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David Neely

Bio: David Neely is an academic researcher from Rutherford Appleton Laboratory. The author has contributed to research in topics: Laser & Electron. The author has an hindex of 45, co-authored 256 publications receiving 7466 citations. Previous affiliations of David Neely include Imperial College London & University of Strathclyde.
Topics: Laser, Electron, Plasma, Proton, Beam (structure)


Papers
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Journal ArticleDOI
01 Oct 1995-Nature
TL;DR: In this article, the authors report observations of relativistic plasma waves driven to breaking point by the Raman forward-scattering instability induced by short, high-intensity laser pulses.
Abstract: ELECTRONS in a plasma undergo collective wave-like oscillations near the plasma frequency. These plasma waves can have a range of wavelengths and hence a range of phase velocities1. Of particular note are relativistic plasma waves2,3, for which the phase velocity approaches the speed of light; the longitudinal electric field associated with such waves can be extremely large, and can be used to accelerate electrons (either injected externally or supplied by the plasma) to high energies over very short distances2a¤-4. The maximum electric field, and hence maximum acceleration rate, that can be obtained in this way is determined by the maximum amplitude of oscillation that can be supported by the plasma5a¤-8. When this limit is reached, the plasma wave is said to a¤˜breaka¤™. Here we report observations of relativistic plasma waves driven to breaking point by the Raman forward-scattering instability9,10 induced by short, high-intensity laser pulses. The onset of wave-breaking is indicated by a sudden increase in both the number and maximum energy (up to 44 MeV) of accelerated plasma electrons, as well as by the loss of coherence of laser light scattered from the plasma wave.

705 citations

Journal ArticleDOI
TL;DR: In this paper, the authors provide a comprehensive update of the current status of ultra-high-power lasers and demonstrate how the technology has developed, and what technologies are to be deployed to get to these new regimes, and some critical issues facing their development.
Abstract: In the 2015 review paper 'Petawatt Class Lasers Worldwide' a comprehensive overview of the current status of highpower facilities of >200 TW was presented. This was largely based on facility specifications, with some description of their uses, for instance in fundamental ultra-high-intensity interactions, secondary source generation, and inertial confinement fusion (ICF). With the 2018 Nobel Prize in Physics being awarded to Professors Donna Strickland and Gerard Mourou for the development of the technique of chirped pulse amplification (CPA), which made these lasers possible, we celebrate by providing a comprehensive update of the current status of ultra-high-power lasers and demonstrate how the technology has developed. We are now in the era of multi-petawatt facilities coming online, with 100 PW lasers being proposed and even under construction. In addition to this there is a pull towards development of industrial and multidisciplinary applications, which demands much higher repetition rates, delivering high-average powers with higher efficiencies and the use of alternative wavelengths: mid-IR facilities. So apart from a comprehensive update of the current global status, we want to look at what technologies are to be deployed to get to these new regimes, and some of the critical issues facing their development.

559 citations

Journal ArticleDOI
TL;DR: The use of ultra-high intensity laser beams to achieve extreme material states in the laboratory has become almost routine with the development of the petawatt laser as mentioned in this paper, which has been constructed for specific research activities, including particle acceleration, inertial confinement fusion and radiation therapy.
Abstract: The use of ultra-high intensity laser beams to achieve extreme material states in the laboratory has become almost routine with the development of the petawatt laser. Petawatt class lasers have been constructed for specific research activities, including particle acceleration, inertial confinement fusion and radiation therapy, and for secondary source generation (x-rays, electrons, protons, neutrons and ions). They are also now routinely coupled, and synchronized, to other large scale facilities including megajoule scale lasers, ion and electron accelerators, x-ray sources and z-pinches. The authors of this paper have tried to compile a comprehensive overview of the current status of petawatt class lasers worldwide. The definition of ‘petawatt class’ in this context is a laser that delivers .

464 citations

Journal ArticleDOI
TL;DR: In this paper, the authors extend the energy and intensity range over which proton scaling is experimentally investigated, up to 400 J and 6×10^20 Wcm−2 respectively, and find a slower proton scale than previously predicted.
Abstract: The possibility of using high-power lasers to generate high-quality beams of energetic ions is attracting large global interest. The prospect of using laser-accelerated protons in medicine attracts particular interest, as these schemes may lead to compact and relatively low-cost sources. Among the challenges remaining before these sources can be used in medicine is to increase the numbers and energies of the ions accelerated. Here, we extend the energy and intensity range over which proton scaling is experimentally investigated, up to 400 J and 6×10^20 Wcm−2 respectively, and find a slower proton scaling than previously predicted. With the aid of plasma-expansion simulation tools, our results suggest the importance of time-dependent andmultidimensional effects in predicting the maximum proton energy in this ultrahigh-intensity regime. The implications of our new understanding of proton scaling for potential medical applications are discussed. (Less)

