An experiment to study impact of non-Maxwellian ion velocity distributions in ICF-relevant conditions*

The long-standing question about impact of non-thermal ions on the fusion yield in inertial confinement fusion (ICF) implosions has recently been re-ignited with unexplained observations of apparent suprathermal signatures in the fusion product spectra from burning plasmas [1], and unexpected DD-to-D³He yield ratios from stellar-nucleosynthesis-relevant ICF implosion experiments [2]. To address this question, a new experimental platform is being developed at OMEGA with two opposing laser-driven CD foils surrounding a D₂ gas jet, in a planar, diagnostically accessible mock-up of a spherical ICF implosion. Hydrodynamic FLASH simulations show that ICF-relevant temperatures, densities and ion mean-free paths can be achieved with this setup, while kinetic iFP simulations suggest that highly non-Maxwellian ion velocity distributions can be produced. Thomson scattering and neutron spectrometry are used to directly and indirectly diagnose the ion velocity distributions. This poster discusses the initial results from these diagnostics as well as supporting data from the first experiments on this platform.

[1] Hartouni et al., “Evidence for suprathermal ion distribution in burning plasmas”, Nat. Phys. (2022).

[2] Kabadi, MIT PhD thesis (2022).