# Kinetic simulations of fusion ignition with hot-spot ablator mix

## TL;DR

This study uses kinetic simulations to analyze how localized ablator mix impacts hot-spot self-heating and fusion performance in inertial confinement fusion, revealing effects on cooling, reactivity, and neutron spectra.

## Contribution

It introduces detailed ion Vlasov-Fokker-Planck simulations to explore localized ablator mix effects on fusion ignition, highlighting kinetic and radiative impacts.

## Key findings

- Localized mix cools and contracts, increasing radiative losses.
- Mix reduces fusion reactivity by absorbing fast ions.
- Neutron spectra are broadened, affecting temperature inference.

## Abstract

Inertial confinement fusion fuel suffers increased X-ray radiation losses when carbon from the capsule ablator mixes into the hot-spot. Here we present one and two-dimensional ion Vlasov-Fokker-Planck simulations that resolve hot-spot self heating in the presence of a localized spike of carbon mix, totalling 1.9% of the hot-spot mass. The mix region cools and contracts over tens of picoseconds, increasing its alpha particle stopping power and radiative losses. This makes a localized mix region more severe than an equal amount of uniformly distributed mix. There is also a purely kinetic effect that reduces fusion reactivity by several percent, since faster ions in the tail of the distribution are absorbed by the mix region. Radiative cooling and contraction of the spike induces fluid motion, causing neutron spectrum broadening. This artificially increases the inferred experimental ion temperatures and gives line of sight variations.