373 citations

Journal ArticleDOI
TL;DR: A hybrid acceleration scheme based on the relativistic induced transparency mechanism using linearly polarised laser interaction with foil targets is demonstrated and its future implication in using high power lasers is explored.
Abstract: The range of potential applications of compact laser-plasma ion sources motivates the development of new acceleration schemes to increase achievable ion energies and conversion efficiencies. Whilst the evolving nature of laser-plasma interactions can limit the effectiveness of individual acceleration mechanisms, it can also enable the development of hybrid schemes, allowing additional degrees of control on the properties of the resulting ion beam. Here we report on an experimental demonstration of efficient proton acceleration to energies exceeding 94 MeV via a hybrid scheme of radiation pressure-sheath acceleration in an ultrathin foil irradiated by a linearly polarised laser pulse. This occurs via a double-peaked electrostatic field structure, which, at an optimum foil thickness, is significantly enhanced by relativistic transparency and an associated jet of super-thermal electrons. The range of parameters over which this hybrid scenario occurs is discussed and implications for ion acceleration driven by next-generation, multi-petawatt laser facilities are explored.

328 citations


Cited by
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Journal Article
TL;DR: In this article, a fast Fourier transform method of topography and interferometry is proposed to discriminate between elevation and depression of the object or wave-front form, which has not been possible by the fringe-contour generation techniques.
Abstract: A fast-Fourier-transform method of topography and interferometry is proposed. By computer processing of a noncontour type of fringe pattern, automatic discrimination is achieved between elevation and depression of the object or wave-front form, which has not been possible by the fringe-contour-generation techniques. The method has advantages over moire topography and conventional fringe-contour interferometry in both accuracy and sensitivity. Unlike fringe-scanning techniques, the method is easy to apply because it uses no moving components.

3,742 citations

Journal ArticleDOI
TL;DR: In this article, the authors present the landmarks of the 30-odd-year evolution of ultrashort-pulse laser physics and technology culminating in the generation of intense few-cycle light pulses and discuss the impact of these pulses on high-field physics.
Abstract: The rise time of intense radiation determines the maximum field strength atoms can be exposed to before their polarizability dramatically drops due to the detachment of an outer electron. Recent progress in ultrafast optics has allowed the generation of ultraintense light pulses comprising merely a few field oscillation cycles. The arising intensity gradient allows electrons to survive in their bound atomic state up to external field strengths many times higher than the binding Coulomb field and gives rise to ionization rates comparable to the light frequency, resulting in a significant extension of the frontiers of nonlinear optics and (nonrelativistic) high-field physics. Implications include the generation of coherent harmonic radiation up to kiloelectronvolt photon energies and control of the atomic dipole moment on a subfemtosecond $(1{\mathrm{f}\mathrm{s}=10}^{\mathrm{\ensuremath{-}}15}\mathrm{}\mathrm{s})$ time scale. This review presents the landmarks of the 30-odd-year evolution of ultrashort-pulse laser physics and technology culminating in the generation of intense few-cycle light pulses and discusses the impact of these pulses on high-field physics. Particular emphasis is placed on high-order harmonic emission and single subfemtosecond extreme ultraviolet/x-ray pulse generation. These as well as other strong-field processes are governed directly by the electric-field evolution, and hence their full control requires access to the (absolute) phase of the light carrier. We shall discuss routes to its determination and control, which will, for the first time, allow access to the electromagnetic fields in light waves and control of high-field interactions with never-before-achieved precision.

2,547 citations

Journal ArticleDOI
30 Sep 2004-Nature
TL;DR: It is demonstrated that this randomization of electrons in phase space can be suppressed and that the quality of the electron beams can be dramatically enhanced.
Abstract: Particle accelerators are used in a wide variety of fields, ranging from medicine and biology to high-energy physics. The accelerating fields in conventional accelerators are limited to a few tens of MeV m(-1), owing to material breakdown at the walls of the structure. Thus, the production of energetic particle beams currently requires large-scale accelerators and expensive infrastructures. Laser-plasma accelerators have been proposed as a next generation of compact accelerators because of the huge electric fields they can sustain (>100 GeV m(-1)). However, it has been difficult to use them efficiently for applications because they have produced poor-quality particle beams with large energy spreads, owing to a randomization of electrons in phase space. Here we demonstrate that this randomization can be suppressed and that the quality of the electron beams can be dramatically enhanced. Within a length of 3 mm, the laser drives a plasma bubble that traps and accelerates plasma electrons. The resulting electron beam is extremely collimated and quasi-monoenergetic, with a high charge of 0.5 nC at 170 MeV.

1,854 citations