A program to identify and eliminate the causes of UV laser-induced damage and growth in fused silica and DKDP has developed methods to extend optics lifetimes for large-aperture, high-peak-power, UV lasers such as the National Ignition Facility (NIF). Issues included polish-related surface damage initiation and growth on fused silica and DKDP, bulk inclusions in fused silica, pinpoint bulk damage in DKDP, and UV-induced surface degradation in fused silica and DKDP in a vacuum. Approaches included an understanding of the mechanism of the damage, incremental improvements to existing fabrication technology, and feasibility studies of non-traditional fabrication technologies. Status and success of these various approaches are reviewed. Improvements were made in reducing surface damage initiation and eliminating growth for fused silica by improved polishing and post-processing steps, and improved analytical techniques are providing insights into mechanisms of DKDP damage. The NIF final optics hardware has been designed to enable easy retrieval, surface-damage mitigation, and recycling of optics.

We present a novel chirped pulse amplification method which combines optical parametric amplification and laser amplification. We have demonstrated this hybrid CPA concept with a combination of beta-barium borate and Ti:sapphire. High-efficiency, multi-terawatt compatible amplification is achieved without gain narrowing and without electro-optic modulators using a simple commercial pump laser.

A new process is being developed to extract starch from millfeed, the low-value byproduct of wheat flour milling, and convert it to glucose through enzymatic processing. The millfeed-derived glucose will then be converted to value-added products, such as polyol, through a catalytic process, or lactic acid, through a fermentation process. The starch (glucose) recovery process has been tested through the pilot scale. Catalytic and fermentation processes have been tested in the laboratory. The process developed for glucose recovery from wheat millfeed includes hot water extraction of starch and filtration of a fibrous animal feed coproduct, followed by enzymatic liquefaction and saccharification of the extracted starch, with filtration of a high-protein coproduct. The bench-scale tests showed that a glucose yield of approximately 30% on a dry millfeed basis could be achieved, which corresponds to the recovery of essentially all the glucose value in the millfeed. Glucose yields with the pilot-scale system were comparable, although filtration was more difficult.

We report here results from power balance measurements for ohmically-heated plasmas in the Sustained Spheromak Physics Experiment (SSPX). The plasma is formed inside a close-fitting tungsten-coated copper shell; wall conditioning by baking, glow discharge cleaning (GDC), Ti gettering, and helium shot conditioning produces clean plasmas (Z{sub eff} < 2.5) and reduces impurity radiation to a small fraction of the input energy, except when the molybdenum divertor plate has been overheated. We find that most of the input energy is lost by conduction to the walls (the divertor plate and the inner electrode in the coaxial source region). Recently, carborane was added during GDC to boronize the plasma-facing surfaces, but little benefit was obtained.

The passive corrosion rate of Alloy 22 is exceptionally low in a wide range of aqueous solutions, temperatures and electrochemical potentials, Alloy 22 contains approximately 22% chromium (Cr) by weight; thus, it forms a Cr-rich passive film in most environments. Very little is known about the composition, thickness and other properties of this passive film. The aim of this research was to determine the general characteristics of the oxide film that forms on Alloy 22, as a function of solution pH, temperature and applied electrochemical potential.

The National Ignition Facility will be the highest energy laser in the world when completed. Many small optics ({le} 14 inches in diameter) have stringent transport efficiency and some have very high laser fluence requirements. For optics to sustain high spectral efficiencies and survive high fluences for a 30-year operation, these optics have cleanliness requirements to assure optimal laser system performance. These optical components have insufficient surface areas to validate the particulate and organic contamination requirements by methods used for mechanical parts. Also, the common validation techniques require some sort of surface contact which is not compatible with handling of laser optics. This presentation describes alternate cleanliness validation methods developed for the NIF small optical components. An organic validation procedure was devised based on the spectral transmission sensitivity to contamination layers on coated and uncoated fused silica windows. Optics were scanned in the near infrared before and after an application of a specific amount of organic contamination onto the surface. Changes in transmission correlated to organic contamination levels and used to determine non-volatile organic contamination optics. A validation method for particulate contamination was demonstrated on a large window, showing that acceptable cleanliness levels could be achieved after a wet-wipe and …

A photon collider interaction region has the possibility of expanding the physics reach of a future TeV scale electron-positron collider. A survey of ongoing efforts to design the required lasers and optics to create a photon collider is presented in this paper.

We describe our recent progress in the area of solid-state heat-capacity-lasers (SSHCL). In particular, we examine the physics of heat-capacity operation of a solid state laser and give the present technology status of our 10 kW flashlamp-pumped laser The current status of work leading to a diode-pumped Nd:GGG HCL is also described.

