  Nuclear fusion reactions are the most important processes in nature to power
stars and produce new elements, and lie at the center of the understanding of
nucleosynthesis in the universe. It is critically important to study the
reactions in full plasma environments that are close to true astrophysical
conditions. By using laser-driven counter-streaming collisionless plasmas, we
studied the fusion D$+$D$\rightarrow n +^3$He in a Gamow-like window around 27
keV. The results show that astrophysical nuclear reaction yield can be
modulated significantly by the self-generated electromagnetic fields and the
collective motion of the plasma. This plasma-version mini-collider may provide
a novel tool for studies of astrophysics-interested nuclear reactions in plasma
with tunable energies in earth-based laboratories.
