Ultra high-speed x-ray imaging of laser-driven shock compression using synchrotron light

Abstract

IntroductionThe properties of materials are driven to extreme conditions under high pressures, the highest of which is generated by shock compression. First described by George Gabriel Stokes in 1851 [1], 'a shock is a travelling wave front across which a discontinuous, adiabatic jump in state variables takes place'. Investigations of materials under shock compression cast light on a broad range of phenomena that are not fully understood in the areas of high-energy-density physics, earth and planetary sciences, aerospace engineering, and materials science. The three main progenitors of shock compression can be considered as: explosion, impact, and plasma [2]. Respectively, the most popular platforms for shock wave generation in the AbstractA high-power, nanosecond pulsed laser impacting the surface of a material can generate an ablation plasma that drives a shock wave into it; while in situ x-ray imaging can provide a timeresolved probe of the shock-induced material behaviour on macroscopic length scales. Here, we report on an investigation into laser-driven shock compression of a polyurethane foam and a graphite rod by means of single-pulse synchrotron x-ray phase-contrast imaging with MHz frame rate. A 6 J, 10 ns pulsed laser was used to generate shock compression. Physical processes governing the laser-induced dynamic response such as elastic compression, compaction, pore collapse, fracture, and fragmentation have been imaged; and the advantage of exploiting the partial spatial coherence of a synchrotron source for studying low-density, carbon-based materials is emphasized. The successful combination of a high-energy laser and ultra high-speed x-ray imaging using synchrotron light demonstrates the potentiality of accessing complementary information from scientific studies of laser-driven shock compression.

Using X-ray tomoscopy to explore the dynamics of foaming metal

“…Systems such as rechargeable batteries 41 , solidifying alloys 15,34,42,43 or evolving metallic foams 35,44–46 are of special interest. Time-resolved radioscopy for very short exposure times (down to 100 ps per image) and 1 Mfps repetition rate is possible 47 , but acquisition is limited to very short periods, thus not allowing to follow longer processes continuously. Tomography naturally has been much slower than radioscopy but some proofs of concept on solid samples have shown that acquisition rates of 100 tps are feasible 48 .…”

X‐Ray Topography—More than Nice Pictures

“…[67,81,106] In combination with the actually achieved even higher speed of imaging, the real-time 3D diffraction imaging comes within reach. [66]…”

“…The real-time observation of faster events like fracture and crack propagation in materials close to the speed of sound (up to about 4000 m s −1 e. g. in glass) needs the time structure of a synchrotron light source, combined with ultrafast imaging techniques, originally pioneered at the Advanced Photon Source (Argonne National Laboratory, USA) by Luo et al [64] Mechanically induced cracks in glass could be depicted by the so-called single-bunch phase contrast imaging at ESRF by Rack et al, with a velocity of ≈11.7 m s −1 . [65] Olbinado et al [66] used laser shock experiments to follow the compression of different materials with a MHz image rate. In polyurethane foam two fronts Figure 1.…”

Use of synchrotron-based radiography to diagnose pulsed power driven wire explosion experiments

“…It was important that the pulsed power fired with repeatable timing relative to the x-rays, but also that it could be manually triggered by the user. The timing scheme used here is a modification of the system used by Olbinado et al 22 A clock signal that was synchronised with the x-ray pulses was generated by the ESRF in-house developed bunch clock delay unit. This clock signal was input into a digital input/output module that could be manually triggered using the beamline computer.…”