In this paper, we want to discuss different hydrodynamic schemes for fast ignition and some of their basic effects. Relativistic hydrodynamics and a covariant generalized Ohm's law are presented. Matter perforation (hole boring) by an intense laser pulse is investigated by 2D numerical simulations and a simple formula for the perforation speed is derived. Furthermore, we study macroparticle acceleration by an intense laser beam and the possibility to provide an energetic and massive projectile for ballistic ignition. The dynamics of ignition of a precompressed D–T mixture is illustrated by numerical simulations in planar 2D geometry using direct laser irradiation and macroparticle impact as external drivers. Electron heat conduction is found to be responsible for an efficient burn wave propagation which prevents the hot gas bubble of burning fuel from deflagrating into vacuum.

In this paper, the characteristic impedance matching of the inner line and outer line of the multi-filar tape-helix Blumlein pulse forming line (BPFL) is analyzed in detail by dispersion theory of tape helix. Analysis of the spatial harmonics of multi-filar tape-helix BPFL shows that the integer harmonic numbers of the excited spatial harmonics are not continuous. In addition, the basic harmonic component still dominates the dispersion characteristics of the multi-filar tape-helix BPFL at low frequency band. The impedance mismatching phenomenon caused by the discontinuity of filling dielectrics in the inner line of BPFL is studied as an important issue. Effects of dielectric discontinuity on the coupled electromagnetic fields and the parameters of the outer line are also analyzed. The impedance matching conditions are both obtained under the situations of continuous filling dielectric and discontinuous dielectrics, respectively. Impedance characteristics of these two situations are analyzed by comparison, and effects of the thickness of support dielectric on the impedance are also presented. When the 6 mm-thickness nylon support of the multi-filar tape helix is used in the filling dielectric of de-ionized water, the characteristic impedances of the inner line and outer line of BPFL are 53 Ω and 14.7 Ω, respectively. After the improvement about substituting de-ionized water by castor oil, the relative permittivities of the support dielectric and filling dielectric are almost the same, and the impedances of the inner and outer line of BPFL become 80 Ω and 79 Ω, respectively. That is to say, the impedance mismatching problem caused by dielectric discontinuity is solved. Circuit simulation and experimental results basically correspond to the theoretical results, and the fact demonstrates that impedance analysis of the multi-filar tape-helix BPFL based on dispersion theory is correct.

A formalism for investigation of the propagation characteristics of various order short duration (pico second) Gaussian/dark hollow Gaussian laser pulse (DHGP) in a tunnel ionized plasma has been developed, which takes into account the electron-ion recombination. Utilizing the paraxial like approach, a nonlinear Schrödinger wave equation characterizing the beam spot size in space and time has been derived and solved numerically to investigate the transverse focusing (in space) and longitudinal compression (in time) of the laser pulse; the associated energy localization as the pulse advances in the plasma has also been analyzed. It is seen that in the absence of recombination the DHGP and Gaussian pulse undergo oscillatory and steady defocusing respectively. With the inclusion of recombination, the DHGP and Gaussian pulse both undergo periodic self-focusing for specific parameters. The DHGPs promise to be suitable for enhancement of energy transport inside the plasma.

In this paper we present measurements of energy transport in hot, high-density plasmas produced by picosecond laser interaction with solid targets. The propagation of the ablative heat wave was studied by using X-ray-ultraviolet (XUV) spectroscopy with picosecond temporal resolution. Measurements show that for laser intensities on target above 1016 W/cm2, strong inhibition of heat flux toward the cold target occurs. A detailed modelling of the experimental data is presented in which heat transport and absorption processes are taken into account self-consistently. Finally the role played by lateral transport and self-induced magnetic fields in our experiment is also discussed.

We present results from non-LTE line radiation transport calculations for high-temperature, optically thick plasmas with densities ∼1016-1020 ions/cm3. The calculations are based on an escape probability radiative transport model in which the atomic rate equations are solved self-consistently with the radiation field. Steady-state ionization and excitation populations are determined by detailed balancing of atomic processes, with photoexcitation effects included. Atomic data are computed using a combination of Hartree-Fock, semiclassical impact-parameter, and distorted-wave calculations. Our results indicate that the reabsorption of line radiation significantly alters the level populations and reduces the radiation flux from several types of fusion-related plasmas. We also compare our results with those obtained from multigroup radiation diffusion calculations, and discuss the ramifications of our results for ICF target chamber plasmas.

A laser transmission experiment is conducted to examine atmospheric turbulence-induced angle-of-arrival fluctuations over an 11.8 km urban path. The variance of fluctuations, probability density function, power spectrum, and Fried coherence length are investigated based on the analysis of the experimental data collected in each season of a year, respectively. In addition, the daily variations characteristic of path-averaged optical turbulence intensity Cn2 is also studied. At last, the aperture averaging theory is validated. It is anticipated that this work is helpful to the research of optical wave atmospheric propagation and the design of free-space laser optics communication systems.

