Oxford Centre for High Energy Density Science (OxCHEDS)

Abstract:

The effect of focusing conditions in laser wakefield acceleration is studied. Short focal length geometries produce large dark currents while longer focal lengths produce narrow energy spread beams. © 2006 Optical Societ of America.

Abstract:

We describe measurements characterizing the interaction of ultra-high intensity Petawatt laser pulses with solid targets. Experiments were performed on the Petawatt laser at RAL, and the Titan laser at LLNL. © 2006 Optical Society of America.

Abstract:

Recent published work has shown that the phase change of shock-compressed iron along the [001] direction does transform to the [hexagonal close-packed (hcp)] phase similar to the case for static measurements. This article provides an in-depth analysis of the experiment and nonequilibrium molecular dynamics simulations, using x-ray diffraction in both cases to study the crystal structure upon transition. Both simulation and experiment are consistent with a compression and shuffle mechanism responsible for the phase change from body-centered cubic to hcp. Also both show a polycrystalline structure upon the phase transition, due to the four degenerate directions in which the phase change can occur. © 2006 The American Physical Society.