A new version of the numerical code KALOS has been developed to solve the Vlasov-Fokker-Planck equation for electrons as well as EM wave propagation. KALOS represents the electron distribution function in momentum space by an expansion in spherical harmonics. Its unique features make possible simultaneous investigations of fast electron generation and transport and the collisional evolution of thermal particles, including the return current of cold electrons. We report here on results obtained in one spatial dimension. Absorption of 100fs, 1015 W/cm2 laser pulses has been studied at normal incidence in sharp-edged dense plasmas. We have studied the effect on absorption of energy transport into the target as well as the deviation of the electron distribution function from Maxwellian. It is shown that it is necessary to take into account collisional heat transport into the target in order to correctly model the absorption rate at the front surface.

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.

This paper will present a novel genetic-algorithm-based code (GASPED), developed for the analysis of fine features (e.g., satellite structure and line shifts) in X-ray spectra emitted by hot dense plasmas. The problem dependent modification of standard genetic-algorithm concepts allows efficient decomposition of spectra in concrete physical terms, such as resonance and intercombination lines, dielectronic satellites, or prospective nuclear transitions. Two examples of the code application demonstrate the proposed approach. High resolution K-shell spectra emitted from He- and Li-like Al ions immersed in dense, constrained-flow plasma are decomposed into individual pseudo-Voigt components, by using anticipatory theoretical knowledge of the satellite structure simulated by the multilevel collisional-radiative code (MARIA). Line shifts of the He-like resonance and intercombination line are deduced assuming the aggregate plasma-induced shifts of the parent lines and their satellites. The trend in the frequency shifts observed as a function of the variable plasma parameters qualitatively follows the theoretical predictions. The found variations of the exchange energy between the singlet and triplet levels provide a new impact for the line shift theories. The second example concerns the search for low-lying nuclear transitions in hot dense laser-produced plasmas. The spectra of highly ionized Ta are decomposed by combining the GASPED code with results of ab initio atomic data calculations performed by the RELAC code. Upper limits for observation of the controversial radiative decay of Ta nuclei at 6.238 eV are estimated.

We will consider relativistic electron beam interacting with plasma and study the electromagnetic instabilities obtained for arbitrarily oriented wave vectors ranging from two-stream to filamentation instabilities. For these unstable modes, we will study every temperature effects, namely beam and plasma normal, and parallel temperatures. Temperatures are supposed to be non-relativistic and modeled through water bag distributions. It is found that only normal beam temperature and parallel plasma temperature have a significative influence over the growth rates for wave vector making an angle with the beam larger than a critical angle θc which is determined exactly. The largest growth rate being reached for a wave vector making an angle with the beam smaller than θc, it is not damped by any kind of temperatures. We finally explore collisions effects and show they can reduce the largest growth rate.

The k-L turbulence model, where k is the turbulent kinetic energy and L represents the turbulent eddy scale length, is a two-equation turbulence model that has been proposed to simulate turbulence induced by Rayleigh-Taylor (RT) and Richtmyer Meshkov (RM) instabilities, which play an important role in the implosions of inertial confinement fusion (ICF) capsule targets. There are three free parameters in the k-L model, and in this paper, I calibrate them independently by comparing with RT and RM data from the linear electric motor (LEM) experiments together with classical Kelvin-Helmoholtz (KH) data. To perform this calibration, I numerically solved the equations of one-dimensional (1D) Lagrangian hydrodynamics, in a manner similar to that of contemporary ICF codes, together with the k-L turbulence model. With the three free parameters determined, I show that the k-L model is successful in describing both shear-driven and buoyancy-driven instabilities, capturing the experimentally observed separation between bubbles and spikes at high Atwood number for the RT case, as well as the temporal mix width recorded in RM shock tube experiments.

