Oxford Centre for High Energy Density Science (OxCHEDS)

Abstract:

We report imaging of coherent acoustic phonons on the picosecond time scale within a single nanocrystal using an X-ray free-electron laser. Our results allow unprecedented comparison with predictive models and observation of the vibrational modes. © 2014 OSA.

Abstract:

We present Non-Equilibrium Molecular Dynamics (NEMD) simulations of shock wave compression along the [001] direction in monocrystalline Tantalum, including pre-existing defects which act as dislocation sources. We use a new Embedded Atom Model (EAM) potential and study the nucleation and evolution of dislocations as a function of shock pressure and loading rise time. We find that the flow stress and dislocation density behind the shock front depend on strain rate. We find excellent agreement with recent experimental results on strength and recovered microstructure, which goes from dislocations to a mixture of dislocations and twins, to twinning dominated response, as the shock pressure increases. © 2013 Elsevier B.V.

Abstract:

We report on the dependence of the spatial properties of high harmonic generation on the harmonic order. We present interesting features in the transverse spatial coherence which may be important for coherent imaging experiments © OSA 2014.

Abstract:

We report on the dependence of the spatial properties of high harmonic generation on the harmonic order. We present interesting features in the transverse spatial coherence which may be important for coherent imaging experiments.Research in Optical Sciences © OSA 2014.

Abstract:

We report on the generation of bright multi-keV betatron X-ray radiation using a GeV laser wakefield accelerator and investigate the use of these X-rays for various imaging applications. © 2014 Optical Society of America.