Investigation of Direct Laser Impulses as surrogates for intense x-ray encounters

Direct Laser Impulse (DLI) is an experimental platform in which a high-power optical laser strikes a tamper material to emulate the compression wave generated by deposition of intense x-ray pulses in metal. This study presents analysis of DLI experiments on titanium alloys. Simple, flat titanium targets adhered to a tamper were subjected to a direct laser impulse on the Orion Laser at the UK’s Atomic Weapons Establishment. The motion of the rear surface of the target was measured with a PDI to determine characteristics of the resulting compression wave and the rigid motion of the sample. These data allow analysis of the wave speed, impulse, and dissipation, the laser ablation pressure, and the conversion of laser energy to mechanical energy. Supporting simulations aid in interpreting the conclusions from the data. The laser induced compression waves are compared to similar phenomena produced on the x-ray effects campaign on the NIF and to relevant flyer plate experiments. Conclusions and methods from this study will be important to a new DLI capability that is undergoing commissioning at the NIF.