With laser-driven tabletop x-ray lasers now operating in the efficient saturation regime, the source characteristics of high photon flux, high monochromaticity, picosecond pulse duration, and coherence are well-matched to many applications involving the probing of matter undergoing rapid changes. We give an overview of recent experiments at the Lawrence Livermore National Laboratory (LLNL) Compact Multipulse Terawatt (COMET) laser using the picosecond 14.7 nm x-ray laser as a compact, ultrafast probe for surface analysis and for interferometry of laser-produced plasmas. The plasma density measurements for known laser conditions allow us to reliably and precisely benchmark hydrodynamics codes. In the former case, the x-ray laser ejects photo-electrons, from the valence band or shallow core-levels of the material, and are measured in a time-of-flight analyzer. Therefore, the electronic structure can be studied directly to determine the physical properties of materials undergoing rapid phase changes.

We report new results using the LLNL COMET laser to evaluate the effectiveness of different target architectures to improve the output and characteristics of the transient x-ray laser scheme. Surprising observations were found when the laser line focus irradiating a single slab Cr or Fe target was divided into two or three distinct plasma column sections with millimeter scale gaps between each plasma. The Ne-like 3p {sup 1}S{sub 0} {yields} 3s {sup 1}P{sub 1} 28.5 nm and 25.5 nm x-ray laser lines, for Cr and Fe, respectively, were improved in beam divergence, by 2-3 times, and peak intensity, by up to one order of magnitude, when compared with a single plasma column of the same length or longer. This was contrary to expectations since these large-scale inhomogeneities introduced along the plasma, as well as attenuation from the cold plasma at the end of each section, would be detrimental to the x-ray propagation and amplification. Instead an injector-amplifier (IA) type process appears to be at work where the plasma gaps may be beneficially modifying the ray propagation and coupling through the high Ne-like ion gain regions. We present results showing the output of the amplifier stage with increasing length for the …

Size and composition are key factors in determining the impact aerosols have on global climate change and human health. The DELTA group at UC Davis has developed sampling techniques that allow continuous collection of aerosols separated into 8 different size fractions with 1-hour time resolution. Total aerosol mass determination: Scanning Transmission Ion Microscopy (STIM) with a 3 MeV proton beam can produce profiles of aerosol mass with an error limit of less than 10%. The aerosol collection strip is scanned with a proton beam of 50 micrometer spatial resolution while recording the proton mean energy loss as a function of position (Bench et al., 1992). A differential beta attenuation mass monitor (beta-gauge) is also used for mass determination. The beta-gauge consists of a 63Ni source and a surface barrier detector. This technique allows quantitative mass measurement by recording attenuation of beta particles through the sample and substrate (Chueinta and Hopke, 2001). Mineral mass and elemental composition: Synchrotron X-ray Fluorescence (s-XRF) is performed at the Advanced Light Source (ALS) at LBNL. The s-XRF technique is quantitative for elements Na through U. The ALS synchrotron provides an extraordinarily intense white beam of X-rays (4-20 KeV) that are 100% polarized. These properties provide …

This paper describes the design of the downstream beam transport line for the second axis of the Dual Axis Radiographic Hydrodynamic Test (DARHT-II) Facility. The DARHT-II project is a collaboration between LANL, LBNL and LLNL. DARHT II is a 18.4-MeV, 2000-Amperes, 2-{micro}sec linear induction accelerator designed to generate short bursts of x-rays for the purpose of radiographing dense objects. The downstream beam transport line is approximately 22-meter long region extending from the end of the accelerator to the bremsstrahlung target. The principal element of the beam transport section is the fast deflector, or kicker system, used to generate four micropulses from the primary accelerator beam. Within this proposed transport line there are also several conventional solenoid, quadrupole and dipole magnets which transport and focus the beam to the target and to the beam dumps.

Theoretical studies aimed at predicting and diagnosing field-line quality in a spheromak are described. These include nonlinear 3-D MHD simulations, stability studies, analyses of confinement in spheromaks dominated by either open (stochastic) field lines or approximate flux surfaces, and a theory of fast electrons as a probe of field-line length.

We analyze the structure of supersymmetric Godel-like cosmological solutions of string theory. Just as the original four-dimensional Godel universe, these solutions represent rotating, topologically trivial cosmologies with a homogeneous metric and closed timelike curves. First we focus on"phenomenological" aspects of holography, and identify the preferred holographic screens associated with inertial comoving observers in Godel universes. We find that holography can serve as a chronology protection agency: The closed timelike curves are either hidden behind the holographic screen, or broken by it into causal pieces. In fact, holography in Godel universes has many features in common with de Sitter space, suggesting that Godel universes could represent a supersymmetric laboratory for addressing the conceptual puzzles of de Sitter holography. Then we initiate the investigation of"microscopic" aspects of holography of Godel universes in string theory. We show that Godel universes are T-dual to pp-waves, and use this fact to generate new Godel-like solutions of string and M-theory by T-dualizing known supersymmetric pp-wave solutions.

