In this article, the results of experimental and numerical studies of the behavior of perturbed interface between air and helium are presented. The interface is initially accelerated by the incident shock wave coming from air to helium and then decelerated by a series of reflected shock waves. Two types of initial interface perturbations like “saw” and “step” are considered.

The investigations of the influence of various types of wavefront distortions, varying in time, on the intensity distribution on the surface of a target are carried out. It is shown that distortions of a wavefront, equivalent to transverse displacement in time of a beam in far field at an angle of approximately 10 diffraction angles, results in practically full smoothing of a specl-structure of intensity distribution. Creation of phase distortions of a beam assigned as running in a cross section wave with an amplitude of more than 3 radian and with a spatial size exceeding 20–30 times the size of the kinoform phase plate element, permits us to reduce the depth of modulation in distribution of intensity in far field also. The capability of application is considered as a smoothing device of the dynamic plasma layer, based on the volume-structured medium. The model of energy transport process in such media is developed. Matching of calculation and experimental results is conducted.

Spherical gold Hohlraums were heated by the iodine laser ASTERIX IV (200 J/0.4 ns at 440 nm) and were used to investigate radiative heating of low-Z plastic foils at temperatures up to 100 eV by time-resolved XUV emission and absorption spectroscopy. Spectra of the reemitted radiation (the albedo) for different C-, O-, F-, or Cl-containing plastic materials are presented. Depending on the material, the typical total (frequency-integrated) reemission is in the range of ≈10% of the gold reemission. By measuring the absorption spectra it was possible to follow the burnthrough in carbon from the initial solid degenerate state up to a high ionization state with absorption lines due to hydrogen-like carbon corresponding to a temperature of about 100 eV. The propagation of the heat wave into the material also has been studied by observing the emission from boron tracer layers embedded at different depths in the plastic foil. The experimental observations are compared with MULTI simulations.

The emissions to the atmosphere, by a heavy ion inertial fusion reactor in accidental and normal operations, are in form of tritium gas with two chemicals forms of tritium: HT and HTO. Emissions of 100% HT have been analyzed in this work, and their consequences in the dosimetry. The primary phase of the emission depends on the atmospheric conditions. As a consequence, the tritium is dispersed far from the source. The HT can be oxidized in the stratosphere or in the surface by microbiological action to convert it to HTO, and back to the air in a reemission process or penetrate into the subground. In the form of HT, the effective dose equivalent (EDE) is important in the case of intake (inhalation, skin absorption, or ingestion), because tritium is a beta emitter of low energy and the dose by external uptake is not considerable. Thus, the dose by ingestion contributes the most to the total dose in the case of HT rather than HTO. It constitutes 98% of the total EDE, in contrast with the contribution to the total dose by HTO, which is only 40%.

In the present paper, measurement of various plasma parameters during pulsed laser deposition of ruby thin film on quartz substrate is reported. The variation of electron temperature and ion density with laser fluence and ambient pressure is recorded via Langmuir probe technique. The structural and optical properties of ruby thin films were analyzed using photo-luminescence and atomic force microscopy, and then correlated with the plasma parameters to find optimum conditions for deposition of high quality ruby thin film.

The target chamber of an inertial confinement fusion (ICF) power plant or high-yield test facility must be designed to absorb the target produced Xrays and ions and survive the resulting effects. The target chamber conditions must be restored in fractions of a second for high repetition rate power applications. Computer modeling of these phenomena is essential because equivalent conditions cannot be produced in laboratory experiments prior to the first ignition of high-yield ICF targets. Choices of models are dictated by specific reactor design strategies. The two major strategies, gas protection and sacrificial first surfaces, are used as a guide to our discussion. Physical models for ion, electron, and X-ray deposition are discussed, along with physical and numerical modeling of the resulting phase changes intarget chamber structures. The hydrodynamics and radiative transfer in the target chamber vapors and plasmas are central topics.

This paper presents the results of theoretical and experimental studies on high-pressure He-Cd and He-Zn lasers. It is shown that using the hard ionizer approximation makes it possible to readily and efficiently simulate the plasma chemical processes that occur in the active media of high-pressure lasers pumped by electron and ion beams as well as by nuclear reaction products in electron-beam experiments. Laser oscillation was achieved at λ = 325, 441.6, 533.7, and 537.8 nm for the cadmium ion and at λ = 610.3 nm for the zinc ion.

