In this paper, we present a simple annealing procedure (which we refer to as ''flash-annealing'' because of short duration) that results in the formation of an ultralow friction surface film on vanadium diboride (VB{sub 2}) surfaces. This annealing is done in a box furnace at 800 C for a period of 5 min. During annealing, the exposed surface of the VB{sub 2} undergoes oxidation and forms a layer of boron oxide (B{sub 2}O{sub 3}). In open air, the B{sub 2}O{sub 3} layer reacts spontaneously with moisture and forms a boric acid (H{sub 3}BO{sub 3}) film. The friction coefficient of a 440C steel pin against this H{sub 3}BO{sub 3} film is {approx}0.05, compared to 0.8 against the as-received VB{sub 2}. Based on Raman spectroscopy and electron microscopy studies, we elucidate the ultralow friction mechanism of the flash-annealed VB{sub 2} surfaces.

Recent advances in Nd-doped phosphate laser glasses for high-peak-power and high-average-power applications are reviewed. Compositional studies have progressed to the point that glasses can be tailored to have specific properties for specific applications. Non-radiative relaxation effects can be accurately modeled and empirical expressions have been developed to evaluate both intrinsic (structural) and extrinsic (contamination induced) relaxation effects. Losses due to surface scattering and bulk glass absorption have been carefully measured and can be accurately predicted. Improvements in processing have lead to high damage threshold (e.g. Pt inclusion free) and high thermal shock resistant glasses with improved edge claddings. High optical quality pieces up to 79 x 45 x 4cm{sup 3} have been made and methods for continuous melting laser glass are under development.

NIF will be configured in its baseline design to achieve ignition and gain using the indirect drive approach. However, the requirements require the design to not preclude the conduct of inertial confinement fusion experiments using direct drive. This involves symmetrical illumination of an ICF capsule, where each beam fully subtends the capsule. The re-directing of 24 of the 48 NIF beamlines (2x2 beamlet group each) from 30 and 50{degree} cone angles to 75{degree} cone angles near the chamber `equator` is required. This would be done by adjusting intermediate transport mirrors so that the beams intercept different final mirrors in the Target Bay and be directed into final optics assemblies attached to chamber ports positioned at the new port locations. Space for converting from one irradiation scheme to another is a problem; also NIF user needs cannot be compromised by direct drive needs. Target for direct drive, absent a hohlraum, emits much fewer cold x rays than for indirect drive. Further, the irradiation scheme may not result in the absorption of all the 3{omega} light and this may create a hazard to the NIF chamber first wall. This paper describes possible design features of the NIF Target Area to allow conversion …

We have exposed CR-39 track recording material to a number of NOVA implosions. Radiation from the implosion passed through an array of ranging filters, which aided identification of the incident particles and their energies. The etching procedure was calibrated by including a piece of track exposed to DD protons from a small accelerator. For the same shots, we quantitatively compare the DD neutron yield with the DD proton yield determined from the track. In DT implosions, tracks produced by neutron interactions prevent observation of charged-particle tracks that are produced by the processes of knock-on, secondary or tertiary fusion.

Many of the storage tanks with waste from processing fissile materials contain, along with the fissile material, metals which may serve as nuclear criticality poisons. It would be advantageous to the criticality evaluation of these wastes if it can be demonstrated that the poisons remain with the fissile materials and if an always safe poison-to-fissile ratio can be established. The first task, demonstrating that the materials stay together, is the job of the chemist, the second, demonstrating an always safe ratio, is the job of the physicist. The latter task is the object of this paper

NIF is being configured so as to not preclude conduct of radiation experiments that will contribute to evaluating the readiness of military systems and components to withstand radiation environments. The range of possible experimental environments and the flexibility to introduce various types of experimental packages suggests synergism with experiments related to Inertial Fusion Energy development on NIF. Design status of NIF features to support radiation experiments is described, and a relationship to their applicability to IFE experimentation on NIF is discussed.

High-Z, laser heated hohlraums can be made thick enough to contain thermal radiation, yet thin enough to let out x-rays >{approximately}6keV produced by hot, relatively dense blow-off plasma. The authors use such ``thin wall hohlraums`` to observe the physical location of hot, dense, laser produced hohlraum plasmas. This technique has allowed them to come to some understanding of laser transport/deposition, plasma stagnation and bulk plasma filling.

Experiments were performed on Nova at Lawrence Livermore National Laboratory to study the ablation and condensation process of National Ignition Facility (NIF) first wall materials. Plates of candidate first wall materials (SiO{sub 2}, B{sub 4}, and Al{sub 2}O{sub 3}) were exposed to x-rays from hohlraums in the Nova chamber. Ablated material was collected and measured on a receiving plate which was blocked form direct x-ray exposure. This article presents the results form these experiments and comparisons with predictions from numerical simulations The net condensation flux was calculated using the TSUNAMI code, which was modified to incorporate the feature of condensation boundaries.