Laser fusion requires very high energy/power output with high repetition rate over 10 Hz, which is very difficult with the current laser technologies. However, the recent research work on the phase controlling of the stimulated Brillouin scattering wave enables the realization of this kind of laser fusion driver. The recent progress of controlling the phase has been successfully demonstrated by the self-generated density modulation method proposed by one of the authors (Kong). Nevertheless, it showed a long-term fluctuation of the phase because of the long-term fluctuation of the density of the SBS medium due to the thermal fluctuation. This long-term thermal fluctuation is inevitable a fact in nature. The authors used a specially designed stabilizing system for the phase controlling system, which has the PZT control of the mirror for phase controlling SBS-PCM (the so-called feedback mirror). This system stabilizes the phase controlling system very well for more than 1 h. This technique will help the laser fusion driver to be realized sooner than expected. In addition, we propose a similar scheme to be applied to the ultra-fast pulse laser system, which must operate at high repetition rate for the laser fusion energy power plant.

Electron collision strengths for electron-impact excitation of Li-like and Al ion are evaluated in close-coupling approximation using the multi-channel R-matrix method. Five LS target eigenstates are included in the expansion of the total wave function, consisting of the two n = 2 states with configurations of 1s22s, 1s22p, and three n = 3 states with configurations 1s23s, 1s23p, and 1s23d. Collision strengths are obtained in LS coupling using FARM code and in intermediate coupling scheme using the SUPERSTRUCTURE program. The effective collision strengths are calculated as function of temperature, up to a temperature that does not exceed half of the maximum energy in the R-matrix run.

A new theory for the nuclear forces for confining the nucleons in a nucleus was derived from a generalization of the Debye layer as known from the plasma ablation at laser irradiation where the temperature is substituted by the Fermi energy of the statistics of nucleons. The first convincing proof is by using the empirical density of the nucleons defining their Fermi energy to arrive at a Debye length of about 3 fm as measured by Hofstadter for the decay of the nucleon density at the surface of heavy nuclei. Taking then the surface tension of plasmas with the same steps of substituting temperature by Fermi energy, the surface energy of nuclei is always too small against the nucleon enthalpy to confine the nucleons until equilibrium is reduced at about such high densities reproducing the well known radii of nuclei. The Hofstadter decay can be interpreted as the inhomogeneous wave of the nucleons by Wigner scattering at the nuclear surface similar to the Goos-Haenchen effect. By this way, nuclei are possible only until uranium or curium by a Boltzmann equilibrium process explaining the endothermic generation of heavy nuclei. At about six times higher nucleon density, the Fermi statistics changes into its relativistic branch resulting in a surface energy always smaller than before, and the mass and density independence indicates that one cannot distinguish between the state as in a neutron star or as a quark-gluon plasma. The steps from the ablation of laser produced plasma via a quantum theory of the surface tension in metals to the new nuclear force theory are explained. A consideration of the magic numbers indicates a quark-shell structure of nuclei.

For biological hard tissues as well as for artificial restoration materials, ultra-short laser pulses (USLP) have proven their suitability for ablation with negligible collateral damage providing many advantages. For this paper, it was the aim to investigate the suitability of scanned USLP for the ablation of dental restorative materials compared to the microsecond pulses of conventional Erbium lasers. Scanning electron microscopy allowed analyzing the quality of the cavity surfaces with respect to structural properties as well as temperature exposition. Quantitative results about the ablation efficiency are given for different laser parameters on dental hard tissue and a broad variety of dental restoration materials, the latter being reported for the first time.

This work describes an inductive energy storage scheme intended for power multiplication at mega-Ampere currents. The key power multiplication element of the scheme is an opening switch generating the voltage of inductive origin. The switch represents an additional volume with magnetically accelerated solid-state or plasma conductor between the generator and the load. Motion of the conductor increases the inductance of the volume. A sufficiently fast increase of this inductance at the end of magnetic energy storage time ensures power multiplication. A critical requirement for the accelerated conductor is the possibility of temporal profiling of the inductance increase. A proof-of-principle experiment at GIT12 shows that such profiling is possible. We suggest a simple analysis of the scheme efficiency and illustrate this analysis for a multi-mega-Ampere class generator. The scheme is alternative to existing inductive energy storage technologies for pulsed-power conditioning at high currents.

