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Title: Experimental study of radiative shocks in noble gases on the Orion laser and the MAGPIE pulsed-power facility
Author: Clayson, Thomas
ISNI:       0000 0004 7427 7758
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2018
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This Thesis introduces two novel experimental configurations for studying radiative shocks with the aim of improving our understanding of the physics involved, which is relevant to laboratory astrophysics, inertial confinement fusion and for benchmarking numerical simulations. Experiments on the Orion laser facility used lasers with an intensity of 5x10^14 W/cm^2 to drive counter-propagating shocks, with a velocity of 60 km/s, into a gas-fill (of Neon, Argon, Krypton or Xenon) with an initial mass density of 0.5 to 1.6 mg/cm^3. These experiments simultaneously study both the post-shock material and radiative precursor for the first time, with a combination of X-ray backlighting, self-emission streaked imaging and laser interferometry. Experiments with Neon gas-fills allowed for post-shock compression measurements, x23, and the counter-propagating shock configuration allowed reverse shocks to be studied. In addition, large gas-cells allowed for shocks to evolve in three dimensions, resulting in the formation of post-shock instabilities which will be the subject of future work. Experiments on the MAGPIE generator introduce the 'inverse liner z-pinch', building upon previous experiments on imploding liners where diagnostic access was limited and radiative effects occurred on spatial scales larger than the experiment. A 1 MA current pulse was passed through a liner embedded in a gas-fill (of Neon, Argon, Krypton or Xenon), with an initial mass density of 0.04 mg/cm^3, and returned through a central post. This launched a cylindrically expanding radiative shock which propagated at 10 km/s. Experiments were diagnosed with a combination of self-emission imaging, laser interferometry and optical emission spectroscopy. Shocks were able to propagate for several centimetres, allowing the ionization in the radiative precursor to be measured, which was not possible in previous experiments. Future work will use this platform to study radiative shocks with perturbations by introducing well characterised grooves on the surface of the liner.
Supervisor: Suzuki-Vidal, Francisco ; Lebedev, Sergey Sponsor: Engineering and Physical Sciences Research Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral