Compact and stable multibeam fiber injector

A compact and stable 20-beam injector was built for launching laser light into fibers for Fabry Perot velocity measurements of shock-driven surfaces. The fiber injector uses commercial mounts on mini-rails. Dielectric-coated beamsplitters provide accurate amplitude division. Minimal adjustments for stable operation are permitted by the use of a real-time video-viewer. The video system includes a non-linear camera for CW alignment and a linearized camera with a frame grabber for pulsed measurement and analysis. All 20-injection points are displayed on a single monitor. Optical requirements are given for image relay and magnification. Stimulated Brillouin scattering limitations on high-power are quantified

High gain x-ray lasers pumped by transient collisional excitation

We present recent results of x-ray laser amplification of spontaneous emission in Ne-like and Ni-like transient collisional excitation schemes. The plasma formation, ionization and collisional excitation can be optimized using two laser pulses of 1 ns and 1 ps duration at table-top energies of 5 J in each beam. High gain of 35 cm{sup -1} has been measured on the 147 {Angstrom} 4d{r_arrow}4p J=0{r_arrow}1 transition of Ni-like Pd and is a direct consequence of the nonstationary population inversion produced by the high intensity picosecond pulse. We report the dependence of the x-ray laser line intensity on the laser plasma conditions and compare the experimental measurements with hydrodynamic and atomic kinetics simulations for Ne-like and Ni-like lasing

New methods in WARP, a particle-in-cell code for space-charge dominated beams

The current U.S. approach for a driver for inertial confinement fusion power production is a heavy-ion induction accelerator; high-current beams of heavy ions are focused onto the fusion target. The space-charge of the high-current beams affects the behavior more strongly than does the temperature (the beams are described as being ``space-charge dominated``) and the beams behave like non-neutral plasmas. The particle simulation code WARP has been developed and used to study the transport and acceleration of space-charge dominated ion beams in a wide range of applications, from basic beam physics studies, to ongoing experiments, to fusion driver concepts. WARP combines aspects of a particle simulation code and an accelerator code; it uses multi-dimensional, electrostatic particle-in-cell (PIC) techniques and has a rich mechanism for specifying the lattice of externally applied fields. There are both two- and three-dimensional versions, the former including axisymmetric (r-z) and transverse slice (x-y) models. WARP includes a number of novel techniques and capabilities that both enhance its performance and make it applicable to a wide range of problems. Some of these have been described elsewhere. Several recent developments will be discussed in this paper. A transverse slice model has been implemented with the novel capability of including bends, allowing more rapid simulation while retaining essential physics. An interface using Python as the interpreter layer instead of Basis has been developed. A parallel version of WARP has been developed using Python

Reuse of waste cutting sand at Lawrence Livermore National Laboratory

Lawrence Livermore National Laboratory (LLNL) examined the waste stream from a water jet cutting operation, to evaluate the possible reuse of waste garnet sand. The sand is a cutting agent used to shape a variety of materials, including metals. Nearly 70,000 pounds of waste sand is generated annually by the cutting operation. The Environmental Protection Department evaluated two potential reuses for the spent garnet sand: backfill in utility trenches; and as a concrete constituent. In both applications, garnet waste would replace the sand formerly purchases by LLNL for these purposes. Findings supported the reuse of waste garnet sand in concrete, but disqualified its proposed application as trench backfill. Waste sand stabilized in ac concrete matrix appeared to present no metals-leaching hazard; however, unconsolidated sand in trenches could potentially leach metals in concentrations high enough to threaten ground water quality. A technical report submitted to the San Francisco Bay Regional Water Quality Control Board was reviewed and accepted by that body. Reuse of waste garnet cutting sand as a constituent in concrete poured to form walkways and patios at LLNL was approved

BBN technical memorandum W1310 hydroacoustic network capability studies

This report summarizes work performed under contract to Lawrence Livermore National Laboratory during the period 1 August to 30 November 1997. Four separate tasks were undertaken during this period which investigated various aspects of hydroacoustic network performance using the Hydroacoustic Coverage Assessment Model (HydroCAM). The purpose of this report is to document each of these tasks

