Simultaneous measurement of laser-induced shock wave and released particle velocities at Mbar pressure

Abstract

We show the feasibility of simultaneous measurement of shock velocity and released particle velocity after shock at Mbar pressure. The shock wave is driven by a laser pulse of 1.2 ps duration (full width at half maximum), with the intensity of ∼1014 W/cm2 at 785 nm, irradiating a 500-nm-thick aluminum foil. A chirped laser pulse split from the main pulse is applied to detect the shock breakout process at the rear surface of the target based on frequency domain interferometry. The mean shock velocity determination benefits from the precise synchronization (<100 fs resolution) of the shock pump and probe laser pulse, which is calculated from the time the shock takes to travel the 500-nm-thick aluminum. The released particle velocity determination takes advantage of the chirped pulse frequency domain interferometry. The two measured parameters are self-consistent.

Non-Distractive Testing by Nanosecond Nd: Yag Laser Technique as Alternative Method to Find Nano -ZnO/Al Properties

“…Shock wavelength is the distance between two points on the wave and the corresponding point in the second wave [31][32][33][34]. Figure 11 shows the shock wave length after applying shock pressure before and after depositing nanoparticles; a surface with a transparent layer provides an effective method to enhance laser-induced shock wave pressure in the material target with a magnitude of the same laser intensity.…”

“…Figure 13 assumes a shock intensity vs. Shock force of Al, (a) without n-ZnO, (b) n-ZnO dissolved in water, (c) n-ZnO dissolved in ethanol at different laser intensities, the shock force different in all Al conditions due to the different velocities in the target measurement in two methods [32], ii. The background transducer errors by the normalized method may be because when the ultrasonic frequency was low, the cavitation-bubble pulsation and mass-transfer effect were enhanced by increasing the ultrasonic frequency, leading to slight underprediction of shock pressures so the shock velocity.…”

“…This shows that the shock force has a semi-constant value along with laser intensity. At high frequencies with intensity, the time required for the rarefaction cycle is too short to grow a cavitation bubble to a sufficient size, which causes the ideal disruption of liquid [32]. The shock force of Al alone is lower than in other conditions because the test specimen surface roughness can affect as i. scattering causes loss of sensitivity because of the refraction at the upper surface and reflection at a back surface (back wall).…”

“…Where Vl is the longitudinal acoustic velocity and ρ0 is the material density. Hooke's law gives the relation between stress & strain, which states as [31,32]:…”

Real time NDE of laser shock processing with time-of-flight of laser induced plasma shock wave in air by acoustic emission sensor

“…Also, the sensor used in the patent is airborne, which is sensitive to the interference of the surrounding environment for its resonant frequency of 20 kHz, and it is replaced by PXR15 acoustic emission sensor with resonant frequency of 150 kHz. A lot of experimental methods have been developed to detect the time-of-flight of the shock wave in air [13][14][15], which are not suitable in the operate condition of laser shock processing for the shock wave caused by interaction of the workpiece, the absorption layer, the containment layer and the laser beam.…”