Oxford Centre for High Energy Density Science (OxCHEDS)

Abstract:

WP10 is one of the working packages of the HiPER project and it has the goal of addressing, in a systematic and programmatic way, some of the key experimental uncertainties on the way towards fast ignition (and shock ignition) in a perspective of risk reduction, so to contribute to the definition of the basic characteristics of the HiPER project. The paper describes the key points contained in the short term HiPER experimental road map, as well as the results of two first experiments performed in "HiPER dedicated time slots" in European Laser Facilities. © 2010 American Institute of Physics.

Abstract:

In situ x-ray diffraction has been used to measure the shear strain (and thus strength) of single crystal copper shocked to 100 GPa pressures at strain rates over two orders of magnitude higher than those achieved previously. For shocks in the [001] direction there is a significant associated shear strain, while shocks in the [111] direction give negligible shear strain. We infer, using molecular dynamics simulations and VISAR (standing for 'velocity interferometer system for any reflector') measurements, that the strength of the material increases dramatically (to approximately 1 GPa) for these extreme strain rates.

Abstract:

A method for generating non-uniformly spaced (chirped) trains of high-energy, high-contrast, femtosecond pulses is described and demonstrated. In this method a temporally stretched laser pulse is passed through an acousto-optic programmable dispersive filter (AOPDF), a birefringent plate, and a linear polarizer. It is demonstrated that linear and nonlinear variation of the pulse separation within the train may be controlled by changing respectively the third-and fourth-order dispersion introduced by the AOPDF. Programmable, non-uniform pulse trains of this type may find applications in quasi-phase matching high-harmonic generation. © 2010 IOP Publishing Ltd.

Abstract:

We present the progress made in developing 10PW OPCPA facility for the Vulcan laser to produce pulses with focused intensities >1023 Wcm-2. This power level will be delivered by generating pulses with >300J in 30fs. These pulses will be delivered to two target areas: in one target area they will be combined with the existing Vulcan Petawatt beamline and a new target area will be created for high intensity interactions. © 2010 Optical Society of America.

Abstract:

Heating of the target core for fast ignition by electron beams is investigated by two-dimensional collisional particle-in-cell simulations. It is found that the electron beams emitted from the core surface with the initial energy of 1.4MeV, 2.4MeV, and 4.2MeV can heat most efficiently the core with ρr = 0.75g/cm2, 1.5g/cm2, and 3g/cm2, respectively, when taking ρ 300g/cm3, where ρ and r are the mass density and radius of the core, respectively. © 2010 IOP Publishing Ltd.