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Cross sections for photoionization of doubly-chargedscandium ions has been measured using a merged-beams technique. Resultsare compared with the time-reversed process ofphotorecombination.

An application of alkyne metathesis to 1,2-di(prop-1-ynyl)arenes, producing dehydrobenzannulenes, is described. An efficient method for selective Sonogashira couplings of bromoiodoarenes under conditions of microwave irradiation is also reported.

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This paper reports on a combined experimental and modeling investigation of NOx formation in nitrogen-diluted laminar methane diffusion flames seeded with ammonia. The methane-ammonia mixture is a surrogate for biomass fuels which contain significant fuel-bound nitrogen. The experiments use flue-gas sampling to measure the concentration of stable species in the exhaust gas, including NO, O2, CO, and CO2. The computations evolve a two-dimensional low Mach number model using a solution-adaptive projection algorithm to capture fine-scale features of the flame. The model includes detailed thermodynamics and chemical kinetics, differential diffusion, buoyancy, and radiative losses. The model shows good agreement with the measurements over the full range of experimental NH3 seeding amounts. As more NH3 is added, a greater percentage is converted to N2 rather than to NO. The simulation results are further analyzed to trace the changes in NO formation mechanisms with increasing amounts of ammonia in the fuel.

Tungstophosphoric Acid (HPW) has been investigated using different spectroscopic and chemical techniques. Bulk sensitive techniques such as x-ray diffract ion (XRD) and infrared (IR) spectroscopy indicate that the acid is stable at temperatures as high as 300 degrees C or higher. However, our work suggests that HPW starts loosing stability at temperature as low as 200 degrees C. For instance, P 2p peak was not detected in the XPS spectrum of HPW preheated at 100 degrees C, but was clearly observed after preheating the acid at 200 degrees C and 400 degrees C. This suggests the destruction of the molecules of the surface leading to the enrichment of surface with phosphorus. These results may explain why HPW deactivates very fast, e.g., 8 min at 200 degrees C, in hexane cracking experiments. This could limit the use of HPW in surface reactions that even require moderate temperatures. Detailed infrared spectroscopic investigation of the HPW as a function of temperature showed a gradual in crease in absorbance of the W-O-W corner shared vibration relative to the absorbance of the other bands. This indicates that the symmetry, and hence the stability, of the molecule was decreased upon heating.

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The KTeV physics program encompasses many goals including a precision measurement of the direct CP violation parameter Re({epsilon}{prime}/{epsilon}) in K{sub S,L} {yields} {pi}{pi} decays, and studies of rare neutral kaon decays. The KTeV detector collected data during the Fermilab fixed-target runs of 1996-97 and 1999. This article focuses on the precision measurement of the direct CP violation parameter Re({epsilon}{prime}/{epsilon}) using the 1996-97 data set. In addition, measurements of the neutral kaon parameters {tau}{sub s}, {Delta}m, {phi}{sub {+-}}, {Delta}{phi} from that data set and a new measurement of the branching fraction of K{sub L} {yields} e{sup +}e{sup -} {mu}{sup +}{mu}{sup -} from the 1997 and 1999 data also are presented.

Eddy current (EC) estimate of flaw size obtained from inservice inspection is often the primary means of assessing the structural integrity of steam generator tubes. Reliable prediction of failure pressure and leak rate in tubes with complex cracking requires more detailed information about the geometry and extent of degradation than is generally available from conventional bobbin coil examinations. High-resolution inspections with EC rotating probes are thus carried out on selected regions of tubing to provide the more extensive nondestructive evaluation (NDE) information that is needed to better assess flaw size and distribution. Interpretation of signals from complex cracking that are often distorted by coherent and incoherent noise can be a challenging NDE task. Studies at Argonne National Laboratory have demonstrated that computer-aided data analysis can be used for more accurate and efficient processing of the large amounts of data collected by such probes. The basic structure of a rule-based multiparameter data analysis algorithm is described in this paper. Multiple-frequency inspection data from a standard rotating pancake coil were used for the analyses. The codes were implemented as MATLAB scripts and provide, as the final outcome, profiles of flaw depth in a section of tube. Graphical user interface tools were devised …

We describe some algorithms and tools that have been developed to generate composite overlapping grids on geometries that have been defined with computer aided design (CAD) programs. This process consists of five main steps. Starting from a description of the surfaces defining the computational domain we (1) correct errors in the CAD representation, (2) determine topology of the patched-surface, (3) build a global triangulation of the surface, (4) construct structured surface and volume grids using hyperbolic grid generation, and (5) generate the overlapping grid by determining the holes and the interpolation points. The overlapping grid generator which is used for the final step also supports the rapid generation of grids for block-structured adaptive mesh refinement and for moving grids. These algorithms have been implemented as part of the Overture object-oriented framework.