Analysis of the Angular Distribution of Emission of Neutrons Generated with the Ponderomotive Mechanism of Ion Heating by High-Power Short Laser Pulse Acting on a (CD2)n Target

Experiments on the angular distribution of DD neutrons generated in nuclear reactions upon irradiation of a (CD2)n target have been performed in the “Neodymium” laser facility. Apart from the main pulse, prepulses were observed in the experiment. Measurements have shown that neutrons have an isotropic angular distribution. Experimental results have been analyzed using hydrodynamic calculations accounting for the ponderomotive force. The ion heating mechanism in a shock wave emerging under the action of the ponderomotive pressure of the main pulse in the supercritical region of the plasma has been considered. It is shown that neutrons are generated mainly in the supercritical plasma heated by the ion heat wave. The time of plasma cooling due to hydrodynamic spreading turns out to be much longer than the isotropization time of the ion velocity distribution function due to Coulomb collisions. In these conditions, the neutron angular distribution must be isotropic.