Laser-induced breakdown spectroscopy (LIBS) in combination with a conventional mine prodder is applied for remote detection of explosives and mine housing materials. High power subnanosecond laser pulses (pulse power Ep = 0.6 mJ and pulse duration Δt = 650 ps) at 1064 nm with a typical repetition rate of 10 kHz are generated by using a passively Q-switched Cr4+:Nd3+:YAG microchip-laser as seed-laser for an Yb-fiber amplifier. In the present investigation, the ratios of “late” and “early” LIBS intensities for the cyanide (CN) plasma emission at 388 nm and for the C-emission at 248 nm are used for data analysis. This allows the classification of different explosives and mine casing materials under real time conditions and also similar applications to materials processing.

It is proposed that it is possible to amplify the energy of a pulsed laser beam by imploding it inside a capillary metallic liner. If imploded with megaampere currents by the pinch effect, implosion velocities up to ∼3 × 108 cm/s can be reached, imploding a few cm long liner with an inner radius of 2 × 10−3 cm in about ∼10−10 s. If the liner radius can be imploded by 30-fold, the laser pulse would in the absence of absorption losses into the linear wall be amplified 1000-fold. Because the amplification is through the conversion from longer to shorter wave lengths, the concept offers the prospect of intense short wave length laser pulses in the far ultraviolet and soft X-ray domain. Apart from the direct drive laser beam compression by the pinch effect, an alternative indirect drive through the conversion of the electric pulse power into soft X-rays is possible as well. The limitations of this concept are the absorption losses into the liner wall, and ways to overcome these losses are presented. The most important application of the proposed laser amplification scheme might be for the fast ignition of various inertial confinement fusion schemes. An integrated fast ignition inertial confinement fusion concept using the indirect drive is also presented.

Radiative shock waves are observed around astronomical objects in a wide variety of environments, for example, they herald the birth of stars and sometimes their death. Such shocks can also be created in the laboratory, for example, by using energetic lasers. In the astronomical case, each observation is unique and almost fixed in time, while shocks produced in the laboratory and by numerical simulations can be reproduced, and investigated in greater detail. The combined study of experimental and computational results, as presented here, becomes a unique and powerful probe to understanding radiative shock physics. Here we show the first experiment on radiative shock performed at the PALS laser facility. The shock is driven by a piston made from plastic and gold in a cell filled with xenon at 0.2 bar. During the first 40 ns of the experiment, we have traced the radiative precursor velocity, that is showing a strong decrease at that stage. Three-dimensional (3D) numerical simulations, including state-of-art opacities, seem to indicate that the slowing down of the precursor is consistent with a radiative loss, induced by a transmission coefficient of about 60% at the walls of the cell. We infer that such 3D radiative effects are governed by the lateral extension of the shock wave, by the value of the opacity, and by the reflection on the walls. Further investigations will be required to quantify the relative importance of each component on the shock properties.

The properties of plasma (proton) block driven by the laser-induced skin-layer ponderomotive acceleration (S-LPA) mechanism are discussed. It is shown that the proton density of the plasma block is about a thousand times higher than that of the proton beam produced by the target normal sheath acceleration (TNSA) mechanism. Such a high-density plasma (proton) block can be considered as a fast ignitor of fusion targets. The estimates show that using the S-LPA driven plasma block, the ignition threshold for precompressed DT fuel can be reached at the ps laser energy ≤ 100 kJ.