Z pinches have long been interesting to plasma physicists because of the simplicity of their geometry. They were studied first in the 1950s as potential fusion configurations and, later, as intense X-ray sources both for military and civilian applications. The development of pulsed power technologies, some reaching energy and power levels of 3 MJ and 50 TW, respectively, by many organizations around the world has accelerated the interest in z pinches for fusion applications.

The present measurements of the components' surface resistance to laser-induced damage has been completed to facilitate development and construction of the “Luch” laser system, a four-channel Nd-phosphate glass laser with a full output energy of E = 14–16 kJ. The study describes a method that, with a series of experimental data obtained from a single sample, allows us not only to estimate the threshold fluences, but to take into account the statistical nature of the surface damage. In a number of experimental situations this method makes it possible to estimate damaging fluences even from the result of a single exposure of the studied surface. Estimated threshold fluences for various optical elements are presented: K8 glass, experimental phosphate laser glass KGSS-0180, high-reflecting and antireflecting thin-film coating of elements. The 1.054-μm radiation pulse with half-height duration of 4 ns and the irradiation spot of ∼4 mm in diameter were used in the experiment.

The third harmonic generation of a self organized nonlinear laser Eigen mode of a two-dimensional plasma channel with complete electron evacuation from the inner region is investigated. The nonlinearities arise through the ponderomotive force and relativistic mass variations, while the ions are taken to be immobile. The second harmonic ponderomotive force produces electron density oscillations that beat with the oscillatory velocity due to the laser Eigen mode to create a nonlinear current, driving the third harmonic. As a0 increases up to the threshold value amin, at which complete electron evacuation begins in the inner region, the third harmonic amplitude rises rapidly. Above the threshold, as a0 increases, the width of the inner region where there is no third harmonic current, increases and third harmonic amplitude rises less rapidly. The conversion efficiency is found to be in reasonable agreement with the experimental results.

A one-dimensional, time-dependent fluid code is presented that numerically solves the hydrodynamic equations together with the wave equation for a picosecond pulse laser heated plasma. The laser light absorption by classical inverse bremsstrahlung and the ponderomotive force are evaluated self-consistently from the computed electromagnetic field quantities. At oblique incidence of p-polarized 1·054 μm laser radiation the resonant electric field is saturated by plasma wave convection through the nonlinear density profile steepening prior to wave breaking.

Proton radiography is used for advanced hydrotesting as a new type radiography technology due to its powerful penetration capability and high detection efficiency. A new proton radiography terminal will be developed to radiograph static samples at the Institute of Modern Physics of Chinese Academy of Science. The proton beam with the maximum energy of 2.6 GeV will be produced by Heavy Ion Research Facility in Lanzhou-Cooling Storage Ring. The proton radiography terminal consists of the matching magnetic lens and the Zumbro lens system. In this paper, the design scheme and all optic parameters of this beam terminal for 2.6 GeV proton energy are presented by simulating the beam optics using WINAGILE code. My-BOC code is used to test the particle tracking of proton radiography beam line. Geant4 and G4beamline codes are used for simulating the proton radiography system. The results show that the transmission efficiency of proton without target is 100%, and the effect of secondary particles can be neglected. To test this proton radiography system, the proton images for an aluminum plate sample with two rectangular orifices and a step brass plate sample are respectively simulated using Geant4 code. The results show that the best spatial resolution is about 36 μm, and the differences of the thickness are not >10%.

Experiments were performed using high-power laser pulses (greater than 50 TW) focused into underdense helium, neon, or deuterium plasmas (ne ≤ 5 × 1019 cm−3). Ions having energies greater than 300 keV were measured to be produced primarily at 90° to the axis of laser propagation. Ion energies greater than 6 MeV were recorded from interactions with neon. Spatially resolved pinhole images of the ion emission were also obtained and were used to estimate the intensity of the focused radiation in the interaction region.

