Description
Previous studies on the interaction between helium (He) ions and the drift wave–zonal flow (DW–ZF) system have typically adopted simplified representations, such as treating DW-driven transport as a local sink with fixed turbulence intensity [1] or considering He dilution effects with a non-evolving He profile [2]. In contrast, this work develops a self-consistent one-dimensional (1D) spatiotemporal model that captures the full bidirectional coupling between He ions and the DW–ZF system [3]. The model integrates three key physical components: (1) mutual interactions wherein He dilution modulates DW–ZF dynamics while DW-driven transport concurrently reshapes the He dilution profile; (2) explicit inclusion of dilution effects on both the real frequency and linear growth rate of DW; and (3) a turbulence spreading term in the DW evolution equation. Numerical results demonstrate that, compared to cases with fixed dilution profile and constant linear growth rate, the self-consistent evolution of He dilution and the dilution-modified growth rate leads to a reduced saturated dilution factor—particularly in the low-energy He ash population—along with increased DW energy and a reduced, or even reversed, radial profile of ZF energy. These findings suggest that He ash removal may be more achievable than previously estimated, although the enhancement in DW energy indicates that confinement improvement may be less optimistic than predictions based on fixed dilution assumptions. Analytical expressions for the saturated dilution factor, DW energy, and ZF energy derived under a local approximation qualitatively support the 1D numerical results. Overall, this work underscores the necessity of self-consistent modeling for reliably assessing He ash accumulation and confinement performance in future burning plasmas.
Key words: burning plasmas, 1D coupled model, helium ions
References
[1] M. Kotschenreuther, X. Liu, D. R. Hatch, et al. Nuclear Fusion, 2019, 59:096001
[2] M. T. Curie, D.R. Hatch, M. Halfmoon, et al. Nuclear Fusion, 2022, 62:126061
[3] A. Zocco, N. F. Loureiro, D. Dickinson, et al. Plasma Physics and Controlled Fusion, 2015, 57:065008
[4] J. W. Connor, R. J. Hastie, A. Zocco. Plasma Physics and Controlled Fusion, 2012, 54:035003