Mechanisms of D-D fusion and associated neutron-producing reactions in PW laser interactions with carbon-deuterated targets

The mechanisms of the D(d,n) ³ He fusion reaction and its associated neutron-producing reactions in petawatt laser interactions with CD and CD ₂ targets have recently attracted attention. The mechanisms by which ions are accelerated, causing fusion and other nuclear reactions are also a subject of debate. It was assumed that the D(d,n) ³ He fusion reaction is the only source of neutrons through thermonuclear and/or beam fusion mechanisms with a background of photoneutrons. In addition, ions acceleration occurs at the target front surface and within the electrostatic sheath on the rear surface. Here, through in-depth analysis of experimental measurements and simulations using 3-D Monte Carlo code, it was shown that nuclear reactions occur between accelerated ions and target background ions. The ions are accelerated at the target surface, causing nuclear reactions as they pass through the target, thus eliminating the effect of the electrostatic sheath on the rear side. The relative contribution of each reaction was assessed in comparison with the fusion reaction. Deuteron-Carbon stripping reactions contribute to overall neutron production, with a much higher neutron yield than that of the fusion reaction. Other reactions such as photonuclear reactions, deuteron breakup, and deuteron electro-disintegration must be considered.