Prof Peter Norreys FInstP;

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.

Abstract:

The interaction of high intensity laser pulses with plasmas is an efficient source of megaelectronvolt ions. Recent observations of the production of directional energetic ion 'beams' from the front and rear surfaces of thin foil targets upon irradiation by intense laser pulses have prompted a renewed interest into research in this area. In addition, other recent observations have shown that high energy ions can be observed from intense laser interaction with low density plasma as a result of ponderomotive shock acceleration. The source characteristics and acceleration mechanisms for these ions have been extensively investigated, and there have also been a number of proposed applications for these ion beams, such as for injectors into subsequent conventional acceleration stages, for medicine, for probing of dense plasmas and for inertial confinement fusion experiments. © 2005 IOP Publishing Ltd.