Advances in laser and Z-pinch technology, coupled with the development of plasma diagnostics, and the availability of high-performance computers, have recently stimulated the growth of high-energy density laboratory astrophysics. In particular, a number of experiments have been designed to study radiative shocks and jets with the aim of shedding new light on physical processes linked to the ejection and accretion of mass by newly born stars. Although general scaling laws are powerful tools to link laboratory experiments with astrophysical plasmas, the phenomena modeled are often too complicated for simple scaling to remain relevant. Nevertheless, the experiments can still give important insights into the physics of astrophysical systems and can be used to provide the basic experimental validation of numerical simulations in regimes of interest to astrophysics. We will illustrate the possible links between laboratory experiments, numerical simulations, and astrophysics in the context of stellar jets. First we will discuss the propagation of stellar jets in a cross-moving interstellar medium and the scaling to Z-pinch produced jets. Our second example focuses on slab-jets produced at the Prague Asterix Laser System laser installation and their practical applications to astrophysics. Finally, we illustrate the limitations of scaling for radiative shocks, which are found at the head of the most rapid stellar jets.

The diode closure velocity has been investigated in pulsed high-power diodes operating with the mode of space-charge-limed bipolar flow. A combination of time-resolved electrical and optical diagnostics has been employed to study the basic phenomenon of the temporal and spatial evolutions of the diode plasmas. The results from the two diagnostics were compared. Since anode plasma rapidly expands, the diode closure speed vd increases in the end of the current pulse. The diode closure speed vd can be divided into three stages with a U-like whole shape. The obtained results can be used in various applications, for instance, the high-power microwave sources, electron-beam plasma heating, and material treating.

This work reports a comparative study of laser ion implantation mainly performed at the Nuclear Physics Institute in Rez (Czech Republic), National Institute of Nuclear Physics (Italy), and the Plasma Physics Laboratory at the University of Messina (Italy) using different approaches. Thick metallic targets were irradiated in vacuum by a focused laser beam to generate plasma-producing multi-energy and multi-species ions. A post-acceleration system was employed in order to increase the energy of the produced ions and to generate ion beams suitable to be implanted in different substrates. The ion dose was controlled by the laser repetition rate and the time of irradiation. Rutherford backscattering analysis was carried out to evaluate the integral amount of implanted ion species, the concentration–depth profiles, the ion penetration depth, and the uniformity of depth profiles for ions laser implanted into monocrystalline substrates. The laser implantation under normal conditions and in post-acceleration configuration will be discussed on the basis of the characterization of the implanted substrates.

In this study, an atmospheric pressure dielectric barrier discharge-based argon plasma jet has been modeled using COMSOL Multiphysics, which is based on the finite element method. The fluid dynamics and plasma modules of COMSOL Multiphysics code have been used for the modeling of the plasma jet. The plasma parameters, such as electron density, electron temperature, and electrical potential, have been examined by varying the electrical parameters, that is, supply voltage and supply frequency for both cases of static and with the flow of argon gas. The argon gas flow rate was fixed at 1 l/min. Ring electrode arrangement is subjected to a range of supply frequencies (10–25 kHz) and supply voltages (3.5–6 kV). The experimental results of the ring electrode configuration have been compared with the simulation analysis results. These results help in establishing an optimized operating range of the dielectric barrier discharge-based cold plasma jet in the glow discharge regime without arcing phenomenon. For the applied voltage and supply frequency parameters examined in this work, the discharge was found to be consistently homogeneous and displayed the characteristics of atmospheric pressure glow discharge.

Radiation-induced conductivity (RIC) is a generalized term for photoconductivity expanded to include nonelectromagnetic radiation. RIC offers several distinct advantages for the detection of high-energy radiation: (i) the speed of response of a detector is determined by a bulk property of the material, the carrier lifetime; (ii) the detector can be directly illuminated by the signal radiation-no dead layer; and (iii) the selection of the detector material and its geometry is very flexible. This paper will discuss the principles of RIC for X rays and neutrons, the fabrication of detectors, and applications. RIC detectors have been fabricated from Si, InP, GaAs, and diamond. Bulk and thin film materials have been used. The carrier lifetime was varied by the introduction of trapping sites in the material. This can be done in the material production process in the case of doping (e.g., Fe in InP) and thin films or produced from radiation damage of a pure crystalline material. Lifetimes as short as a few picoseconds have been observed. A variety of detectors have been tested using pulsed optical, X ray, and neutron sources. Absolute sensitivities and temporal response has been measured and compared to theoretical models of the detector's performance for both X rays and neutrons. Finally, applications of these detectors to inertial confinement fusion measurement will be shown.

A diffusion technique most commonly used for filling targets with a gas fuel. The need to minimize the tritium inventory in the fill station and to decrease the radiation damage during the fill raises a question of its thorough analyses to determine an efficient pressurization scheme for single and multilayer polymer shells. In this report, we present the results obtained in this area.

