Publications associated with Laser Fusion and Extreme Field Science

Kinetic simulations of fusion ignition with hot-spot ablator mix

Physical Review E American Physical Society 100 (2019) 033206

J Sadler, Y Lu, B Spiers, M Mayr, A Savin, R Wang, R Aboushelbaya, K Glize, R Bingham, H Li, K Flippo, P Norreys

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 VlasovFokker-Planck simulations that resolve hot-spot self heating in the presence a localised 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 localised 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.

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