Speaker
Description
Future D–T burning plasmas generate energetic alpha particles that gradually evolve into thermalized helium ash. The resulting helium ions modify turbulence through dilution effects, while turbulence simultaneously regulates helium-ion transport. Understanding this mutual interaction is essential for predicting both confinement performance and helium-ash exhaust in future fusion reactors.
A self-consistent one-dimensional spatiotemporal model is developed to investigate the interactions between full-energy helium ions and a drift wave-zonal flow (DW–ZF) system. The model self-consistently evolves helium-ion dilution, drift-wave turbulence and zonal flows, while incorporating dilution effects on both the drift-wave frequency and growth rate. Unlike conventional approaches employing prescribed dilution profiles, the present framework captures the nonlinear feedback between helium ions and turbulence.
Numerical results show that the self-consistent evolution significantly reduces the saturated helium-ion dilution factor, particularly the contribution from lower-energy helium ash. Consequently, helium-ash removal becomes more achievable, while drift-wave turbulence is enhanced and zonal-flow energy is reduced. These findings suggest that the beneficial role of dilution in improving confinement may be overestimated in models employing fixed dilution profiles. Overall, this work highlights the importance of self-consistent helium-ion/turbulence evolution for reliably assessing burning-plasma performance.
Reference
Z. Mai, W. Guo* and L. Wang, Nuclear Fusion 66 (2026) 026004