Shock Compression Spectroscopy Under a Microscope

Abstract

In this paper, I will describe recent progress in developing a tabletop apparatus for shock compression spectroscopy based on laser-driven flyer plates synchronized with high-speed lasers and optical and infrared detectors. The primary focus of the paper is technique development, although examples of applications are also provided. The flyer plates can be launched up to 6 km/s, but they are tiny, typically 0.5 mm in diameter and 50 μm thick, so the main limitations of this technique are the short duration of the shock, typically <15 ns, and the small sample size needed. The flyer launch and impact, monitored by photon Doppler velocimetry (PDV) and ultrafast strobe photography, show the flyers make exceptionally reproducible impacts with minimal tilt. Using fabricated shock target arrays containing 50–200 individual samples, hundreds of experiments can be conducted every day. Examples are presented involving time-resolved spectroscopy of quantum dot photoemission to measure compressional strain at high speed, time-resolved optical pyrometry to study shock initiation of plastic-bonded explosives and liquid explosives, and ultrafast spectroscopy to measure molecular photophysics under extreme conditions.