Layered-targets experiments at 1.06-μm laser light have been performed in order to measure mass-ablation rate ṁ and ablation pressure Pa as a function of absorbed laser flux Ia and laser wavelength λL at irradiances of 1011-4.5 × 1012 W/cm2. The results can be put in the forms ṁ(g/cm2-s) ≈ 4.25 × 105[Ia(W/cm2)/1014]5/9(1 μm/λL)4/9 and Pa(Mbar) ≈ 20[Ia(W/cm2)/1014]7/9(1 μm/λL)2/9, which are consistent with the estimates obtained from a steady-state self-regulated model for plasma heating and with hydrodynamical simulations. Results show also a small lateral energy transport.

The theoretical description of the energy loss of heavy ions in fully ionized matter is considered, where we focus on the many–body and plasma physics aspects of the stopping of point like projectiles with a fixed charge by free electrons, disregarding the atomic physics of the projectile and the target ions. This starts by identifying different coupling regimes for a heavy ion which passes through an electron plasma, and continues with a discussion of the available and appropriate analytical and numerical treatments of the energy loss and their applicability in these various regimes. Special attention is given to a nonlinear coupling regime with significant strong coupling effects on the projectile-target energy transfer where standard perturbative approaches cease to be valid. More advanced theoretical treatments, which are required for this regime, are presented, discussed and evaluated by comparison with simulation results.

The evolution processes of double-layers have been studied in a series of laboratory experiments using a triple plasma device. It was found that the existence of virtual cathode type potential wells at the electron injection boundary was the dominant triggering mechanism. The rapid growth of the potential well led to collisionless ion trapping and the establishment of the necessary trapped ion population. For double layers with small potential drops, collisionless ion trapping actually induced ion–ion streaming instabilities and the formation of ion phase-space vortices. In this regime, the system often exhibited relaxation type oscillations which corresponded to the disruption and the recovery of the double layers.

Modern experimental methods and instruments for X-ray spectral investigation of hot dense plasma provide complex information on environmental conditions in extreme states of matter. The basic spectroscopic conceptions for K-shell plasma diagnosis are outlined, the main characteristics of toroidally bent crystal spectrometers and vertical-dispersion instruments are briefly reviewed. Selected applications (monitoring and optimization of the emission from the femtosecond-laser-produced plasmas, characterization of colliding laser-exploded foils, spectral line merging, and continuum lowering in constrained-flow plasmas) demonstrate the usefulness of advanced spectroscopic methods for plasma diagnostics and fundamental research.

A practical, visible nuclear-pumped laser (NPL) has been sought at the University of Illinois and other laboratories for a number of years. Yet, the results from successful visible NPLs to date have not been fully satisfactory, e.g., the threshold pumping power is too high for conventional applications. Progress in recent studies of 3He-Ne-H2 as a candidate NPL operating in the visible region at 585.3 nm on the 2P1,-1S2 Ne transition is described. We obtained lasing on the above transition for 3He-Ne-H2 concentrations of 1,140, 588, and 412 torr, respectively, with the laser cavity placed in the beamport of the University of Illinois TRIGA reactor. The threshold thermal neutron flux is 1014 n/cm2-s, corresponding to a threshold pumping power of 5 W/cm3.

This report presents the overview of the results of investigation of transport properties of warm dense matter in the conditions with strong coupling generated as a result of the shock or multiple shock compression of substance up to the megabar pressure range. We consider the results of measurements of the electrical conductivity in two different regions. The first one is the high temperature region, where the temperatures are of the order or much higher than the ionization potential I of the compressed substance. The region of “pressure ionization” where T ≪ I is the most interesting from the point of view of the specific plasma phase transitions. A few amounts of experimental data on shock compressed matter viscosity are discussed. For the estimations of shear viscosity of strongly coupled plasma experimental data on measurements of electrical conductivity of hydrogen, deuterium and rare gases under intense shock compression were used. It is shown that the ratio of shear viscosity coefficient to volume density of entropy of strongly coupled plasma is of the order of a lower bound, predicted by Kovtun et al. (2005) in frames of string theory methods.

A technique is demonstrated for optimally generating three-dimensional reconstructions of images formed using a minimal quantity of data. The results are illustrated using thermonuclear α-particles from laser-driven implosions. The images are generated with a maximum entropy deconvolution algorithm from sets of three or four penumbral imaging cameras. It is demonstrated that this approach provides superior resolution and reveals structures not visible from the corresponding two-dimensional reconstructions of the constituent data. This technique can be successfully applied even when the total number of particles recorded in the image is less than 1000.

The paper gives graphical and analytical investigation of the effect of critical beam power on self-focusing of cosh-Gaussian laser beams in collisionless magnetized plasma under ponderomotive non-linearity. The standard Akhmanov's parabolic equation approach under Wentzel–Kramers–Brillouin (WKB) and paraxial approximations is employed to investigate the propagation of cosh-Gaussian laser beams in collisionless magnetized plasma. Especially, the concept of numerical intervals and turning points of critical beam power has evolved through graphical analysis of beam-width parameter differential equation of cosh-Gaussian laser beams. The results are discussed in the light of numerical intervals and turning points.

Charge-exchange collisions are one of the effective pumping methods for soft X-ray lasers. Experiments are performed to investigate charge-exchange collisions between highly charged Mg ions in colliding laser-produced magnesium plasmas. Pinhole photography and XUV spectroscopy are used as diagnostic tools. Spectroscopic studies show selective population of n = 3 levels of Mg IX ions, which results in enhancement of respective line intensities. Theoretical calculations also give a large cross section as high as 10−15 cm2 for these charge-exchange collisions when the relative velocities of the colliding ions are of the order of 107 cm s−1. XUV pinhole pictures are taken in early stages, which give more insight into the expansion dynamics of the colliding magnesium plasmas.

