Oxford Centre for High Energy Density Science (OxCHEDS)

Abstract:

We have performed short-pulse x-ray scattering measurements on laser-driven shock-compressed plastic samples in the warm dense matter regime, providing instantaneous snapshots of the system evolution. Time-resolved and angularly resolved scattered spectra sensitive to the correlation effects in the plasma show the appearance of short-range order within a few interionic separations. Comparison with radiation-hydrodynamic simulations indicates that the shocked plastic is compressed with a temperature of a few electron volts. These results are important for the understanding of the thermodynamic behavior of strongly correlated matter for conditions relevant to both laboratory astrophysics and inertial confinement fusion research.

Abstract:

Experimental results showing hot electron penetration into Cu wires using Kα fluorescence imaging are presented. A 500 J, 1 ps laser was focused at f/3 into hollow aluminum cones joined at their tip to Cu wires of diameters from 10 to 40 μm. Comparison of the axially diminishing absolute intensity of Cu Kα with modeling shows that the penetration of the electrons is consistent with one dimensional Ohmic potential limited transport. The laser coupling efficiency to electron energy within the wire is shown to be proportional to the cross sectional area of the wire, reaching 15% for 40 μm wires. Further, we find the hot electron temperature within the wire to be about 750 keV. The relevance of these data to cone coupled fast ignition is discussed. © 2009 American Institute of Physics.