At the start of a new volume I want to take the opportunity to thank the associate editors and the editorial board members whose terms ended recently for their many years of service to the scientific community and to this journal especially. I personally had a lot of help from all of them, and I dare to ask for their continued support for this journal. The attentive reader may notice quite a change in the editorial team. Therefore this is also the opportunity to welcome the new board members and to wish them success for their editorial work.

The present 28th ECLIM in Rome is a continuation of the series of conferences that started in Frascati, Italy in 1966. These conferences deal with the interdisciplinary subjects of laser interaction with matter, related not only to basic science but also to a wide range of applications. ECLIM is an independent scientific conference, free of any institutional or political influence, keeping science without boundaries.

We address the issues of collective stopping for intense relativistic electron beams (REB) used to selectively ignite precompressed deuterium + tritium (DT) fuels. We investigate the subtle interplay of electron collisions in target as well as in beam plasmas with quasi-linear electromagnetic growth rates. Intrabeam scattering is found effective in taming those instabilities, in particular for high transverse temperatures.

We have developed a compact, 14.7 nm, sub-5 ps X-ray laser source at Lawrence Livermore National Laboratory (LLNL) together with a Mach-Zehnder type diffraction grating interferometer built at Colorado State University for probing dense, high intensity laser-produced plasmas. The short wavelength and pulse length of the probe reduces refraction, absorption effects within the plasma and minimizes plasma motion blurring. This unique diagnostic capability gives precise two-dimensional (2D) density profile snapshots and is generating new data for rapidly evolving laser-heated plasmas. A review of the results from dense, mm-scale line focus plasma experiments will be described with detailed comparisons to hydrodynamic simulations.

In this paper, we suggest the creation of a nanoparticles and nanotubes by using the interaction of a femtosecond laser with a solid target in a vacuum. A simple model is used to predict the optimal target and the laser parameters for the production of efficient nanoparticles. At the Soreq laboratory, experiments are performed with aluminium and carbon targets using a femtosecond laser. The irradiated targets are composed of either a thin layer of aluminium or of carbon, deposited on a transparent heat-insulating glass substrate. The nanoparticle debris is collected on a silicone wafer for X-ray diffraction (XRD), for scanning electron microscopy (SEM), and for atomic force microscopy (AFM). For transmission electron microscopy (TEM), the debris is caught on a copper grid covered on one side with a carbon membrane. Our experiments confirm the creation of crystal nanoparticles for aluminium and nanotubes for carbon experiments.

Strongly shocked cylindrically convergent implosions were conducted on the OMEGA laser. The directly driven targets consist of a low-density foam core and an embedded aluminum shell covered by an epoxy ablator. The outer surface of the aluminum shell has imposed single-mode perturbations with wave numbers k = 0.25, 0.7, 1.05, and 2.5 (rad/μm) and initial amplitudes η0 /λ = 0.04, 0.11, 0.33, and 0.4. In our convergent geometry, perturbation growth without evidence of saturation, for η/λ as large as 4.5 is observed for k < 1. For k > 1 growth rate scaling with wavenumber breaks down and transition to turbulence is suggested.

A diffraction limited focal spot is used to create a single speckle in a preformed plasma. The single speckle, or hot spot, is the simplest irreducible element for studying laser plasma interactions. Using the single hot spot configuration, the nonlinear behavior of SRS driven Langmuir waves has been investigated in both a fluid dominated and a kinetic regime. A transition between the two regimes has been observed as a function of kλD where k is the Langmuir wave-number and λD is the Debye length.

Irradiation of solid targets by short laser pulses can result in a production of fast ions. In this paper, two production modes are discussed: the controlled amount of matter mode (CAM) and the open amount of matter mode (OAM). The CAM mode is based on laser energy transfer to a controlled amount of matter before the target becomes transparent to the laser light due to the gas-dynamical expansion. For the CAM mode, it is presented a model that allows determining the target parameters, the focusing conditions, and the pulse duration as a function of the laser pulse energy, of the aimed energy per nucleon and of the energy transfer efficiency to the target. The conditions to be this mode experimentally addressed are indicated. The OAM mode relies on the irradiation of a target with large ion content by a short laser pulse; in this case, a small amount of fast ions is emitted from the rear and lateral sides of the target depending on the laser pulse and focusing parameters. For this mode, observed in several experiments, a theoretical discussion is presented. Special attention is devoted to the target normal sheath acceleration (TNSA) and to expansion wave (EW) mechanisms. The EW process is discussed in the framework of a two-temperature isothermal model and some peculiar hydrodynamic processes are discussed.