Landmine policy in the near-term: a framework for technology analysis and action

Any effective solution to the problem of leftover landmines and other post-conflict unexploded ordnance (UXO) must take into account the real capabilities of demining technologies and the availability of sufficient resources to carry out demining operations. Economic and operational factors must be included in analyses of humanitarian demining. These factors will provide a framework for using currently available resources and technologies to complete this task in a time frame that is both practical and useful. Since it is likely that reliable advanced technologies for demining are still several years away, this construct applies to the intervening period. It may also provide a framework for utilizing advanced technologies as they become available. This study is an economic system model for demining operations carried out by the developed nations that clarifies the role and impact of technology on the economic performance and viability of these operations. It also provides a quantitative guide to assess the performance penalties arising from gaps in current technology, as well as the potential advantages and desirable features of new technologies that will significantly affect the international community`s ability to address this problem. Implications for current and near-term landmine and landmine technology policies are drawn

Review of existing reactive transport software

Simulations of thermal and hydrological evolution following the potential emplacement of a subterranean nuclear waste repository at Yucca Mountain, NV provide data that suggest the inevitability of dependent, simultaneous chemical evolution in this system. These chemical changes will modify significantly both the magnitude and structure of local porosity and permeability; hence, they will have a dynamic feedback effect on the evolving thermal and hydrological regime. Yet, despite this intimate interdependence of transport and chemical processes, a rigorous quantitative analysis of the post- emplacement environment that incorporates this critical feedback mechanism has not been completed to date. As an initial step in this direction, the present document outlines the fundamental chemical and transport processes that must be accounted for in such an analysis, and reviews the inventory of existing software that encodes these processed in explicitly coupled form. A companion report describes the prioritization of specific capabilities that are needed for modeling post-emplacement reactive transport at Yucca Mountain

Large aperture Fresnel telescopes/011

At Livermore we`ve spent the last two years examining an alternative approach towards very large aperture (VLA) telescopes, one based upon transmissive Fresnel lenses rather than on mirrors. Fresnel lenses are attractive for VLA telescopes because they are launchable (lightweight, packagable, and deployable) and because they virtually eliminate the traditional, very tight, surface shape requirements faced by reflecting telescopes. Their (potentially severe) optical drawback, a very narrow spectral bandwidth, can be eliminated by use of a second (much smaller) chromatically-correcting Fresnel element. This enables Fresnel VLA telescopes to provide either single band ({Delta}{lambda}/{lambda} {approximately} 0.1), multiple band, or continuous spectral coverage. Building and fielding such large Fresnel lenses will present a significant challenge, but one which appears, with effort, to be solvable

Frozen plasma within the flow from a metal plate hit by an electron beam pulse

When a pulsed electron beam hits a metal plate with sufficient energy a volume of the metal becomes hot fluid that subsequently sprays out of the plate. A portion of this flow is ionized. This report describes a fluid that expands so rapidly into a vacuum that the ionized portion of the flow departs from local thermodynamic equilibrium. This cold supersonic exhaust will have a much higher degree of ionization, and of higher electron temperature, than would be expected from a gas in thermodynamic equilibrium at the local temperature of the neutral flow. This report presents a continuation of the work described in reference (1). My aim is to develop as simple a model as will reasonably predict the speed and density of neutral flow, and the temperature and density of plasma. I use simplifying assumptions and mathematical approximations to develop convenient formulas, and I test them by comparing specific examples to experimental data and computations by DeVolder and other Los Alamos scientists (2). The phenomenon of sudden expansion of a gas cloud into vacuum is described in several sections of the two-volume work by ZelUdovich and Raizer (3). The criterion I use for estimating the point in the flow where plasma ceases to be in equilibrium is in principle that proposed by Bray (4), (5), and discussed extensively by Vincenti and Kruger (6). The immediate concern motivating this work is how to design a metal target that accurately converts an electron beam pulse train into a radiation pulse train for use in the high-speed radiography of implosion hydrodynamics experiments. In the radiography application, either the electron beam must be swept magnetically along the metal target more quickly than the spread of the debris plume, or the metal plate must move laterally past a fixed point of impact, carrying its plume with it. What is this speed, and how dense is this splash flow? Aside from its technological application, this problem has an intrinsic interest because it includes such a wide range of physical phenomena, and because it is an analog in miniature of supernova explosions. A small hot source created quickly propels an expanding flow into a vacuum, and this flow contains a remnant plasma that preserves information about the earliest moments of the flow. The plan of this report is as follows. The section ``Heat source and neutral flow`` reviews the physics of an electron beam pulse that generates enthalpy, which in turn propels a flow of neutral target material. The section ``Thermal plasma`` shows the Saha equation used to estimate the initial degree of ionization in the fluid and the collisional ionization rate coefficient used. The section ``Frozen flow`` describes the criterion that indicates when plasma has ceased to be in thermodynamic equilibrium with the neutral flow. The section ``An Example`` shows a specific case that was originally measured and calculated at Los Alamos, and described in reference (2)

