The Vulcan Nd:glass laser at the Central Laser Facility (CLF) is a petawatt (1015 Watts) interaction facility, designed to deliver irradiance on target of 1021W.cm−2 for the UK and international user community. The facility came online to users in 2002 and considerable experience has been gained operating Vulcan in this mode. The facility delivers a wide-ranging experimental program in fundamental physics and advanced applications. This includes the interaction of ultrahigh 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. We report on the first year's operation of the facility and the highlights of the experimental campaigns.

The simple physical model of highly charged ion generation in plasma produced by laser irradiation with long pulse duration (>1 ns) and moderate intensities (<1015/λ2 W/cm2μm2) is presented. In the frame of a single theory, most of the experimental results on plasma diagnostics are described in total. It is shown that plasma temperatures, ion charge states, and ion velocities as well as angular distributions of highly charged ions can be explained with good accuracy by collisional absorption of laser energy, hydrodynamic acceleration of forming plasma, and three-body recombination through highly exited levels during plasma expansion into vacuum. The general scalings for plasma parameters are derived on the basis of the model proposed.

The first stage of the petawatt excimer laser project started at the P.N. Lebedev Physical Institute, implements a development of multiterawatt hybrid GARPUN-MTW laser facility for generation of ultra-high intensity subpicosecond ultraviolet (UV) laser pulses. Under this project, a multi-stage e-beam-pumped 100-J, 100-ns GARPUN KrF laser was upgraded with a femtosecond Ti:Sapphire front-end, to produce combined subpicosecond/nanosecond laser pulses with variable time delay. Attractive possibility to amplify simultaneously short and long pulses in the same large-scale KrF amplifiers is analyzed with regard to the fast-ignition, inertial confinement fusion problem. Detailed description of hybrid laser system is presented with synchronized KrF and Ti:Sapphire master oscillators. Based on gain and absorption measurements at GARPUN amplifier and numerical simulations with a quasi-stationary code, we are predicting that 1.6 J can be obtained in a short pulse at hybrid GARPUN-MTW Ti:Sapphire/KrF laser facility, combined with several tens of joules in nanosecond pulse. Amplified spontaneous emission, which is responsible for the pre-pulse formation on a target, was also investigated: its acceptable level can be provided by properly choosing staged gain or loading the amplifiers by quasi-steady laser radiation. Fluorescence and transient absorption spectra of Ar/Kr/F2 mixtures conventionally used in KrF amplifiers were recorded to find out the possibility for femtosecond pulse amplification at the broadband Kr2F (42Γ → 1,2 2Γ) transition, which benefits in 100 times higher saturation energy density than for KrF (B → X) transition.

This article presents results of theoretical and experimental studies on the production of ultrashort (a few RF cycles duration) microwave pulses of gigawatt peak powers based on superradiance from high-current electron beams. With the Cherenkov backward-wave–electron-beam interaction in a low-dispersion slow-wave structure, microwave pulses with a peak power greater than the peak power of the driving electron beam have been produced for the first time. In an experiment using the SINUS-150 compact high-current electron accelerator, with a 2.6-kA injected beam current and a 330-kV electron energy, microwave pulses of 1.2 GW peak power and ∼0.5 ns duration (FWHM) were generated in the X-band. Production of superradiance pulses in a repetitive regime (3500 Hz) in the Ka-band has been demonstrated using a compact hybrid SOS-modulator. The effect of spatial accumulation of microwave energy in extended slow-wave structures with substantially nonuniform coupling has been demonstrated. In an experiment using the SINUS-200 compact accelerator, X-band pulses of ∼3 GW peak power and 0.6–0.7 ns width (FWHM) were produced with a power conversion efficiency of 150–180% and an energy efficiency of ∼15%.

A “table-top” high power laser has been used to generate beams of accelerated electrons up to energy of 20 MeV from interactions with underdense plasmas. The energy spectrum of these beams was measured using a magnetic spectrometer and proof-of-principle experiments were performed to evaluate the suitability of these beams for electron radiography applications.

We perform systematic investigation of a new method for generating high-order harmonics, using ablation as the nonlinear medium. We place emphasis on clarifying the pump laser conditions for optimum harmonic yield. For this purpose, we use the Ti:Sapphire laser beams of the advanced laser light source (800 nm wavelength, 360 mJ total energy). We have independently varied the intensity of the prepulse (which creates the plasma ablation) and the intensity of the main pulse (which generates the harmonics), and studied their influence on the harmonic intensity. We show here that the presence of doubly ionized atoms in the ablation, created either by a strong prepulse intensity or by irradiating the main pulse, will suppress harmonic generation.