In this paper, the effect of a relativistically intense Gaussian laser pulse, on the propagation of electron plasma wave is studied. The nonlinear effects considered here are the relativistic decrease of the plasma frequency and the ponderomotive expelling of the electrons. Modified coupled equations for laser and electron plasma wave are derived from fluid equations. These coupled equations are solved analytically and numerically to study the laser intensity in the plasma and the variation of amplitude of the excited electron plasma wave. It is seen that the effect of including the ponderomotive nonlinearity is significant on the excitation of plasma wave. This should affect the number of energetic electrons and their energy range on account of wave particle interaction.

This paper reports the formation of low-energy low-divergence pulsed indium atomic beam via ablation of thin film by illumination from the rear side with second harmonic of Q-switched Nd:YAG laser under high vacuum (∼10−5 Torr). Angular divergence of ablated indium atomic, reflectivity modulation of thin film due to ablation, and longitudinal atomic velocity of ablated beam were studied as a function of laser fluence. Atomic force microscope scans of the deposited multiple shots of pulsed atomic beams show the formation of “nano-hills.”

Laser-Compton scattering (LCS) experiments were carried out at the Idaho Accelerator Center (ICA) using the 5 ns (FWHM) and 22 MeV electron beam. The electron beam was brought to an approximate head-on collision with a 7 ns (FWHM), 10 Hz, 29 MW peak power Nd:YAG laser. We observed clear and narrow X-ray peaks resulting from the interaction of relativistic electrons with the 532 nm Nd:YAG laser second harmonic line on top of a very low bremsstrahlung background. We have developed a method of using LCS as a non-intercepting electron beam monitor. Unlike the method used by Leemans et al. (1996), our method focused on the variation of the shape of the LCS spectrum rather than the LCS intensity as a function of the observation angle in order to extract the electron beam parameters at the interaction region. The electron beam parameters were determined by making simultaneous fits to spectra taken across the LCS X-ray cone. We also used the variation of LCS X-ray peak energy and spectral width as a function of the detector angles to determine the electron beam angular spread, and direction and compared the results to the previous method. Experimental data show that in addition to being viewed as potential bright, tunable and monochromatic X-ray source, LCS can provide important information on electron beam pulse length, direction, energy, angular, and energy spread. Since the quality of LCS X-ray peaks, such as degree of monochromaticity, peak energy and flux, depends strongly on the electron beam parameters, LCS can therefore be viewed as an important non-destructive means for electron beam diagnostics.

The design of a two-stage compact GeV electron accelerator is presented. The accelerator is as follows: (1) an ultra-short electron bunch is produced in a state-of-the-art laser-plasma accelerator (injector stage), (2) it is injected into an accelerating stage consisting of a centimeter length low density plasma interacting with a petawatt laser pulse. The parameters for the injector are taken from recent experimental results showing that high quality, ultra-short, and quasi-monoenergetic electron beams are now being produced in laser-plasma accelerators. Simulations performed with WAKE show that this method can lead to the production of high quality, monoenergetic, and sub-50 fs electron bunches at the GeV energy level.

An intense and focused heavy ion beam is a suitable tool to generate high energy density in matter. To compare results with simulations it is essential to know beam parameters as intensity, longitudinal, and transversal profile at the focal plane. Since the beam's energy deposition will melt and evaporate even tungsten, non-intercepting diagnostics are required. Therefore a capacitive pickup with high resolution in both time and space was designed, built and tested at the high temperature experimental area at GSI. Additionally a beam induced fluorescence monitor was investigated for the synchrotron's (SIS-18) energy-regime (60–750 AMeV) and successfully tested in a beam-transfer-line.

This paper presents theoretical results for the influence of plasma electron-electron collisions in correlated proton stopping forces. First calculations of the effects of these collisions on the vicinage forces for plasma matter are shown. In particular, these effects are studied in a Te = 10 eV and n = 1023 cm−3 plasma yielding a self-retarding proton force increased more than 11% at maximum value. Also vicinage forces enhances more than 15% in the analyzed cases. All this implies that plasma electron-electron collisions play an important role both in non and correlated ion stopping and must be considered for any application of ion energy deposition in plasma matter.