Professor Justin Wark

Abstract:

Calculations of the patterns of x-ray diffraction from shocked crystals derived from the results of non-equilibrium molecular dynamics (NEMD) simulations are presented. The atomic coordinates predicted from the NEMD simulations combined with atomic form factors are used to generate a discrete distribution of electron density. A fast Fourier transform (FFT) of this distribution provides an image of the crystal in reciprocal space, which can be further processed to produce quantitative simulated data for direct comparison with experiments that employ picosecond x-ray diffraction from laser-irradiated crystalline targets. © 2008 IOP Publishing Ltd.

Abstract:

Recent progress in Laser Plasma Accelerators has demonstrated the possibility of generating GeV electron bunches with very interesting beam qualities. It is now conceivable that the further development of such devices could generate beams with emittance, energy spread and peak current suitable for FEL operation in the XUV range with relatively short undulator trains. In this context the OPALS project aims at the construction of a XUV radiation source, driven by a Laser Plasma Accelerator, capable of generating ultrashort fs XUV pulses. Such a source is small enough to be hosted in an academic or industrial institution and could therefore have a major impact on time-resolved science.

Abstract:

We present an analysis of the directionally dependent x-ray structure factors (and, hence, intensities) predicted by nonequilibrium molecular dynamics simulations of statically compressed and shocked single crystals of copper, and comment on the feasibility of using experimentally measured intensities to infer temperature information. We further consider the behavior of the diffracted intensity from isentropically compressed samples. © 2008 The American Physical Society.