Recently a new fast ignitor concept has been proposed by Velarde et al. (2003) that uses only one energy drive. In this concept, the ignition is induced by the collision of high velocity matter accelerated inside a conical guide. The first model used a jet produced by illuminating a conical shape with a laser or X-rays. On the other hand, in the shell impact concept, the compressed deuterium-tritium fuel is ignited by a separately imploded shell traveling in a guiding cone. In this article, we will study the first design, jet driven concept that have been developed during this year. We use for this work the Arwen code (Ogando & Velarde, 2001; Rendleman et al., 2000), with two-dimensional (2D) multi-group radiation transport. The main parameter is to analyze the specific power transmitted to the target during the collision. Problems with the designs are the guide integrity during the collapse, the radiation preheating, and the average efficiency of the process, etc. which we will address as well.

Intense heavy ion beams from the Gesellschaft für Schwerionenforschung (GSI, Darmstadt, Germany) accelerator facilities, together with two high energy laser systems: petawatt high energy laser for ion experiments (PHELIX) and nanosecond high energy laser for ion experiments (NHELIX) are a unique combination to facilitate pioneering beam-plasma interaction experiments, to generate and probe high-energy-density (HED) matter and to address basic physics issues associated with heavy ion driven inertial confinement fusion. In one class of experiments, the laser will be used to generate plasma and the ion beam will be used to study the energy loss of energetic ions in ionized matter, and to probe the physical state of the laser-generated plasma. In another class of experiments, the intense heavy ion beam will be employed to create a sample of HED matter and the laser beam, together with other diagnostic tools, will be used to explore the properties of these exotic states of matter. The existing heavy ion synchrotron facility, SIS18, deliver an intense uranium beam that deposit about 1 kJ/g specific energy in solid matter. Using this beam, experiments have recently been performed where solid lead foils had been heated and a brightness temperature on the order of 5000 K was measured, using a fast multi-channel pyrometer that has been developed jointly by GSI and IPCP Chernogolovka. It is expected that the future heavy ion facility, facility for antiprotons and ion research (FAIR) will provide compressed beam pulses with an intensity that exceeds the current beam intensities by three orders of magnitude. This will open up the possibility to explore the thermophysical and transport properties of HED matter in a regime that is very difficult to access using the traditional methods of shock compression. Beam plasma interaction experiments using dense plasmas with a Γ-parameter between 0.5 and 1.5 have also been carried out. This dense Ar-plasma was generated by explosively driven shockwaves and showed enhanced energy loss for Xe and Ar ions in the energy range between 5.9 to 11.4 MeV.

For achieving practically useful laser fusion energy generation, it is necessary to have a M-J laser system with a repetition rate over 10 Hz. We believe that a beam combination method using stimulated Brillouin scattering phase conjugate mirrors (SBS-PCM) is one of the most practical techniques for achieving the high repetition rate of the high power laser. In this paper, we present the recent results about the beam combination laser, such as SBS reflectivity depending on the mode structure, the cross type isolator, and the phase-locking technique. For the phase-locking technique, especially, the self-phase-locking is proposed and its result is discussed.

Electron ponderomotive acceleration in a vacuum by a short-pulsed laser of TEM (1, 0) + TEM (0, 1) mode is studied in this paper using a 3-dimensional (3D) particle simulation. It was found that the laser can trap electrons in transverse and accelerate them with the longitudinal ponderomotive force at the same time. Through this electron trapping and acceleration scheme of TEM (1, 0) + TEM (0, 1) mode laser, the electron bunch is confined well in transverse and compressed remarkably in longitudinal. Therefore, a high energy, high density, and low emittances electron bunch is generated. For example, the result shows that for a laser with intensity of a0 = eE0 /mωc = 10, the laser spot size of w0 = 15λ, and the laser pulse length of Lz = 10λ, the maximum energy gain reaches 301 MeV and the average energy 57.7 MeV. The electron bunch transverse radius is about 350λ and the longitudinal size about 20λ. The property of this accelerated bunch is improved compared with that generated by the laser of TEM (0, 0) mode.