This new project relies on the capabilities collocated at Los Alamos in the Trident laser facility of long-pulse laser drive, for laser-plasma formation, and high-intensity short-pulse laser drive, for relativistic laser-matter interaction experiments. Specifically, we are working to understand quantitatively the physics that underlie the generation of laser-driven MeV/nucleon ion beams, in order to extend these capabilities over a range of ion species, to optimize beam generation, and to control those beams. Furthermore, we intend to study the interaction of these novel laser-driven ion beams with dense plasmas, which are relevant to important topics such as the fast-ignition method of inertial confinement fusion (ICF), weapons physics, and planetary physics. We are interested in irradiating metallic foils with the Trident short-pulse laser to generate medium to heavy ion beams (Z = 20–45) with high efficiency. At present, target-surface impurities seem to be the main obstacle to reliable and efficient acceleration of metallic ions in the foil substrate. In order to quantify the problem, measurements of surface impurities on typical metallic-foil laser targets were made. To eliminate these impurities, we resorted to novel target-treatment techniques such as Joule-heating and laser-ablation, using a long-pulse laser intensity of ∼ 1010 W/cm2. Our progress on this promising effort is presented in this paper, along with a summary of the overall project.

A significant effort has been made recently at CEL-V to improve laser facilities. OCTAL, the eight beam, 2 kJ laser, has been equipped with phosphate glass and KDP frequency tripling systems. PHEBUS, a two beam 20 kJ neodymium glass laser based on NOVA technology was denned and built and will be tested in early 1986 in close collaboration with Lawrence Livermore National Laboratory.

In the field of diagnostics, the development of soft X-ray emission analysis has been emphasized.

Most of the recent experimental results have been obtained at a short wave-length (0·35 μm). They deal with the effect of non-uniform illumination, 2D hydrodynamics with either plane or spherical targets, and the study of thermal transport inhibition.

The concept of fast ignition of precompressed pellets for inertial confinement fusion is presented and the main approaches are discussed. Numerical simulations of fast coronal ignition and the peculiarities of this scheme are considered in detail. Particular attention is devoted to the energy transport in the pellet corona. It is shown that fast coronal ignition will be successful only if the energy deposition by the fast electrons is anomalous over a sufficiently extended overdense region. Alternative schemes are briefly discussed.

It is not often that a new form of transportation suddenly appears and replaces what was hitherto regarded as mankind's only realistic option. In space and upper atmosphere transportation, chemical rockets have held center stage for over half a century. Tsiokolvsky's ideas led to Wernher von Braun's V2, which in turn led to the Soyuz, Apollo, and Ariane programs and the Space Shuttle. But recently theoretical and computational studies as well as a few initial experiments have pointed to a new option: laser impulse space propulsion (LISP). This may offer a more efficient and less ecologically damaging means of putting payloads into orbit. The world high-power laser community is well suited to following and aiding developments in LISP, though most practical research is still at an embryonic level. Obviously an effort of the size required to develop a laser-driven low-earth-orbit (LEO) launcher would require a multinational commitment. LISP could then be regarded as a parallel challenge to those of achieving ICF rriicrofusion yield and of improving X-ray lasers, especially in the “water window.” Any physicist or engineer involved with the latter projects would find many points in common with the former. It therefore seems appropriate to briefly review the progress made in LISP and also to communicate some recent results from high-power laser-matter experiments that have lead to conceptual designs.

Dense plasmas are produced using exploding wire discharges in water. Evolutions of radius, electrical conductivity, temperature of plasma and a shock wave in water accompanied with the explosion, are measured. Conductivities of aluminum, copper, and tungsten are compared with theoretical ones. To evaluate the equation of state, trajectories of the shock wave and the plasma boundary are compared with numerical calculations. Results show that the hydrodynamic behaviors are sensitive to the models of equation of state. Controllability of warm dense state in density-temperature diagram is discussed from the voltage-current characteristics of the wire discharges.

X-ray spectroscopical and microscopical methods are used for the determination of the spectral and spatial distribution of X-ray intensity of laser-produced plasmas. The use of Bragg reflections of two-dimensionally bent crystals enables the X-ray microscopical imaging in narrow spectral ranges (Δλ/λ = 10−4 to 10−2) with wavelengths 0.1 nm < λ > 2.6 nm. It is possible to adapt, in the X-ray microscope, the distances, magnification, position, and width of the spectral window to the special conditions of the laser facility. Manufacturing and testing of the two-dimensionally bent crystals requires a great deal of effort. It was demonstrated that a spatial resolution of about 5 μm was achieved, and that the experimentally determined reflectivity was found to be in close agreement with the dynamical theory of X-ray interferences. Due to high luminosity of the X-ray microscope, in experiments with laser-produced plasmas it was necessary to attenuate the radiation with aperture-limiting diaphragms or filters down to 0.01–1% of the original intensity in the case of a magnification of about one. Emission of the resonance line W 1–2, the intercombination line of helium-like ions, and Lyman alpha line were imaged simultaneously with a three-channel microscope. Such images form the foundation for establishing the Ne(r), Tz(r) maps.

