Accelerated deuterons in cluster-fusion experiments

Abstract

The collisional interaction of heavy-water clusters with TiD has been studied theoretically via three independent methods with the aim of estimating cluster-fusion yields. Particular attention was paid to multiple wide-angle-scattering processes between deuterons and heavy beam or target atoms. In order to achieve adequate statistics in molecular-dynamics simulations, the elastic-scattering cross section was enhanced by, roughly, increasing the deuteron charge at constant mass. Deuteron spectra were then determined by extrapolation to Z=1. The validity of the procedure was confirmed by comparison with simulations using unscaled interaction potentials. Monte Carlo simulations were also performed, using a code that incorporates target motion and allows for larger cluster and target size. Cross sections for double wide-angle-scattering events (Fermi shuttles) were computed directly. By all three methods we find clear evidence that deuterons are accelerated far beyond the limits imposed by single-scattering kinematics. We find exponential tails with slopes approximately inversely proportional to the incident energy per cluster atom. Estimated fusion yields increase very strongly with the energy per beam atom and lie 8 to 18 orders of magnitude below those reported experimentally.