High energy density plasma experiments to study the T+T and ³He+³He six-nucleon systems at OMEGA and the NIF

Thermonuclear reaction rates and nuclear processes are explored traditionally in accelerator experiments, which are difficult to execute at conditions relevant to Stellar and Big Bang Nucleosynthesis. High-Energy-Density (HED) plasmas mimic astrophysical environments and can complement accelerator experiments. We describe HED experiments^1,2 to study the T+T reaction at the OMEGA laser, and the ³He+³He reaction at the National Ignition Facility (NIF). Neutron spectra from the T+T reaction at ion temperatures from 4 to 18 keV, corresponding to center-of-mass (c-m) energies from 16 to 50 keV, show the ⁵He ground state resonant peak at 8.6 MeV being stronger at the higher than at the lower energy.³ This indicates a reaction mechanism that must involve resonances and/or higher angular momenta than L=0. Preliminary ³He+³He reaction data at c-m energies from 60-120 keV also indicate that the underlying physics changes with c-m energy.

[1] M. Gatu Johnson et al., Phys. Plasmas 24, 041407 (2017).

[2] M. Gatu Johnson et al., Phys. Plasmas 25, 056303 (2018).

[3] M. Gatu Johnson et al., submitted to Phys. Rev. Lett. (2018).