Single-Shot Multi-Frame Imaging of Cylindrical Shock Waves in a Multi-Layered Assembly

Leora Dresselhaus-Cooper,Benjamin K Ofori-Okai,Arianna Gleason,Dmitro J Martynowych,Steven Kooi,Chris T Key,Keith A Nelson,Joshua E Gorfain,Suzanne J Ali

doi:10.1038/s41598-019-40037-3

Abstract

We demonstrate single-shot multi-frame imaging of quasi-2D cylindrically converging shock waves as they propagate through a multi-layer target sample assembly. We visualize the shock with sequences of up to 16 images, using a Fabry-Perot cavity to generate a pulse train that can be used in various imaging configurations. We employ multi-frame shadowgraph and dark-field imaging to measure the amplitude and phase of the light transmitted through the shocked target. Single-shot multi-frame imaging tracks geometric distortion and additional features in our images that were not previously resolvable in this experimental geometry. Analysis of our images, in combination with simulations, shows that the additional image features are formed by a coupled wave structure resulting from interface effects in our targets. This technique presents a new capability for tabletop imaging of shock waves that can be extended to experiments at large-scale facilities.

Highlights

The destructive and variable nature of shock waves places high importance on techniques that can provide time-dependent observations in a single experiment[1,2]
Www.nature.com/scientificreports the shock’s trajectory by assembling single-frame measurements with varied delays between the excitation and imaging pulses from different regions of the sample. While this technique proved informative for studying low-pressure, reproducible shock waves in samples that were essentially uniform spatially, challenges remained in characterizing the dynamics of events that differ from shot to shot, such as geometric instabilities near the center of convergence[13], fracture[14], and shock-induced decomposition of energetic materials[15]
Shadowgraph image signal comes from probe light refraction due to refractive-index changes in the material, in this case caused by density variations from the shock wave[5,17]

Summary

Introduction

The destructive and variable nature of shock waves places high importance on techniques that can provide time-dependent observations in a single experiment[1,2]. The shock’s trajectory by assembling single-frame measurements with varied delays between the excitation and imaging pulses from different regions of the sample While this technique proved informative for studying low-pressure, reproducible shock waves in samples that were essentially uniform spatially, challenges remained in characterizing the dynamics of events that differ from shot to shot, such as geometric instabilities near the center of convergence[13], fracture[14], and shock-induced decomposition of energetic materials[15]. To measure these and other phenomena whose details are not reproducible, we need to collect the entire image sequence in a single shock event. Single-shot multi-frame imaging has revealed important features that single-frame images could not discern about shock propagation in our multi-layer targets, including features such as geometric instability as well as coupled-wave effects at interfaces that have rarely been observed directly in any sample geometry

Methods

Results

Discussion

Conclusion