| High power laser loading can achieve high pressure, high strain rate in the material, which create a chance for studying on material properties of materials under extreme conditions(super high pressure, high strain rate) in the laboratory. Laser loading is very flexible, Tera-Pascal(TPa) pressures can be achieved by laser-driven shock waves and laser-driven ramp compression. Recently, laser-driven shocks have become a reliable tool for obtaining high pressure equation of state. Laser ramp compression is the only tool that will allow scientists to examine the interior structure of exoplanets—planet in other solar systems—that are similar but larger than earth.The work of this thesis is carried out on the "Shenguang-Ⅱ" high power laser facility. The thesis can be divided into two major parts:In the first part, a high spacial(7um) and temperal(20ps) resolution velocity interferometer system for any reflector(VISAR) is introduced; In the second part, physical experiments(including basic physical problems in shock wave experiments and laser-driven ramp compression experiment) are introduced using VISAR as the main diagnostic equipment.A high spacial and temperal resolution velocity interferometer system for any reflector(VISAR) is implemented at "Shenguang-II" laser facility. The instrument measures shock breakout times at temporal resolutions as low as20ps, and spatial resolution-7um. For velocity measurements the detection limit is <0. lkm/s, and velocities of interface, free surfaces, and shock fronts traveling through transparent media can be measured with accuracies-2%over the range from5km/s to greater than50km/s. All technical indexes reach to international advanced level. Many creative work were performed during establishing the system:1. A novel polarization optical probe transmission system was designed and established, which significantly improves the energy utilization efficiency of the probe laser and solves the "ghost image" of non-target light. Meanwhile, the probe laser is continuous adjustable and meets the demand on laser energy of different experiments;2. The probe laser beam was spatial smoothed to uniform illumination, which improves the contrast of interference and the overall signal quality;3. A combining of microscope and image relay system is designed and developed. The image system has the features of high spatial resolution and flexible adjustment in long distance transmission;4. An interference image data processing software was developed, which can achieve real-time processing of experimental data and images.Physical experiments carried out using VISAR as the main diagnostic system, including shock timing experiment, preheat study, shock hugoniot measurement in transparent material et al. Shock timing experiment is an important content in inertial confine fusion research. We performed shock timing experiments in polystyrene and quartz. Experiments results of shock wave propagation, chase and coalescence were obtained; Preheat issue is an important content in laser-driven shock wave experiment. Preheat issue in laser-direct-driven shock experiment is studied in detail. The experimental results can direct impedance-match target design.The experiments which are frontier and having a good applied prospect are performed using high power laser as a driving source. They are laser-driven ramp compression and spallation experiments in high strain rates. Laser-driven ramp compression experiments can achieve high states of compression while simultaneously keeping the target material relatively cool so scientist can examine the material under high pressures. Laser-direct-driven ramp compression experiments are performed. Ramp compression formed using a kind of shaped laser pulse is reported scarcely. We investigated laser-direct-driven ramp compression using shaped pulses with different width pulses. We established the diagnostic and data processing ability for ramping compression experiment. |
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