The process of induced bremsstrahlung is studied and it is found that anisotropy in the electron distribution can lead to the amplification of radiation. The gain rate is ,Λ where ν is the electron-ion collision frequency, ωp and ω the plasma and radiation frequency, and Λ a numerical factor which is positive only for anisotropic distributions.

The growth of the Rayleigh-Taylor instability in three dimensions is ex amined during the deceleration phase of an inertial confinement fusion implosion. A detailed discussion of the three-dimensional hydrocode, PLATO, is presented. A review of previous calculations is given, concentrating on theshape of the R-T instability in three dimensions. Results of the growth rate during the linear phase, the saturation amplitude, and the nonlinear evolution are presented.

In this article we describe a new ray-trace code. This code is a three-dimensional description of the beam propagation, including the half cavity mirror. It is based on the integration of the ray equation and on the calculation of the intensity along the plasma. It works as a postprocessor of the hydrodynamic/atomic code “EHYBRID,” which calculates the time evolution of the gain, emissivity, electronic density, and the width of the plasma. We present results obtained on different schemes of X-ray laser generation.

Experimental spectra of hot dense plasmas of aluminium produced by the interaction of a subpicosecond laser with solid targets at 1016 and 5 × 1017 W/cm2 are analyzed and discussed. A detailed analysis of the K-shell spectra is given through time-dependent calculations of atomic physics postprocessed to Fokker-Planck calculations of the laser-matter interaction. The non-Maxwellian character of the electron distribution function is shown. An evaluation of the electronic density and of the ion temperature 7i will be presented through Stark line broadening calculations. An X-ray spectrum from a Tantalum target also will be presented along with a preliminary interpretation.

Stimulated rotational Raman scattering (SRRS) limits the effective transmission distances of the high-energy and high-power laser pulses in laser–fusion systems and other applications. A simple and practical method of suppressing SRRS process by controlling the polarization direction of Stokes light is proposed. For a narrowband, linearly polarized, flat-topped laser pulse of 351 nm with intensity of 2 GW/cm2 and width of 3 ns, the SRRS threshold distance in air is lengthened to 30.0 m from 16.2 m easily using the method. Simulation results demonstrate that the method is also applicable for broadband laser.

Ignition with the help of a shock wave is performed by the interaction of accelerated plasma block by a petawatt-picosecond (PW-ps) laser, with a solid-state density fuel that it is a new possibility for achieving controlled fusion by inertial confinement. The unexpected production of plasma blocks provides new access to the ignition of solid-state density fuel according to the Chu hydrodynamic model. When the produced plasma block by the PW-ps laser hits the main fuel due to the density differences between the plasma block and the main fuel of the shock wave, this progressive wave increases the density of solidified fuels and reduces the energy of the ignition threshold and increases the flammability. In this study, a new discovery of shock waves has been observed leading to the resonance phenomenon. Nuclear heat shock waves resonance in the side-on ignition of fuel in the internal layer of fuel at x ≠ 0 appears from the exact solution of the hydrodynamic equations with respect to the density profile. This important finding achieves the required ignition temperature for solid-state fuel deuterium–tritium (D–T) in certain energies, with a significant increase due to the resonance of thermonuclear waves. This discovery will facilitate practical experiments on the ignition of advanced solid-state fuels with the accelerated plasma blocks by a PW-ps laser at certain energies.

The behavior of the stimulated Raman scattering is investigated in a laser-irradiated plasma with an inhomogeneous density profile, by means of wave-coupling simulations. In the case of a regular hydrodynamic-like profile, a spectral broadening is observed when the laser irradiance is increased and is found to result from a coupling between the convective and the absolute Raman scattering, via pump depletion. In the case where a short-scale modulation of the density is superimposed on the profile, the spectrum is strongly influenced by the propagation velocity of the modulation and by the sinusoidal/chaotic nature of the modulation.

The quantum behavior of the system composed of an electron in an electromagnetic field is described by the Dirac equation, whose solution is a wave function represented by a column matrix with four components. We prove, without using any approximation, that these components can be put in a form which reveals directly the values of the electron energy, laser beam intensity, or amplitude of the electric field intensity, for which the quantum electrodynamics effects are generated. Our results are in good agreement with the experimental data reported in the literature. We prove that the four components of the wave function verify the continuity equation of quantum electrodynamics. Our treatment is in good agreement with the Compton relation. We show that the interaction of electrons with laser beams could be modeled using classical approaches regardless of the laser beam intensity as long as the electrons are non-relativistic, in agreement with published experimental data.

Sodium laser blow-off plasma of low temperature (in the 1-eV range) is generated by laser intensities of 108–5.109 W cm−2. Imprisonment of resonant laser light has been observed. These experiments show that basic processes of interaction of radiation with level populations can be studied in the visible range, where the atomic levels have longer lifetimes than the ionic ones in hot plasmas, corresponding to X-ray generation. The imprisonment and resonant effects with various experimental parameters were investigated together with the nonresonant scattering on fragments.

Recent advances of the photon kinetic theory are illustrated here, with examples taken from plasma physics (forward Raman scattering), and from nonlinear optics (self-phase modulation). This theory can provide a unified view of nonlinear optical phenomena involving photon beams with an arbitrary spectrum.

