Simplified laser-driven flyer plates for shock compression science

Abstract

We describe a simplified system of laser-driven flyer plates for shock compression science and shock spectroscopy. We used commercially available one-box Nd:YAG lasers and beam homogenization solutions to create two launch systems, one based on a smaller (400 mJ) YAG laser and an inexpensive diffusive optic, and one based on a larger (2500 mJ) laser and a diffractive beam homogenizer. The flyer launch, flight, and impact processes were characterized by an 8 GHz fiberoptic photon Doppler velocimeter. We investigated effects of different substrates, adhesives, absorbers, ablative layers, and punching out disks from continuous foils versus fabricating individual foil disks, and found that a simple metal foil epoxied to a glass window was satisfactory in almost all cases. Our simplified system launched flyer plates with velocities up to 4.5 km s(-1) and kinetic energies up to 250 mJ that can drive sustained steady shocks for up to 25 ns. The factor that limits these velocities and energies is the laser fluence that can be transmitted through the glass substrate to the flyer surface without optical damage. Methods to increase this transmission are discussed. Reproducible flyer launches were demonstrated with velocity variations of 0.06% and impact time variations of 1 ns. The usefulness of this flyer plate system is demonstrated by Hugoniot equation of state measurements of a polymer film, emission spectroscopy of a dye embedded in the polymer, and impact initiation and emission spectroscopy of a reactive material consisting of nanoscopic fuel and oxidizer particles.

High-Speed Laser-Launched Flyer Impacts Studied with Ultrafast Photography and Velocimetry

“…The simplest method of laser flyer launching involves focusing a nanosecond high-energy laser pulse onto a sheet of metal foil [1,21], or onto a flyer plate optic consisting of a sheet of foil bonded to a transparent window [22]. The usual mechanism of flyer launch involves creating a metal plasma in a thin layer of the foil facing the laser [13,[23][24][25].…”

Shock compression dynamics under a microscope

“…Our simplified flyer system, characterized by extensive PDV studies, has been described in detail previously [1,2]. We have overcome most of the problems mentioned above using a commercial one-box Q-switched Nd:YAG laser (Quanta-Ray Pro 350-10), a diffractive beam homogenizer, a pulse stretcher [8], and a different launch mechanism [2].…”

“…We have also launched Cu and other metal foils, but Al is our workhorse. shows sample PDV traces for the launch of a 0.7 mm diameter x 50 m thick Al flyer onto a glass witness plate [1,2]. Figure 4a was computed using short-time Fourier transform [2,9].…”

“…Our laboratory has developed a tabletop laser miniflyer launcher [1,2] that can be used for a variety of studies in physical and chemical sciences. A microgram quantity of sample sits at the focus of a microscope objective that transmits the photon Doppler velocimeter (PDV) online flyer plate diagnostic to the sample and transmits and receives probe light from the shocked sample.…”

Laser shock ignition of porous silicon based nano-energetic films

“…14 Photon Doppler velocimetry (PDV) has emerged as a simple technique for measurement of U fs using relatively inexpensive off-the-shelf fibre optic components. 13,16,17 By using the optical interference of Doppler-shifted light that is reflected from the moving target surface, one can record U fs as a function of time.…”