Most radionuclide generation/depletion codes consider only neutron reactions and assume that charged particles, which may be generated in these reactions, deposit their energy locally without undergoing further nuclear interactions. Neglect of sequential charged-particle (x,n) reactions can lead to large underestimation in the inventories of radionuclides. PCROSS code was adopted for use with the ACAB activation code to enable calculation of the effects of (x,n) reactions upon radionuclide inventories and inventory-related indices. Activation calculations were made for Flibe (2LiF + BeF{sub 2}) coolant in the HYLIFE-II inertial fusion energy (IFE) power plant design. For pure Flibe coolant, it was found that (x,n) reactions dominate the residual contact dose rate at times of interest for maintenance and decommissioning. For impure Flibe, however, radionuclides produced directly in neutron reaction dominate the contact dose rate and (x,n) reactions do not make a significant contribution. Results demonstrate potential importance of (x,n) reactions and that the relative importance of (x,n) reactions varies strongly with the composition of the material considered. Future activation calculations should consider (x,n) reactions until a method for pre-determining their importance is established.

The National Ignition Facility Target Areas and Experimental Systems has reached mid-Title I design. Performance requirements for the Target Area are reviewed and design changes since the Conceptual Design Report are discussed. Development activities confirm a 5-m radius chamber and the viability of a boron carbide first wall. A scheme for cryogenic target integration with the NIF Target Area is presented.

Thermal analysis was performed for the proposed PUREX exhaust system after deactivation. The purpose of the analysis was to determine if condensation will occur in a sufficient quantity to plug or damage the filtration components. A heat transfer and fluid flow analysis was performed to evaluate the thermal characteristics of the underground duct system, the deep bed glass fiber (DBGF) filter No. 2, and the HEPA filters in the fourth filter building. The analysis is based on the extreme variations of air temperature, relative humidity, and dew point temperature using fifteen years of Hanford weather data as a basis. The results will be used to evaluate the need for electric heaters that are proposed for the PUREX canyon exhaust to prevent condensation.

Calculations of x-ray driven igniting implosions require several critical parameters which have been separately tested on Nova, viz., acceptable levels of SBS and SRS from plasmas equivalent to the plasmas in igniting hohlraums, quantitative understanding of radiation temperature in gas-filled hohlraums, demonstration of control of drive symmetry in gas-filled hohlraums, low levels of seeding of hydrodynamic instabilities from surfaces, especially cryogenic deuterium tritium ice, and quantitative understanding of the mix of cold fuel into a hot spot in high growth factor implosions. 14 refs.

High gain targets for inertial confinement fusion (ICF) contain a layer of deuterium-tritium (DT) ice which surrounds a volume of DT gas in thermal equilibrium with the solid. The roughness of the cryogenic fuel layer inside of ICF targets is one of the sources of imperfections which cause implosions to deviate from perfect one dimensional performance. Experiments at Lawrence Livermore National Laboratory have shown that applying a heat flux across the inner surface of a hydrogen layer such as that inside an ICF target reduces the intrinsic roughness of the surface. We have developed a technique to generate this heat flux by applying and electric field to the DT vapor in the center of these shells. This vapor has a small but significant conductivity due to ionization caused by beta decay of tritium in the vapor and the solid. We describe here experiments using a 1.15 GHz cavity to apply an electric field to frozen DT inside of a sapphire test cell. The cell and cavity geometry allows visual observation of the frozen layers.

We have developed a streaked imaging capability to make time-resolved measurements of the emission size for low density foam z-pinches. By lens coupling visible emission from the z-pinch target to an array of fiber optics we obtained the emission profile in the visible as a function of time with radial resolution of 300 {mu}m. To measure the emission at temperatures greater than {approx}40 eV the source was slit-imaged or pin-hole imaged onto an x-ray filtered scintillator. Non-uniformities in both visible and x-ray emission were observed. We describe the diagnostics, the image unfold process, and results from the instrument for both visible and x-ray measurements.

We have studied the effect of B and H on the charge density in Ni{sub 3}Al employing first-principles electronic structure calculations based on the FLMTO method. The changes in the electronic structure induced by B result from hybridization of d states of the nearest neighbor Ni atoms with adjacent B-{ital PP} states. Thus, boron prefers to occupy Ni-rich octahedral interstices [X(7)]. Boron greatly enhances the intraplanar metallic bonding between the Ni atoms, enhances the interplanar bonding between the NiAl layers in [001] direction, and reduces the bonding-charge directionality near the Ni(3) atoms. It is concluded that B acts to increase crystal cohesion. Hydrogen enhances the bonding-charge directionality near Ni(3) atoms and has virtually no interstitial charge enhancement, suggesting that H does not promote local cohesion. When both B and H are present, the dominant changes in the electronic structure induced by B and H seems to have little effect.