  In this Article, we study the hydrodynamics and burn of the thermonuclear
fuel in inertial confinement fusion pellets at the ion kinetic level. The
analysis is based on a two-velocity-scale Vlasov-Fokker-Planck kinetic model
that is specially tailored to treat fusion products (suprathermal
{\alpha}-particles) in a self-consistent manner with the thermal bulk. The
model assumes spherical symmetry in configuration space and axial symmetry in
velocity space around the mean flow velocity. Compared to fluid simulations
where a multi-group diffusion scheme is applied to model {\alpha} transport,
the full ion-kinetic approach reveals significant non-local effects on the
transport of energetic $\alpha$-particles. This has a direct impact on
hydrodynamic spatial profiles during combustion: the hot spot reactivity is
reduced, while the inner dense fuel layers are preheated by the escaping
{\alpha}-suprathermal particles, which are transported farther out of the hot
spot. We show how the kinetic transport enhancement of fusion products leads to
a significant reduction of the fusion yield.
