Alpha-particle confinement in an optimized stellarator with fusion reactor parameters

In this work, we present a detailed assessment of fusion-born alpha-particle confinement, their wall loads, and stability of Alfven eigenmodes driven by these energetic particles in an optimized stellarator designed to operate in deuterium-tritium fusion conditions.

We use the Monte-Carlo codes SIMPLE, ASCOT5, and KORC-T, we study the collisionless and collisional dynamics of alpha-particles in the core plasma, clearly identifying the population of alpha-particles lost in all analyzed conditions. Our simulations shows that peak power loads on the wall of this configuration are spatially localized, toroidally, and poloidaly in the vicinity of x-points of the magnetic island chain outside the plasma volume. We show how alpha-particle dynamics and geometry of the plasma work together to produce such localized power loads on the wall. These wall loads are observed to fall within manageable limits with existing technologies. Our stability assessment of Alfven eigenmodes using the STELLGAP and FAR3d codes shows the absence of unstable modes driven by alpha-particles in this configuration due to the relatively low alpha-particle beta at the envisioned operating scenario.