Nova High‐Speed Jet Experiments

Abstract

We have conducted high-speed jet experiments using the Nova laser facility located at the Lawrence Livermore National Laboratory. The experiments make use of energy deposited in a Nova hohlraum to launch a strong shock down the axis of a cylindrical, millimeter-scale package containing a plastic/foam interface. The passage of the shock causes a hemispherical indentation at the interface to invert and form a plasma jet. The jet-tip velocity is approximately 60 km s~1, with a corresponding jet-tip Mach number of about 17. An X-ray backlighter foil and an electronic X-ray framing camera are used to radiograph the Ñow side-on. Vortical structures are observed, and the development of the jet over time is measured. An additional set of experiments was undertaken to elucidate these structures using a tracer material. Numerical simulations have been performed to provide additional insights into this Ñow and to permit examination of unmeasured quantities. The experiments include aspects of observed astrophysical jet phenomena, which could prove useful for benchmarking codes. Subject headings : ISM : jets and outÑows È methods : laboratory È shock waves È X-rays : general