Line-imaging velocimeter for shock diagnostics at the OMEGA laser facility

Abstract

A line-imaging velocity interferometer has been implemented at the OMEGA laser facility of the Laboratory for Laser Energetics, University of Rochester. This instrument is the primary diagnostic for a variety of experiments involving laser-driven shock-wave propagation, including high-pressure equation of state experiments, materials characterization experiments, shock characterization for Rayleigh–Taylor experiments, and shock timing experiments for inertial confinement fusion research. Using a laser probe beam to illuminate a target, the instrument measures shock breakout times at temporal resolutions as low as $\text{20\hspace{0.5em}}\mathrm{ps}$ , and spatial resolution $\text{∼4\hspace{0.5em}μ}\mathrm{m}$ . For velocity measurements the detection limit is $\text{<0.1\hspace{0.5em}}\mathrm{km}/\mathrm{s}$ , and velocities of interfaces, free surfaces, and shock fronts traveling through transparent media can be measured with accuracies $\text{∼1\%}$ over the range from $\text{4\hspace{0.5em}}\mathrm{km}/\mathrm{s}$ to greater than $\text{50\hspace{0.5em}}\mathrm{km}/\mathrm{s}$ . Quantitative measurements of the optical reflectance of ionizing shock fronts can also be obtained simultaneously with the velocity measurements.