Deuteron-deuteron fusion in laser-driven counter-streaming collisionless plasmas

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, the fusion $d+d{\to }^3\mathrm{He}+n$ is studied in a Gamow-like window around 27 keV. The results give hints that astrophysical nuclear reaction yields can be modulated significantly by the self-generated electromagnetic fields and the collective motion of the plasma. This plasma-version minicollider may provide a novel tool for studies of astrophysics-interested nuclear reactions, as well as a useful tool to constrain the models of plasma colliding dynamic.

Figure 1

The experimental setup. Four laser beams were tuned to focus on the target at one side and another four on the opposite side. By using the probe laser and a Nomarski interferometer, the optical images of the plasmas were taken. Neutron signals were recorded by scintillation detectors at different distances.

Figure 2

Typical TOF spectra of neutron detectors. Data from the four liquid scintillation detectors at distances of 5.3 m, 1.8 m, 5.3 m, and 8.0 m, are shown in the lower panel. The expected arriving times of photons and neutrons (2.45 MeV) for each detector are indicated by dashed lines in the upper panel. They match well with the TOFs measured by detectors at different distances.

Figure 3

(a) A typical Nomarski interferogram of the plasma streams, and (b) the corresponding electron density distribution derived by Abel inversion approach.

Figure 4

The Gamow-window-like feature of the neutron yield contributed by deuterium ions with different c.m. energies. Three lines are shown in this chart: the number of the ions from the experimental data (the dotted green line), the ${}^2\mathrm{H}(d,n){}^3\mathrm{He}$ cross section (the dashed red line), and the calculated neutron yield (the solid blue line).