Explosion of a hydrogen ice sphere due to a pulsed fast neutron source

Abstract

Using a modified Lax-Wendroff numerical technique, the computer calculations of a hydrogen ice sphere exploding due to an energy deposition by slowed-down fast neutrons radiating from a strong point source are presented. Due to the large energy drop at each collision, the slowing-down process is treated by the approximate method, taking into account only the first three collisions. Calculations include the formation of a shock wave in the air outside the expanding hydrogen sphere. Because of the very large neutron energy and high source intensity, the binding and ionization energy of the hydrogen ice is neglected and is treated as a gas with a specific heat ratio of γ = 3. The neutron source in the numerical example corresponds to the explosion of the d- t micro-bomb of a diameter of about 1.5 mm. Calculations indicate that in order to recover most of the 14 MeV neutron energy, the radius of the hydrogen ice sphere should be of the order of 20 cm.