A history of high-power laser research and development in the United Kingdom

The first demonstration of laser action in ruby was made in 1960 by T. H. Maiman of Hughes Research Laboratories, USA. Many laboratories worldwide began the search for lasers using different materials, operating at different wavelengths. In the UK, academia, industry and the central laboratories took up the challenge from the earliest days to develop these systems for a broad range of applications. This historical review looks at the contribution the UK has made to the advancement of the technology, the development of systems and components and their exploitation over the last 60 years

Ultra-High-Intensity Laser Propagation Through Underdense Plasma

International audiencePicosecond resolution shadowgraphy is a powerful tool for measurement of high-intensity laser propagation instabilities through underdense plasma. It is shown that as the plasma density increases, the laser beam is subject to severe filamentation instabilities—likely due to the effect of stimulated Raman side-scattering. At higher plasma densities, scattering and absorption are so severe that the propagation distance of the high intensity laser pulse is reduced

Proton acceleration and high energy density physics from laser foil interactions

Our team has provided the first observations of energetic ion beam production from the front and rear surfaces thin foil targets upon irradiation by an intense laser beam in the relativistic regime. We invented a new plasma diagnostic technique in which "layered" track detectors and dosimetry media were used to simultaneously record ion angular emission patterns as well as ion spectral information. These results have led to a large number of further experiments in which similar measurement techniques were used and in which protons have been measured up to 58 MeV. The source and acceleration mechanisms for these proton beams have been extensively investigated. There have also been a number of proposed applications for these ion beams, such as for injectors into subsequent conventional acceleration stages, for probing of dense plasmas and for inertial confinement fusion experiments. © 2005 IEEE

Electron Beam Production with an Ultra Short and Intense Laser Pulse: A New Tool for Scientists

International audienceBy focusing a 10 Hz, 30 TW, 30 fs laser beam onto a gas jet, it is now possible to produce an ultra short and high quality electron beam with a maximum energy of up to 200 MeV. The gas is instantaneously ionized by the laser electric field and transformed into plasma, in which accelerating electric fields of the order of 1 TV/m have been generated in the non-linear regime. Some applications of this attractive and compact electron source are presented

Measurements of forward scattered spectra from intense laser interactions in the forced laser wake-field regime

International audienceResults of an experiment using an ultra-short laser pulse to create plasma waves through the forced laser wake-field process are described. The transmitted optical spectra are shown to exhibit both red- and blue-shifting, likely due to self-phase modulation through the interaction between the laser pulse and a large amplitude plasma wave. Spectral side-bands shifted by multiples of the plasma frequency associated with the forward Raman instability (FRS) are absent, indicating that the plasma waves which are observed to accelerate electrons are likely not generated through the FRS process. One- and two-dimensional particle-in-cell simulations using similar parameters as the experiment are discussed

High intensity laser-plasma sources of ions-physics and future applications

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

Observation of Raman forward scattering and electron acceleration in the relativistic regime

International audienceRaman forward scattering (RFS) is observed in the interaction of a high intensity (>1018 W/cm2) short pulse (<1 ps) laser with an underdense plasma (ne~1019 cm -3). Electrons are trapped and accelerated up to 44 MeV by the high-amplitude plasma wave produced by RFS. The laser spectrum is strongly modulated by the interaction, showing sidebands at the plasma frequency. Furthermore, as the quiver velocity of the electrons in the high electric field of the laser beam becomes relativistic, various effects are observed which can be attributed to the variation of electron mass with laser intensit

Interaction of ultraintense laser pulses with an underdense, preformed plasma channel

International audienceWe report on experimental results regarding the propagation of ultraintense laser pulses in a preformed plasma channel. In this experiment, the long (4-mm) fully ionized plasma channel created by the amplified spontaneous emission (ASE) was measured by interferometry before and after the propagation of the short laser pulse. Forward spectra show a cascade of Raman satellites, which merge with one another when the laser power was increased up to critical power for relativistic self-focusing Pc. The number of filaments measured by interferometry increases when the laser power increases. High conversion efficiency (≈10%) of second harmonic generation was observed in the interactio