Nuclear astrophysics experiments using high-energy-density plasmas

Throughout the universe, nuclear reactions play a critical role in the dynamics of stars and the formation of the elements, through processes including big-bang nucleosynthesis (BBN), stellar nucleosynthesis (SN), and production of heavy elements in explosive scenarios such as supernovae and neutron-star mergers. Fusion reactions are the primary energy source of the stars, determining their physical properties and lifetime. In the universe these processes occur in a plasma environment that is fundamentally different from accelerators, where nuclear physics is typically studied. Laser facilities in the United States, notably NIF and Omega, can generate plasmas at extreme conditions that are comparable to many astrophysical systems, including the universe a few minutes after the big bang and the core of our sun, and can include neutron fluxes comparable to supernovae and neutron-star mergers, unlike any other laboratory source. Initial experiments, largely at Omega, have measured cross sections or product spectra for several light-ion fusion reactions including T+3He, 3He+3He, and T+T reactions, which are relevant to BBN, SN, and basic nuclear physics. A growing collaboration is actively working on expanding these measurements to lower energies or additional reactions. Additionally, our future vision is to use high-energy-density plasmas to study several exciting aspects of nucleosynthesis in the laboratory, including addressing the problem of electron screening in dense plasma environments and nuclear physics at intense neutron fluxes analogous to explosive astrophysical events.