|Title:||Counter-propagating radiative shock experiments on the Orion laser and the formation of radiative precursors||Authors:||Clayson, T.
Lebedev, S. V.
Singh, R. L.
Gil, J. M.
Espinosa Vivas, Guadalupe
|UNESCO Clasification:||22 Física||Keywords:||Radiative shock
Counter propagating shocks
|Issue Date:||2017||Journal:||High Energy Density Physics||Abstract:||We present results from new experiments to study the dynamics of radiative shocks, reverse shocks and radiative precursors. Laser ablation of a solid piston by the Orion high-power laser at AWE Aldermaston UK was used to drive radiative shocks into a gas cell initially pressurised between 0.1 and 1.0 bar with different noble gases. Shocks propagated at 80 +/- 10 km/s and experienced strong radiative cooling resulting in post-shock compressions of x25 +/- 2. A combination of X-ray backlighting, optical self-emission streak imaging and interferometry (multi-frame and streak imaging) were used to simultaneously study both the shock front and the radiative precursor. These experiments present a new configuration to produce counter-propagating radiative shocks, allowing for the study of reverse shocks and providing a unique platform for numerical validation. In addition, the radiative shocks were able to expand freely into a large gas volume without being confined by the walls of the gas cell. This allows for 3-D effects of the shocks to be studied which, in principle, could lead to a more direct comparison to astrophysical phenomena. By maintaining a constant mass density between different gas fills the shocks evolved with similar hydrodynamics but the radiative precursor was found to extend significantly further in higher atomic number gases (similar to 4 times further in xenon than neon). Finally, 1-D and 2-D radiative-hydrodynamic simulations are presented showing good agreement with the experimental data.||URI:||http://hdl.handle.net/10553/35732||ISSN:||1574-1818||DOI:||10.1016/j.hedp.2017.03.002||Source:||High Energy Density Physics [ISSN 1574-1818], v. 23, p. 60-72|
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