Enhancement to fusion reactivity in turbulent plasma

When fast ions travel through a plasma containing inhomogeneous background flows, their velocities vary with respect to the local fluid, enhancing the tail of the distribution function and producing higher fusion reactivity. This “shear flow reactivity enhancement effect” can be substantial because the long mean free path of ions near the Gamow peak allows them to cross large flow differentials even when thermal ions, which govern viscosity, are highly collisional [1]. Fusion reactivity can increase severalfold in turbulent plasma, where many rapidly swirling eddies moving relative to each other lead to regions of strong shear. This reactivity enhancement is quantified with analytical models and simulations, and simple formulas are provided to estimate the magnitude of the effect in models and hydrodynamic codes [2]. In inertial confinement fusion, turbulence driven on fine spatial scales inside a hot spot allows ignition at lower temperature and smaller hot-spot radius [3].

[1] H. Fetsch and N. J. Fisch, arXiv 10.48550/arXiv.2410.03590 (2024)

[2] H. Fetsch and N. J. Fisch, arXiv 10.48550/arXiv.2506.13711 (2025)

[3] H. Fetsch and N. J. Fisch, arXiv 10.48550/arXiv.2507.18917 (2025)