Space observations have opened the spectral regions of X-rays and γ-rays, which are produced by plasma processes. The Plasma Universe derived from observations in these regions is drastically different from the now generally accepted ‘Visual Light Universe’ based on visual light observations alone. Historically this transition can be compared only to the transition from the the geocentric to the heliocentric cosmology.

The purpose of this paper is to discuss what criteria a cosmological theory must satisfy in order to be acceptable in the Plasma Universe.

We present a three-dimensional code for the optimization of energy storage, heat deposition, and amplification in square-shaped laser slabs and multi-slab laser amplifiers. The influence of the slab dimensions, slab face and edge reflectivities, pump parameters, and operating temperature on amplified spontaneous emission and stored energy has been investigated. The multi-slab and single-slab configurations are compared, analyzing in detail the influence of the absorption cladding for the suppression of amplified spontaneous emission radiation.

The first harmonics beam generated by an iodine laser system was focused by an f/2 optics on an Al foil target. The X-ray output from the laser plasma both in the line and broad-band spectra was registered over an interval around the “ideal” focus. It was found that the maximum X-ray power is not obtained in the focus itself but for a somewhat larger focal spot outside the focus. To explain this phenomena, temperature and density measurements were in addition made. The plasma temperature evaluated from both the line (He-like Al XII resonant line and j, k, l satellites) and broad-band spectra (two foil method) was also measured and found to be largely constant in the vicinity of the focus. The line and broad-band temperatures differ, the broad-band temperature being about 25% higher. The electron density was equally determined using an intercombination line.

The conversion of kinetic energy into heat is a possible approach to get the very high temperatures needed for controlled fusion. Various techniques leading to hypervelocities are considered. Some particular geometries and constitutions of liners allowing velocity amplification and superheating are described.

Recent experiments undertaken at the Rutherford Appleton Laboratory to produce X-ray lasing over the 5–30 nm wavelength range are reviewed. The efficiency of lasing is optimized when the main pumping pulse interacts with a preformed plasma. Experiments using double 75-ps pulses and picosecond pulses superimposed on 300-ps background pulses are described. The use of travelling wave pumping with the approximately picosecond pulse experiments is necessary as the gain duration becomes comparable to the time for the X-ray laser pulse to propagate along the target length. Results from a model taking account of laser saturation and deviations from the speed of light c of the travelling wave and X-ray laser group velocity are presented. We show that X-ray laser pulses as short as 2–3 ps can be produced with optical pumping pulses of ≈1-ps.

One of the features of ultra high intensity (UHI) short pulse laser–matter interactions is the prospect of creating a cheap, compact source of hard X rays with femtosecond pulse duration. The properties of such Kα sources are studied using analytical and numerical models of hot electron generation and subsequent transport in a range of materials (Reich et al., 2000). First, we find that there is an optimum laser intensity for Kα generation from bulk targets, which scales as Z4.4. Second, we show that efficient hard X-ray pulses with durations below 100 fs can be generated at intensities of ∼1016 W/cm2.

A novel method of utilizing fluorescence generated from the products of nuclear reactions offers the prospect of compact, high efficiency, multi-megajoule lasers. To overcome the problems associated with traditional laser (or energy converter)-fissile material interfaces, such as a uranium coating (low power density and low efficiency) or a gaseous uranium compound (low power density and deleterious effects on the laser kinetics and photon transport), a method suggested elsewhere of employing a reactor using a uranium aerosol fuel, interspersed with a fluorescer medium, is briefly reviewed. The charged particles produced by nuclear reactions in the fuel produce fluorescence in the core region of the reactor, through interactions with the fluorescer. This fluorescence can then be concentrated, to increase the effective power density in the laser medium, and used to drive a photolytic laser.

One key issue in the above process is the charged particle spectrum from the fissile aerosol. These issues can be addressed theoretically based on the Dirac chord length distribution technique and an Arcen's function. The charged particle spectrum from a UO2 coating has been generated and benchmarked with the experimental data of Kahn et al., and Redmond et al. Agreement is generally good except near the end of the fission fragment tracks. The validity of this simple technique in approximating the rate of ion energy loss lends confidence to the generation of fission fragment spectra for other geometries (i.e. spherical in which transport efficiencies of over 60% appear achievable) using U, UO2 and U3O8. Work is also extended to the case of B-10 in a variety of configurations which are frequently used in modern energy conversion experimental devices.

Vertical dispersion variant of the double-crystal spectrograph is analyzed and its basic quantitative characteristics (luminosity, resolving power) are computed using ray tracing code. It is shown that geometric apparatus smearing is minimized due to high dispersion and spectral resolution may considerably exceed the single-crystal diffraction limit. Performing high-resolution spectral work, the efficiency of the double-crystal apparatus exceeds that of the flat single-crystal spectrograph. The usefulness of this method in laser plasma spectroscopy is demonstrated analyzing the detection of phosphorus He-like resonance line and its satellites.