We present results of studies of the behavior of a laser-produced plasma in a strong external transverse magnetic field of above 10 T in induction generated from a flat teflon target at the laser power densities of about 1014 W/cm2. In the measurements of plasma parameters, a two-channel automated interferometric system (Pisarczyk et al. 1994) was applied. The interferometric measurements have shown that the transverse magnetic field induces an asymmetry of the plasma distinctly apparent in the interferograms registered in two mutually perpendicular directions. Due to the lack of axial symmetry of the plasma, the Abel's transformation could not be applied in quantitative processing of the interferograms. To reconstruct a spatial distribution of electron density in a plasma stream of disturbed axial symmetry, a methodology prepared for this experiment was used. Analyzing the spatial and temporal distributions of electron concentration obtained in the transverse magnetic field, it has been proved that the factor responsible for the disturbance of the axial symmetry of the plasma is the Rayleigh–Taylor (R–T) instability corresponding to the ion unmagnetization state.

In this paper, a new method for efficient generation of high-energy ion bunches via laser-induced cavity pressure acceleration (LICPA) is examined using one-dimensional particle-in-cell code PIC1D. It is found that for high laser beam intensities of the order of 1022 W/cm2 and for circular light polarization, a substantial increase in parameters of the accelerated ions is obtained when the target is placed inside a special cavity, into which the laser beam is introduced by a small hole. As compared to the pure radiation pressure acceleration scheme, the LICPA scheme leads to an increase in ion energies and the laser-to-ions energy conversion efficiency while the width of the ion energy spectrum are similar for both the schemes. Such a tendency was observed for all carbon targets (from 2 µm to 0.2 µm thick) investigated in the paper. The results of PIC1D simulations agree very well with predictions of the suitably generalized light sail model.

This issue of Laser and Particle Beams contains 27 contributed articles based on presentations given at the eighth International Workshop on the Physics of Compressible Turbulent Mixing (IWPCTM) (see http://www.llnl.gov/IWPCTM), held at the California Institute of Technology, Pasadena, California from December 9 to 14, 2001, and organized jointly by the Lawrence Livermore National Laboratory (LLNL) and the California Institute of Technology. This conference is the eighth in a biennial series of conferences on the general subject of experimental, numerical, and theoretical studies of compressible turbulent mixing, initiated by LLNL in the late 1980s. Previous conferences were held in Princeton, New Jersey (1988), Pleasanton, California (1989), Royaumont, France (1991), Cambridge, United Kingdom (1993), Stony Brook, New York (1995), Marseille, France (1997), and St. Petersburg, Russia (1999). The ninth IWPCTM is to be held at the University of Cambridge in 2004.

A novel composite optical phase conjugator that combines Brillouin-enhanced four-wave mixing (BEFWM) and stimulated Brillouin amplification (SBA) in a compact structure is reported. A phase-conjugate wave seed is generated by BEFWM process with characteristics such as fast response, high conjugate fidelity and stability, then it is magnified by SBA with high energy-conversion efficiency. As a result, advantages of BEFWM and SBS can be realized at the same time. This composite conjugator has potentials for high-peak and high-average power laser applications, especially for short pulse or steep leading-edge pulse laser systems. Feasibility of this BEFWM-SBA mechanism is verified in theoretical simulations and demo experiments.

An experiment has been performed with the LULI Multi-TeraWatt Laser. The acceleration of electrons injected in a plasma wave generated by the laser wakefield mechanism has been observed with a maximum energy gain of 1.5 MeV. It has been shown that the electrons deflected during the interaction, could scatter on the walls of the experimental chamber, and fake a high-energy signal. A special effort has been given in the electron detection to separate the accelerated electrons signal from the background noise.The experimental results agree with theoretical predictions and numerical simulations when 3D effects on the electron beam are taken into account.

In inertial fusion, one of scientific issues is to reduce an implosion non-uniformity of a spherical fuel target. The implosion non-uniformity is caused by several factors, including the driver beam illumination non-uniformity, the Rayleigh–Taylor instability (RTI) growth, etc. In this paper, we propose a new control method to reduce the implosion non-uniformity; the oscillating implosion acceleration δg(t) is created by pulsating and dephasing heavy-ion beams (HIBs) in heavy-ion inertial fusion (HIF). The δg(t) would reduce the RTI growth effectively. The original concept of the non-uniformity control in inertial fusion was proposed in [Laser Part. Beams (1993) 11, 757–768]. In this paper, it was found that the pulsating and dephasing HIBs illumination provide successfully the controlled δg(t) and that δg(t) induced by the pulsating HIBs reduces well the implosion non-uniformity. Consequently the pulsating HIBs improve a pellet gain remarkably in HIF.

The interaction of light with the intergalactic plasma produces the Hubble red shift versus distance relationship. This interaction also produces an isotopic long wavelength background radiation from the plasma. Intrinsic red shifts in quasars and other objects are similarly explained, showing why they are exceptions to Hubble's law. Because the red shift is not doppler-shifted, big bang cosmological models should be replaced with static models.