Prof Peter Norreys FInstP;

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:

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.

Abstract:

We have conducted experiments on both the Vulcan and Titan laser facilities to study hot electron generation and transport in the context of fast ignition. Cu wires attached to Al cones were used to investigate the effect on coupling efficiency of plasma surround and the pre-formed plasma inside the cone. We found that with thin cones 15% of laser energy is coupled to the 40μm diameter wire emulating a 40μm fast ignition spot. Thick cone walls, simulating plasma in fast ignition, reduce coupling by x4. An increase of pre-pulse level inside the cone by a factor of 50 reduces coupling by a factor of 3. © 2010 IOP Publishing Ltd.

Abstract:

Collimated transport of fast electron beam through solid density matter is one of the key issues behind the success of the fast ignition scheme by means of which the required amount of ignition energy can be delivered to the hot spot region of the compressed fuel. Here we report on a hot electron beam collimation scheme in solids by tactfully using the strong magnetic fields generated by an electrical resistivity gradient according to Faraday's law. This was accomplished by appropriately fabricating the targets in such a way that the electron beam is directed to flow in a metal which is embedded in a much lower resistivity and atomic number metal. Experimental results showed guided transport of hot electron beam over hundreds of microns length inside solid density plasma, which were obtained from two experiments examining the scheme for petawatt laser driven hot electron beam while employing various target configurations. © 2010 IOP Publishing Ltd.