This paper presents an effect of relativistic mutual interaction of two laser beams of different frequencies on the growth of a laser ripple in laser produced plasmas. The nonlinearity due to relativistic mass variation depends not only on the intensity of one laser but also on the second laser. Therefore, one laser beam affects the dynamics of the second beam and hence a mutual nonlinear interaction (cross-focusing) takes place. The dynamical equations governing the laser intensity of two laser beams and the perturbation present on one laser beam (ripple) have been set up and a numerical solution has been presented for typical laser plasma parameters. It is found that a change in the intensity of the second laser beam can affect the growth of the laser ripple significantly. This study is important in plasma beat wave excitation and collective laser particle accelerators.

The study of heavy ion stopping dynamics using associated K-shell projectile and target radiation was the focus of the reported experiments. Ar, Ca, Ti, and Ni projectile ions with the initial energies of 5.9 and 11.4 MeV/u were slowed down in quartz and arogels. Characteristic radiation of projectiles and target atoms induced in close collisions was registered. The variation of the projectile ion line Doppler shift due to the ion deceleration measured along the ion beam trajectory was used to determine the ion velocity dynamics. The dependence of the ion velocity on the trajectory coordinate was measured over 70–90% of the ion beam path with a spatial resolution of 50–70 μm. The choice of SiO2 aerogel with low mean densities of 0.04–0.15 g/cm3 as a target material, made it possible to stretch the ion stopping range by more than 20–50 times in comparison with solid quartz. It allowed for resolving the dynamics of the ion stopping process. Experimentally, it has been proven that the fine porous nano-structure of aerogels does not affect the ion energy loss and charge state distribution. The strong increase of the ion stopping range in aerogels made it possible to resolve fast ion radiation dynamics. The analysis of the projectile Kα-satellites structure allows supposing that ions propagate in solid in highly exicted states. This can provide an experimental explanation for so called gas-solid effect.

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.

Since their discovery, laser accelerated ion beams have been the subject of great interest. The ion beam peak power and beam emittance is unmatched by any conventionally accelerated ion beam. Due to the unique quality, a wealth of applications has been proposed, and the first experiments confirmed their prospects. Laser ion acceleration is strongly linked to the generation and transport of hot electrons by the interaction of ultra-intense laser light with matter. Comparing ion acceleration experiments at laser systems with different beam parameters and using targets of varying thickness, material and temperature, some insight on the underlying physics can be obtained. The paper will present experimental results obtained at different laser systems, first beam quality measurement on laser accelerated heavy ions, and ion beam source size measurements at different laser parameters. Using structured targets, we compare information obtained from micro patterned ion beams about the accelerating electron sheath, and the influence of magnetic fields on the electron transport inside conducting targets.

The recently proposed backward Raman laser amplification scheme utilizes the stimulated Raman backscattering in plasma of a long pumping laser pulse to amplify a short, and frequency downshifted seed pulse. The output intensity for this scheme is limited by the development of forward Raman scattering (FRS) or modulational instabilities of the highly amplified seed. Theoretically, focused output intensities as high as 1025 W/cm2, and pulse lengths of less than 100 fs, could be accessible by this technique for 1 μm lasers—an improvement of 104–105 in focused intensity over current techniques. Simulations with the particle-in-cell (PIC) code Zohar are presented, which investigate the effects of FRS and modulational instabilities, and of Langmuir wave breaking on the output intensity for Raman amplification. Using the intense seed pulse to photoionize the plasma simultaneous with its amplification (and hence avoid plasmas-based instabilities of the pump) is also investigated by PIC simulations. It is shown that both approaches can access focused intensities in the 1025 W/cm2 range.

A beam combination laser with stimulated Brillouin scattering-phase conjugate mirrors (SBS-PCMs), which is expected to produce a high output energy and power with a repetition rate over 10 Hz, is a candidate for a practically useful laser fusion driver in the future. In order to develop the beam combination laser with SBS-PCMs, it is necessary to control the phase of each SBS wave whose phases are known as inherently random. We have proposed a new phase control technique and demonstrated experimentally that the relative phase difference between two SBS waves can be controlled to a certain value and locked to it with an accuracy less than λ/4. Additionally we have proposed and demonstrated a new technique to preserve the pulse shape of the SBS wave. Based on these experimental results, we have proposed two schemes of the new schemes for the high repetition and high energy/power beam combination laser system (laser fusion driver) using the SBS-PCMs of amplitude division and wave-front division techniques, which can operate with repetition rate over 10 Hz, in this paper.