Continuum Kinetic Modeling of Fusion Reactions and Elastic Scattering in ICF Plasmas

Experimental evidence suggests that kinetic effects might influence macroscopic performance parameters in inertial confinement fusion (ICF), including fusion yield [Hartouni et al., 2022]. Collisional relaxation of energetic alpha particles drives ion heating, but the details of this process are not resolved by hydrodynamic models. We present a multi-species kinetic model that includes fusion reactions and Coulomb collisions, capturing fusion heating, thermalization, and their effect on reactivity. Starting with a single-species deuterium plasma at fusion conditions, we solve Boltzmann and Landau collision operators using a fast Fourier spectral method [Jaiswal et al., 2019; Pareschi et al., 2000]. When the initial condition includes a suprathermal component, the fusion rate increases, leading to fusion and collisional timescales that are less separated than in the purely thermal case. Although thermalization still dominates early evolution, the reduced timescale separation suggests that a sustained population of energetic particles, such as from alpha heating, may inhibit full thermalization and preserve non-Maxwellian features—highlighting the significance of kinetic effects in hotspot fusion dynamics and their potential impact on the physics of all burning plasmas.