Deuterons and neutrons from cryogenic deuterium ribbons at Vulcan Petawatt

The sustained interest in laser-driven neutron sources comes from their compactness and affordability while opening the possibilities for a wide range of applications, potentially complementing the research carried out at large-scale spallation facilities. An experiment was carried out at the Vulcan Petawatt facility (CLF, UK) to generate bright, ultra-short neutron bursts employing cryogenic ribbons of solid deuterium. Cryogenic targets can in principle produce single species, debris-free ion beams suitable for a wide range of applications. Deuterium ions up to 25 MeV/nucleon were detected in the forward direction, correspondingly with high energy neutrons in high fluxes being produced. Due to the low density of the target (∼200 mg/cc) and the significant radiation pressure at the delivered laser intensities (5 × 10¹⁹ − 5 × 10²⁰ W/cm²), considerable compression of the deuterium plasma at the front surface is expected and accelerating bulk deuterium by the hole-boring mechanism. The neutrons are subsequently produced by the d(d,n)³He fusion reaction in the target bulk driven by ions produced by the hole-boring front. Preliminary particle-in-cell simulations support the experimental results to explain the underlying physics involving ps-class lasers at linear polarisation.