Generation of thermonuclear neutrons by laser action on a conical target

Experiments were performed on laser-beam compression of a deuterium-filled target consisting of conical cavities pressed into lead and closed with a lavsan polyester shell 5 microns thick and radius of curvature of 1.7 mm, the same as the dimension of the cone generator. The cone apex angle was 53 deg. The radiation was focused by a lens with f = 30 cm. The largest neutron yield of about 26,000 neutrons was recorded when laser radiation of energy 70 J and duration 25 nsec was focused on a target at 1 atm. An estimate shows that 8-14% of the laser radiation energy should be converted into energy of the compressed plasma. Shortening the laser pulse duration to 5 nsec while decreasing total energy to 30 J led to nearly complete vanishing of neutrons.