We considered an ignition strategy based on energy injection in the final stages of the target implosion, but well before stagnation. The injected energy is used to set on a high adiabat the small portion of the fuel destined to become the ignition spark. Most of the energy needed to form the spark is provided by the work of the imploding target on the spark fuel. This approach is first introduced by a simple analytical model and then illustrated by 2D numerical calculations, in which the ignition of imploding cylinders by heavy ions is simulated. Different implosion designs and burn modes are presented and discussed. When compared with the standard central self-generated spark, or the fast ignition approaches, the ignition by entropy injection is potentially promising of some distinct advantages.

The effect of surface finish on the evolution of ICF targets has been studied. As driver for the implosion has been used a temporally profiled thermal radiation pulse (25 ns in duration) as that expected for the case of a high-gain (cm sized) capsule enclosed in a cavity. 2-D numerical simulations have been performed on a planar analog to investigate the stability to perturbations having wavelengths in the interval 2.5–40 μm and initial amplitudes of 0.03 and 1 μm. The simulations show perturbation growing due to hydrodynamic instabilities. The distortion of the ablation front reaches such a level to strongly enhance the ablation rate because of the increase in the exposed area and in the power absorbed per unit area. Two different phenomena have been identified: one, preferentially occurring for small wavelengths, in which the motion behind the first shock wave becomes turbulent and the symmetry is lost; the other, appearing for long wavelengths, in which a thermal radiation wave penetrates into the fuel. This preheating phenomenon is related to the formation of holes in the thermal shield due to the enhanced ablation and to matter transverse piling up. All these effects may render useless the 1-D-based design of a high-gain capsule exposed to a given thermal bath. However, it has been also observed that, for the longer wavelength (40 μm) and a smaller initial perturbation amplitude (e.g. 0.01 μm), during the temperature pulse the preheating does not occur and most of the fuel can be accelerated as a whole to speeds of the order of 2 × 107 cm/s or greater without a substantial onset of transverse velocities, even in the presence of the ablator piling up.

Effective suppression of transverse stimulated Raman scattering (TSRS) in a large-aperture potassium dihydrogen phosphate (KDP) crystal is an important scientific and technical problem in high-intensity laser research and applications. In this work, a method to suppress TSRS using pulse stacking is proposed. The method suppresses TSRS significantly, with greater numbers of subpulses producing more obvious suppression effects, and the threshold intensity growth rate of the 3ω laser in the KDP crystal reaches up to about 1.9 when the stacked pulse contains four subpulses. This suppression effect is attributed to the fact that the polarization directions of adjacent subpulses are perpendicular to each other. The method can be used to suppress other nonlinear effects, including transverse stimulated Brillouin scattering in large-aperture optical devices and stimulated rotational Raman scattering in long air paths.

Experimental investigations of laser-produced plasma expansion in a strong (−20 T) magnetic field have been carried out. The image and spectra of the plasma flame in the soft X-ray spectral region have been obtained. It has been shown that the strong magnetic field limits the transverse plasma expansion and strongly effects the ion-level populations.

Recent computer experiments on liquid Mg and Bi (and also on dense hydrogen) have focussed anew on issues involving static and dynamical structure in plasmas. In Mg and Bi, under normal liquid metal conditions, separation of core and valence electrons is valuable both for thermodynamics and in interpreting diffraction experiments. Mg is considered in some detail as a specific example where there is weak electron–ion interaction. Finally, dynamical structure is considered. After a brief summary relating back to the electron–electron pair correlation contribution in X-ray scattering, attention is next focussed on the (longitudinal) viscosity of alkali metals via the Kubo formula. This viscosity is shown to be dominated by ion–ion interactions. Nevertheless, an intimate relation at the melting point is exposed between shear viscosity, thermal conductivity, and electrical resistivity, the latter two transport coefficients being dominated by electrons.

A critical test of direct-drive laser-fusion has been conducted with the demonstration of DT compression to densities in the range of 100–200 times liquid density in experiments on the University of Rochester's OMEGA laser facility. The high-density cyrogenic experiments used 351-nm laser pulses with energies of 1500–1800 J and pulse widths in the range of 600–700 ps.

It is shown that beyond a virtual cathode the current of a magnetized steady-state thin annular electron beam in a drift tube may range from zero to the limiting current of the tube.