Development of shock-dynamics study with synchrotron-based time-resolved X-ray diffraction using an Nd:glass laser system

The combination of high-power laser and synchrotron X-ray pulses allows us to observe material responses under shock compression and release states at the crystal structure on a nanosecond time scale. A higher-power Nd:glass laser system for laser shock experiments was installed as a shock driving source at the NW14A beamline of PF-AR, KEK, Japan. It had a maximum pulse energy of 16 J, a pulse duration of 12 ns and a flat-top intensity profile on the target position. The shock-induced deformation dynamics of polycrystalline aluminium was investigated using synchrotron-based time-resolved X-ray diffraction (XRD) under laser-induced shock. The shock pressure reached up to about 17 GPa with a strain rate of at least 4.6 × 107 s–1 and remained there for nanoseconds. The plastic deformation caused by the shock-wave loading led to crystallite fragmentation. The preferred orientation of the polycrystalline aluminium remained essentially unchanged during the shock compression and release processes in this strain rate. The newly established time-resolved XRD experimental system can provide useful information for understanding the complex dynamic compression and release behaviors.

High-power, Joule-class, temporally shaped multi-pass ring laser amplifier with two Nd:glass laser heads

A high-power, Joule-class, nanosecond temporally shaped multi-pass ring laser amplifier system with two neodymium-doped phosphate glass (Nd:glass) laser heads is demonstrated. The laser amplifier system consists of three parts: an all-fiber structure seeder, a diode-pumped Nd:glass regenerative amplifier and a multi-pass ring amplifier, where the thermally induced depolarization of two laser heads is studied experimentally and theoretically. Following the injection of a square pulse with the pulse energy of 0.9 mJ and pulse width of 6 ns, a 0.969-J high-energy laser pulse at 1 Hz was generated, which had the ability to change the waveform arbitrarily, based on the all-fiber structure front end. The experimental results show that the proposed laser system is promising to be adopted in the preamplifier of high-power laser facilities.