We describe the mathematical basis and organization of Crunch, a ID shock-hydrodynamics code to analyze pulsed-power experiments at Los Alamos National Laboratory. The program uses finite-element methods that preserve stability during material collisions and shock convergence on axis. It handles coupled calculations of nonlinear magnetic diffusion to simulate imploding liners. These calculations may be driven by multiple current waveforms or a selfconsistent current variation derived from a pulsed-power generator model. Crunch incorporates elastic material contributions and calculates element break and melt points. The primary goal in program development was effective use by experimentalists. Crunch is controlled by a streamlined script language and runs on standard personal computers. An interactive graphical postprocessor expedites analysis of results. To support the program we have assembled data resources in machine-independent format including Sesame equation-of-state tables, a material strength library and a library of temperature-dependent conductivities.

Some characteristics of the picosecond laser produced plasma expanding across an externally applied magnetic field (0.6T) have been reported. Two to three times enhancement in X-ray emission from copper plasma has been observed for the laser intensity range ∼5 X 1011 to 5 X 1012 W/cm2. The X-ray yield has been found to increase with an increase in the magnetic field intensity. Enhancement in X-ray emission is correlated with confinement of expanding plasma either in external magnetic field or in high ambient gas pressure. Generation of some highfrequency instability and fast ions was also observed in the plasma along with bouncing of plasma near the β = 1 surface where kinetic pressure of plasma equals magnetic pressure.

The results of a high-resolution processing, based on techniques of fractal dimension analysis, of experimental data from earlier experiments on the linear Z-pinches are presented, which prove the electric current-carrying plasmas to be a random fractal medium. The basic building block of this medium is identified to be an almost-closed helical filamentary magnetoplasma configuration (we call it heteromac). The heteromacs are coupled together through long-range self-sustained filamentation and, thus, form a dynamical percolating network with dissipation. The results (i) extend recently identified phenomenon of the 3D large-scale (up to several centimeter size) helical filamentary plasma structures (Kukushkin et al. 1994, 1995, 1997a) in plasma focus gaseous discharges to the case of Z-pinch gaseous discharges and (ii) provide a novel view into the dynamics of Z-pinch's necks, plasma spikes, and magnetic bubbles as well as into generic features of electric current-carrying plasmas varying from low-electric current laboratory plasmas to cosmic plasmas. This covers about 30 orders of magnitude of length scale and suggests unprecedented opportunities for interpolating between and extrapolating from well-understood phenomena. A magnetoplasma universe model is suggested.

Analytic analysis of collisionless Weibel modes in laser-created plasmas is presented. The heat flux (HF), the plasma expansion (PE), and the inverse bremsstrahlung absorption (IBA) sources have been investigated. It has been shown that for short laser wavelengths (λL < 1 µm) and high laser fluxes (I > 1014 W/cm2), the inverse bremsstrahlung absorption is the most efficient Weibel mechanism for producing strong magnetic fields in the vicinity of the critical layer. For large laser wavelengths (λL < 10 µm), the production of the magnetic fields in the vicinity of the critical layer, due to the plasma expansion mechanism, is as important as the ones due to the thermal transport and the inverse bremsstrahlung absorption mechanisms. Useful scaling laws of convective e-foldings, with respect to the laser and the plasma parameters, are also derived.

Laser plasma experiments reveal rich interplay between laser plasma instabilities. The growth of stimulated Brillouin scattering (SBS) is one of the most significant constraints of laser fusion experiments. In this paper, a mechanism of stabilization of SBS process due to magnetic anisotropy has been presented. Magnetic anisotropy induced by the temporally exponentially growing nonoscillating magnetic moment from inverse Faraday effect (IFE) has been studied.It has been shown that for interaction of Nd laser (λ = 1.06 μm) on solid deuterium target the SBS growth rate (y) ∼ 3.45 ps and the phase velocities of the incident and scattered electromagnetic (EM) waves have been shown to decay exponentially (∼e∼λ1) in this SBS process resulting in wave-number mismatch.

The acceleration of transparent charged macroparticles by the repeated radiation pressure of a laser beam is considered. A radial electric field allows a motion along a closed path, on a stable orbit. For macroparticles made out of carborundum, of radius r = 0.5 μm, velocities above 100 km/s look feasible, allowing the production of high densities of energy.

The concept and experimental results of a microwave-excited elliptical excimer lamp are presented in this paper. The plasma excimer photons are excited at one focus, and the absorber is placed at the second focus. Two elliptical microwave cavities with different eccentricities were tested to study the excitation and characteristics of such an elliptical excimer lamp. The results show that it can be a high-efficiency, narrow-band incoherent vacuum–ultraviolet (VUV)-to-near-infrared photon source. The potential applications of such an excimer lamp, especially with tunable vibronic solid-state and diamond thin film growth, are discussed.

The properties of heavy-ion induced fusion targets with two-sided illumination and with the converters placed completely inside the Hohlraum have been investigated using integrated simulations based on the SATURN and MIMOZA code packages in order to check the results obtained with the view-factor method in previous work, which is briefly reviewed. Separate converter simulations show the importance of an accurate treatment of radiation transport but also demonstrate that a converter efficiency of 40–80% can be achieved easily depending on the detailed converter material and geometry. For the complete target, a gas fill is shown to be necessary, and it turned out to be very important to allow some of the radiation shields to become partially transparent during the evolution. In the most favorable case, an asymmetry in the temperature on the capsule of about 5% was achieved, leading to a reduction of the neutron yield by a factor of 7 compared to an ideally symmetric situation.