Prof Peter Norreys FInstP;

Abstract:

The Vulcan Nd: glass laser at the Central Laser Facility is a Petawatt (1015 W) interaction facility available to the UK and international user community. The facility came online to users in 2002 and considerable experience has been gained operating the Vulcan facility in this mode. The facility is designed to deliver irradiance on target of 1021 W cm-2 for a wide-ranging experimental programme in fundamental physics and advanced applications. This includes the interaction of super-high-intensity light with matter, fast ignition fusion research, photon induced nuclear reactions, electron and ion acceleration by light waves and the exploration of the exotic world of plasma physics dominated by relativity.

Abstract:

The structure of the hot electron beams emitted in laser-solid target interactions was analyzed. It was observed that electron beams were emitted from the rear of thin solid targets irradiated by a high-intensity short-pulse laser. It was shown that the most important condition in which electron beam filamentation due to Weibel-like instabilities become a factor were situations where large regions of low-density plasma exist. The results suggest that Weibel-like instabilities might not be important for the fast-ignitor scheme.

Abstract:

Ion-acceleration processes were studied in ultraintense laser plasma interactions for normal incidence irradiation of solid targets. Neutron spectroscopy was used for the purpose of analysis. It was found that the ions are preferentially accelerated radially. Results show that the laser pedestal generates a 10 μm scale length in the coronal plasma with a 3 μm scale-length plasma near the critical density.

Abstract:

The use of a single-photon-counting x-ray charge-coupled device (CCD) camera as an x-ray spectrometer is a well-established technique in ultrashort-pulse laser experiments. In single-photon-counting mode, the pixel value of each readout pixel is proportional to the energy deposited from the incident x-ray photon. For photons below 100 keV, a significant fraction of the events deposits all the energy in a single pixel. A histogram of the pixel readout values gives a good approximation of the x-ray spectrum. This technique requires almost no alignment, but it is very sensitive to signal-to-background issues, especially in a high-energy petawatt environment. Shielding the direct line of sight to the target was not sufficient to obtain a high-quality spectrum, for the experiments reported here the CCD camera had to be shielded from all sides with up to 10 cm of lead. © 2004 American Institute of Physics.