First measurement of the 7Li(D, n) astrophysical S-factor in laser-induced full plasma

Abstract

Nuclear fusion reactions which produce energies and most of the elements in the Universe are the keys to driving the process of the Big Bang nucleosynthesis, as well as the evolution of stars. For fusions in real astrophysical conditions, it is crucial to directly measure them in the plasma environments. However, it is challenging to obtain reaction cross sections quantitatively because of the high instabilities of plasma. Here, an innovative self-calibration method is proposed to eliminate the large uncertainties caused by the plasma instabilities. And for the first time, it is applied to investigating the deuteron-lithium nuclear-fusion reaction 7Li(D,n)8Be in the plasma, which is related to the Big Bang lithium abundance puzzle. Further, the reaction's astrophysical S-factor in the Gamow window around 173 keV in the plasma is measured to be S=(24±8) MeV⋅barn, which demonstrates from an experimental point of view that the coulomb screening effect does not play an essential role in this 7Li consuming reaction related to the Big Bang lithium abundance puzzle. This self-calibration method for nuclear reactions in the plasma can also be applied to exploring other nuclear-fusion reactions, such as 7Li(p,α)4He and 6Li(p,α)3He, as well as providing a new probe for detecting plasma dynamics.

Keywords

• Nuclear fusion in plasma
• Laser driven nuclear physics
• Astrophysical S-factor
• Counter-streaming plasma collision