Oxford Centre for High Energy Density Science (OxCHEDS)

Abstract:

The VULCAN [C. N. Danson et al., Opt. Commun. 103, 392 (1993)] laser at the UK Central Laser Facility is being used for laboratory-based simulations of collisionless shocks. By ensuring that key dimensionless parameters in the experiments have values similar to those of supernova remnants (SNRs), the hydrodynamics and magnetic field of the experiment are scaled to those of a SNR. This makes it possible to investigate experimentally the physics of collisionless magnetized shocks in such objects. The experiments are providing data against which to test current theory. Collisionless shock formation and the interaction of two counterpropagating colliding plasmas permeated by a strong magnetic field are discussed. © 2001 American Institute of Physics.

Abstract:

The generation of MeV electron and ion beams using lasers with intensities of up to 1020 W cm-2 is reported. Intense ion beams with high energies (up to 40 MeV and to 3 × 1012 protons >5 MeV) are observed. The properties of these particle beams were measured in considerable detail and the results are compared to current theoretical explanations for their generation. © 2001 American Institute of Physics.

Abstract:

Pump-probe time-resolved x-ray diffraction of allowed and nearly forbidden reflections in InSb is used to follow the propagation of a coherent acoustic pulse generated by ultrafast laser excitation. The surface and bulk components of the strain could be simultaneously measured due to the large x-ray penetration depth. Comparison of the experimental data with dynamical diffraction simulations suggests that the conventional model for impulsively generated strain underestimates the partitioning of energy into coherent modes.