Prof Peter Norreys FInstP;

Abstract:

In recent fast ignitor research, neutron measurements have become increasingly important not only to understand the ultraintense laser-plasma interaction physics associated with ion acceleration and energy transport processes in dense plasmas but also the characterization of the plasma temperature in integrated experiments, as summarized in this paper. New technologies that are relevant to the next-generation integrated fast ignition experiments are also reviewed. These will become increasingly important in the next few years as second-generation multikilojoule petawatt facilities come online and the detection environment becomes increasingly hostile, particularly if, as anticipated, the generated neutron fluxes begin to approach energy breakeven conditions.

Abstract:

We report the observation of monoenergetic electron beams (dE/E < 5%) produced by the interaction of a 12TW, 40fs laser pulse with underdense plasma, in contrast to all previous experiments, which produced energy spreads ~100%. © 2005 Optical Society of America.

Abstract:

The effect of focusing conditions in laser wakefield acceleration is studied. Short focal length geometries produce large dark currents while longer focal lengths produce narrow energy spread beams. © 2006 Optical Societ of America.

Abstract:

A possible new mechanism for anomalous ion heating in ultra-intense laser plasmas is considered here. This mechanism is based on the excitation of an electron two-stream instability that is driven by the fast electron beam and resonantly decays into ion-acoustic waves. These low frequency waves are then strongly damped by the ion collisions in the dense plasma. The model gives a simple explanation for the preferential heating of the bulk ion population observed in recent laser experiments in the petawatt (PW) regime. © 2005 IOP Publishing Ltd.