New concept of small power reactor without on-site refueling for non-proliferation

Energy demand in developing countries is increasing to support growing populations and economies. This demand is expected to continue growing at a rapid pace well into the next century. Because current power sources, including fossil, renewable, and nuclear, cannot meet energy demands, many developing countries are interested in building a new generation of small reactor systems to help meet their needs. The U.S. recognizes the need for energy in the developing countries. In its 1998 Comprehensive Energy Strategy, the Department of Energy calls for research into low-cost, proliferation- resistant, nuclear reactor technologies to ensure that this demand can be met in a manner consistent with U.S. non-proliferation goals and policies. This research has two primary thrusts: first, the development of a small proliferation-resistant nuclear system (i.e., a technology focus); second, the continuation of open communication with the international community through early engagement and cooperation on small reactor development. A system that meets developing country requirements must: (1) achieve reliably safe operation with a minimum of maintenance and supporting infrastructure; (2) offer economic competitiveness with alternative energy sources available to the candidate sites; and (3) demonstrate significant improvements in proliferation resistance relative to existing reactor systems. These challenges are the most significant driving forces behind the LLNL proposed program for development of a new, small nuclear reactor system. This report describes a technical approach for developing small nuclear power systems for use in developing countries. The approach being proposed will establish a preliminary set of requirements that, if met, will cause new innovative approaches to system design to be used. The proposed approach will borrow from experience gained over the past forty years with four types of nuclear reactor technologies (LWR, LMR, HTGR, and MSR) to develop four or more pre-conceptual designs. The pre-conceptual designs will be used to confirm the adequacy of the requirements through iteration and trade studies. A down selection to a preferred and backup concept would be made following a 12-18 month design effort. The selected designs, system design specifications, and the necessary R&D programs would be developed in greater detail over the next three and one-half years. A reactor in the 50 to 150 MWe class, nominally 100 MWe, shows the best potential for meeting these challenges. The system will have unique characteristics to achieve proliferation resistance, and will maximize the reliance on passive safety features to reduce the risk of serious accidents and their consequences, simplify operations and maintenance, and reduce the need for the developing country to establish a sophisticated and expensive nuclear infrastructure. In particular, to eliminate all on- site refueling, the reactor will be equipped with a long-life core that will be returned to the supplier when spent. This process will be managed under international control to further both overall non- proliferation objectives and to reduce the infrastructure burden on the developing country. It will also reduce the anticipated burden and expense to the International Atomic Energy Agency for assuring security associated with expanded international use of nuclear energy. An integral part of the program will be the development of new approaches for implementing international safeguards applicable to the entire fuel cycle including recycling and waste disposal. The report discusses the preliminary requirements and the rationale for selecting them. It then discusses the four nuclear system technologies and how they might proceed to meet the requirements. Brief discussions are provided on the approaches to stimulating the appropriate international and industrial participation necessary to finance development of a design with improved proliferation resistance that is useful to the developing countries