This work reports on investigations of parameters of ion streams emitted from a plasma produced with a picosecond laser at the power densities ≥1016 W/cm2. Not many papers dealing with such investigations have been published up to now, in spite of the fact that the application of precise corpuscular diagnostics enables better learning of the physical properties of such a plasma. As a result of the investigations carried out, the average and maximum energies of Cu ions were 30 keV and 150 keV, respectively. The maximum charge of Cu ions was 13+. The dependencies of parameters of ions emitted from the plasma on the laser-pulse energy as well as on the location of the focus of the laser beam with respect to the target's surface were also found out. The results obtained from the ion measurements in relation to the results of measurements of X ray are discussed.

This paper presents an investigation of the focusing of Hermite-cosh-Gaussian laser beams in magneto-plasma by considering ponderomotive nonlinearity. The dynamics of the combined effects of nonlinearity and spatial diffraction is presented. To highlight the nature of focusing, plot of beam-width parameter vs. dimensionless distance of propagation has been obtained. The effect of mode index and decentered parameter on the self-focusing of the beams has been discussed.

The ablation of calcium sample has been studied by the optical emission spectroscopy of the evolving plasma using the fundamental, second, and third harmonic of a Nd:YAG laser, which reveals numerous transitions due to neutral and singly ionized calcium. The measurements have been performed to determine the electron temperature and electron number density and their spatial behavior. In addition, the behavior of the electron temperature and number density as a function of laser irradiance and ambient gas pressure has been studied. The processes of laser photon absorption in the plasma through inverse bremsstrahlung and photoionization have also been discussed.

A scheme for electron acceleration by two crossing chirped lasers has been proposed. An important effect of a frequency chirp of the laser is investigated. Two high intensity chirped lasers, with the same amplitude and frequency, crossing at an arbitrary angle in a vacuum, interfere, causing modulation of laser intensity. An electron experiences a ponderomotive force due to the resultant field of lasers and gains considerable energy. For a certain crossing angle, the electron gains maximum energy due to the constructive interference. A frequency chirp of the laser plays an important role during the electron acceleration in a vacuum. The electron momentum increases due to the frequency chirp. Hence, the electron energy is enhanced during acceleration.

The current capsule target design for the first ignition experiments at the NIF Facility beginning in 2009 will be a copper-doped beryllium capsule, roughly 2 mm in diameter with 160-µm walls. The capsule will have a 75-µm layer of solid deuterium-tritium on the inside surface, and the capsule will be powered by X-rays generated from a gold/uranium cocktail hohlraum. The design specifications are extremely rigorous, particularly with respect to interfaces, which must be very smooth to inhibit Rayleigh-Taylor instability growth. This paper outlines the current design, and focuses on the challenges and advances in capsule fabrication and characterization; hohlraum fabrication, and deuterium-tritium layering and characterization.

This paper reports on the status of the PHELIX petawatt laser which is built at the Gesellschaft fuer Schwerionenforschung (GSI) in close collaboration with the Lawrence Livermore National Laboratory (LLNL), and the Commissariat à l'Energie Atomique (CEA) in France. First experiments carried out with the chirped pulse amplification (CPA) front-end will also be briefly reviewed.

Arbitrarily heavy cluster ion beams (CIB) are examined for the purpose of driving directly or indirectly an ICF compression. This paper provides an overview of cluster production, and of their interaction with cold and hot matter. Fragmentation is also considered. Concepts and ideas of interest for further investigations are identified and delineated. A connection is made with a CIB interaction experiment planned at Orsay. It is conjectured that CIB should experience enhanced stopping when compared to their atomic counterparts under similar conditions.

Laser produced ion beams have a large divergence angle and a wide energy spread. To our knowledge, this is the first demonstration of collimation and monochromatisation of laser accelerated proton beams, using a permanent quadrupole magnet lens system. It acts as a tunable band pass filter by collimating or focusing the protons with the same energy. Because it gathers nearly the whole proton emission, a strong enhancement of the beam density appears. For the collimated beam, an increase of the proton density in the (3.7 ± 0.3) MeV energy band up to a factor of ~30, from possible 40, relative to the non-collimated beam is demonstrated. With the help of this simple, reliable, and well established technique new perspectives will be opened for science and technology, monoenergetic ion beams can be attained in any lab, where a source of laser accelerated ions exist. This finding enables to apply afterward well known beam steering techniques to the formed ion beam, which are applied in conventional accelerators to manipulate the beam parameters or to transport the beams and make them use in many application.