Ejecta from periodical grooves in tin foils under laser-driven shock loading

Velocity and mass density of the ejecta produced from sinusoidal grooves in laser shock-loaded tin

“…Finally, at a controlled delay time after the ns-drive, a 1.5 ps-duration laser probe of about 10 J was shot to the tip of a freestanding copper wire of 20 µm-diameter set about 1 cm below the grooved pattern. Subsequent emission of a ps-duration X-ray pulse, mainly K-shell radiation (at 8 keV for copper), allows ultra-short in-situ radiography of the ejecta [17,22,23] along the third (vertical) direction, normal to the shadowgraphy axis (Figure 2), using a distant image plate shielded with a 15 µm-thick aluminum foil. The spatial resolution was evaluated at about 20 µm from a static radiograph of a metal grid set at the sample position [22].…”

“…Subsequent emission of a ps-duration X-ray pulse, mainly K-shell radiation (at 8 keV for copper), allows ultra-short in-situ radiography of the ejecta [17,22,23] along the third (vertical) direction, normal to the shadowgraphy axis (Figure 2), using a distant image plate shielded with a 15 µm-thick aluminum foil. The spatial resolution was evaluated at about 20 µm from a static radiograph of a metal grid set at the sample position [22]. On-shot calibration of the X-ray signal was obtained from tin step wedges of controlled thicknesses inserted in front of the image plate, providing a direct correlation between the photo-stimulated luminescence recorded on the image plate and areal mass density.…”

“…For a few years, we have explored how laser-driven shocks can provide some valuable, complementary insights into ejecta physics under pulsed pressure loads of high amplitude (some tens of GPa) and very short duration (a few ns). Our results include measurements of jet velocities using both optical shadowgraphy and Photonic Doppler Velocimetry (PDV) [15][16][17], post-recovery evidence of the jetting process combined with spall fracture [15,17,18], attempts to estimate ejecta size distributions using fast shadowgraphy [16,19,20] or fragment recovery [21], and ultra-fast laser-based X-ray radiography of the jets [17,22,23]. The latter technique was used to evaluate mass ejection from single triangular grooves of controlled depths and angles [17].…”