The investigation of high intensity laser driven micro neutron sources for fusion materials research at high fluence

The application of fast pulse, high intensity lasers to drive low cost DT point neutron sources for fusion materials testing at high flux/fluence is investigated. At present, high power benchtop lasers with intensities of 1018 W/cm2 are routinely employed and systems capable of ³ 1021 W/cm2 are becoming available. These potentially offer sufficient energy density for efficient neutron production in DT targets with dimensions of around 100 mm. Two different target concepts are analysed - a hot ion, beam-target system and an exploding pusher target system - and neutron emission rates are evaluated as a function of laser and target conditions. Compared with conventional beam-target neutron sources with steady state liquid cooling, the driver energy here is removed by sacrificial vaporization of a small target spot. The resulting small source volumes offer the potential for a low cost, high flux source of 14 MeV neutrons at close coupled, micro ( £ 1 mm) test specimens. In particular, it is shown that a laser driven target with ~ 100 J/pulse at 100 Hz (i.e. ~ 10 kW average power) and laser irradiances in the range Il2 ~ 1017-1019 W mm2/cm2 could produce primary, uncollided neutron fluxes at the test specimen in the 1014-1015 n cm-2 s-2 range. While focusing on the laser-plasma interaction physics and resulting neutron production, the materials science required to validate computational damage models utilizing ³ 100 dpa irradiation of such specimens is also examined; this may provide a multiscale predictive capability for the behaviour of engineering scale components in fusion reactor applications.