In previous works, we developed several atomic physics models for calculating opacities for low-Z materials. In this work, we used those models for obtaining opacities for Au plasmas in local thermodynamic equilibrium. In this particular case, a great number of configurations must be considered for a full treatment of atoms at plasma conditions. Thus, we included several changes in the aforementioned models, which are extensively reported here.

An expression for the stopping power is derived in the quantum T-matrix approximation. The transport cross sections needed for a numerical evaluation are calculated using a scattering phase-shift analysis. Numerical results are given for the stopping power of an electron beam running into an electron gas. The temperature and density dependencies of the stopping power are discussed. Finally, dynamical screening is included in the weak coupling limit according to a kinetic equation proposed by H.A. Gould and H.E. DeWitt.

We obtained the output of single frequency laser pulses with an average pulse-width of 136 ps and the minimum of 123 ps based on stimulated Brillouin scattering pulse compression pumped by an 8 ns-pulse-width, 1064 nm-wavelength Q-switched Nd:YAG laser. The pulse-width stability of the output is about 4.1% while that of the pump pulses is about 1.1%, the highest energy conversion efficiency is about 85%, and the single pulse energy is above 300 mJ.

Inertial Confinement Fusion (ICF) research has been extensively advanced with the increase of the focusable power on target by the development of glass laser technology and its higher harmonic generation (Yamanaka & Kato et al. 1981) and by CO2 lasers (Yamanaka & Nakai et al. 1981) which cover the wavelength range from 10 μm to 0·25 μm and power densities up to 1017 W/cm2. With improved understanding of the implosion in the fuel pellet, breakeven conditions, or ignition, are expected to be achieved within the 1980's with the construction of lasers in the region of 100 kJ and 100 TW output power.

The self-focusing/defocusing of Hermite-sinh-Gaussian (HshG) laser beam in underdense inhomogeneous plasmas is studied by using higher-order approximation theory. It is found that Hermite mode index and the fluctuation of the periodic plasma density have a significant effect on the dielectric constant and laser beam self-focusing/self-defocusing. With the increase of mode index, the high-order HshG laser beam is beneficial to suppress self-focusing and enhance self-defocusing. In addition, the effects of decentered parameters, beam intensity, and plasma non-uniformity on self-focusing/self-defocusing are discussed.

In this paper, a new kind of solid-state Marx generator based on synchronous transformer type magnetic switches (TTMS) is put forward, and the TTMSs with new winding structures are used to substitute all the spark gaps in the traditional Marx generator for the purposes of solidification and long life time. As the new type of TTMS with high step-up ratio and low saturated inductances is employed, the proposed Marx generator becomes a compact combination of pulse transformer, magnetic switch, and Marx capacitors. The stages of the Marx capacitors can be synchronously charged in parallel before the magnetic core saturates, and these Marx capacitors also can synchronously discharge in series. The establishing time of the proposed Marx generator is at ns range. As the new type of self-reset TTMS is used, the input voltage of the Marx generator decreases to a low level less than 1 kV while the output voltage can easily reach a high level ranging from dozens of kV to hundreds of kV.

We report on a setup for the investigation of proton acceleration in the regime of target normal sheath acceleration. The main interest here is to focus on stable laser beam parameters as well as a reliable target setup and diagnostics in order to do extensive and systematic studies on the acceleration mechanism. A motorized target alignment system in combination with large target mounts allows for up to 340 shots with high repetition rate without breaking the vacuum. This performance is used to conduct experiments with a split mirror setup exploring the effect of spatial and temporal separation between the pulses on the acceleration mechanism and on the resulting proton beam.

Small conical targets have been used in high intensity laser target interaction mostly in the context of fast ignition. We demonstrate that when cone targets are shaped appropriately and used with specific interaction conditions, they can produce particle beams of higher maximum energy and number in a lower angular divergence than flat targets. This is relevant to fast ignition, small compact particle beams, medical applications, focused ion and/or electron beam microscopes. This fact carries the potential to produce particle beams that are no longer limited by the characteristics of the laser. Note that for fast ignition, reducing the divergence of the beam lowers the energy requirement and enhances the energy deposition into the compressed fuel.

We study the interaction of an ultra-high intensity laser pulse with plastic flat-top cone targets with curved walls and cone targets with straight walls. We find the appropriate type, dimensions of the cone target, and the ultra-high intensity laser pulse parameters for which the accelerated ions have the maximum energy and their number is the highest for a lower angular divergence and a better laser absorption. This numerical study will allow one to prepare and optimize first laser-ion acceleration experiments on CETAL using micro-cone targets.

To determine the peak pressure induced versus the incident intensity of a neodymium (Nd) glass pulsed laser, with a duration of 25 ns in glass confined geometry, two methods have been comparatively used. Free surface velocity measurements have been performed using an electromagnetic gauge. The results are compared with pressure measurements realized at the back of irradiated aluminum targets with the use of polyvinylidene fluoride (PVDF) gauges. Both diagnostics provide consistent results. The measurements of peak pressure as a function of laser irradiance are used to determine the calibration curve (current density versus loading pressure) for new VF2/VF3 copolymer shock gauges used in this lasermatter interaction configuration. These experimental set-up deliver time resolved measurements that are interpreted by the shock-propagation phenomena.