High energy density plasma experiments to study the solar ³He+³He reaction at the NIF and OMEGA lasers

Thermonuclear reaction rates and nuclear processes are explored traditionally in accelerator experiments, which are difficult to execute at conditions relevant to Stellar Nucleosynthesis. High-Energy-Density (HED) plasmas mimic astrophysical environments and can complement accelerator experiments. We describe HED experiments[1,2,3] to study the ³He+³He reaction at the National Ignition Facility (NIF) and OMEGA lasers. Preliminary ³He+³He proton energy spectra measured at center-of-mass (c-m) energies from 60-165 keV indicate that the underlying physics change with c-m energy, with the ⁵Li ground state resonant peak appearing to decrease in relative importance at higher c-m energy. This is in contrast to measurements of the mirror T+T reaction at c-m energies from 16 to 50 keV, which show the ⁵He ground state resonant peak being stronger at higher than at lower energy.[4] Challenges with using this platform to determine the reaction rate will also be discussed.

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

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

[3] A. Zylstra et al., Phys. Rev. Lett. 119, 222701 (2017).

[4] M. Gatu Johnson et al., Phys. Rev. Lett. 121, 042501 (2018).