistent analysis, SAW harmonics must correspond to equilibrium field and plasma profiles.

In this work, we study fast particle transport in QS stellarator with SAW described by ideal reduced MHD [8] and hybrid MHD-kinetic [9] models. We couple these models with SIMSOPT [10] guiding center tracking, and assess the alpha particle transport from SAW composed of multiple harmonics with radial mode structure consistent with the equilibrium.

[1] Landreman M, Paul E. PRL 2022

[2] Landreman M, et al. Phys. Plasmas 2022

[3] Goodman AG, et al. JPP 2023

[4] Bader A, et al. JPP 2019

[5] Mynick HE. PoF 1993

[6] Paul EJ, et al. A. JPP. 2023

[7] White RB, Duarte VN. PoP 2023

[8] Spong DA, et al. PoP 2010

[9] Spong DA, et al. PoF 1992

[10] Landreman M, et al. JOS 2021