Ultrashort Laser-Induced Nuclear Reactions: Initiating Decay of Helium Nuclei and Subsequent Fusion Reactions.

We present a novel method to construct particle accelerators targeting light atoms and nuclei using high-power femtosecond laser pulses. Initially, we confine light atoms within the laser pulse envelope due to longitudinal polarization forces, allowing them to acquire kinetic energies of several GeV. Subsequently, an external electric field separates the nuclei at the cathode, concentrating helium nuclei in a small area. The kinetic energy of the 1.88 GeV impacts, exceeding the α particle binding energy (28 MeV) by 2 orders of magnitude, induces powerful γ radiation and neutron emission from decay processes. This experiment marks a demonstration of a laser-induced decay method for helium nuclei for the first time. Moreover, helium isotopes or deuterium nuclei trapped on the cathode show significantly reduced Coulomb repulsion, enabling subsequent nuclear fusion reactions and substantial nuclear energy release.