The National Ignition Facility: Status and Plans for Laser Fusion and High-Energy-Density Experimental Studies (open access)

The National Ignition Facility: Status and Plans for Laser Fusion and High-Energy-Density Experimental Studies

The National Ignition Facility (NIF), currently under construction at the University of California's Lawrence Livermore National Laboratory is a $2.25B stadium-sized facility containing a 192-beam, 1.8-Megajoule, 500-Terawatt, 351-nm laser system. NIF is being built by the National Nuclear Security Agency and when completed will be the world's largest laser system, providing a national center to study inertial confinement fusion and the physics of extreme energy densities and pressures. In NIF up to 192 energetic laser beams will compress small fusion targets to conditions where they will ignite and burn, liberating more energy than is required to initiate the fusion reactions. NIF experiments will allow the study of physical processes at temperatures approaching 100 million K and 100 billion times atmospheric pressure. These conditions exist naturally only in the interior of stars and in nuclear weapons explosions. In the course of designing the world's most energetic laser system, a number of significant technology breakthroughs have been achieved. Research is also underway to develop a shorter pulse capability on NIF for high power applications. We discuss here the technology challenges and solutions that have made NIF possible along with enhancements to NIF's design that could lead to exawatt power levels.
Date: January 11, 2002
Creator: Moses, E I
Object Type: Article
System: The UNT Digital Library
Hierarchical Volume Representation with 3{radical}2 Subdivision and Trivariate B-Spline Wavelets (open access)

Hierarchical Volume Representation with 3{radical}2 Subdivision and Trivariate B-Spline Wavelets

Multiresolution methods provide a means for representing data at multiple levels of detail. They are typically based on a hierarchical data organization scheme and update rules needed for data value computation. We use a data organization that is based on what we call n{radical}2 subdivision. The main advantage of subdivision, compared to quadtree (n = 2) or octree (n = 3) organizations, is that the number of vertices is only doubled in each subdivision step instead of multiplied by a factor of four or eight, respectively. To update data values we use n-variate B-spline wavelets, which yields better approximations for each level of detail. We develop a lifting scheme for n = 2 and n = 3 based on the n{radical}2-subdivision scheme. We obtain narrow masks that could also provide a basis for view-dependent visualization and adaptive refinement.
Date: January 11, 2002
Creator: Linsen, L; Gray, JT; Pascucci, V; Duchaineau, M & Hamann, B
Object Type: Article
System: The UNT Digital Library
Kinetics of Solid Phase Reactions at High Pressure and Temperature (open access)

Kinetics of Solid Phase Reactions at High Pressure and Temperature

We report on the subject of temperature and/or pressure induced solid-solid phase transitions of energetic molecular crystals. Over the last three years we have applied experimental techniques that when used simultaneously provide insight into some of the complexities that govern reaction rate processes. After more than 55 years of study a global kinetics model describing the P-T phase space transition kinetics of such materials as HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) is not only missing, but from a formal perspective is perhaps as many years away from completion. The essence of this report describes what material parameters affect first-order reaction rates of the CHNO moiety of molecular crystals and introduces the application of new experimental tools thus permitting quantifiable studies of important rate limiting mechanisms.
Date: February 11, 2002
Creator: Zaug, J M; Farber, D L; Saw, C K & Weeks, B L
Object Type: Report
System: The UNT Digital Library
Hydrogen Peroxide Gas Generator Cycle with a Reciprocating Pump (open access)

Hydrogen Peroxide Gas Generator Cycle with a Reciprocating Pump

A four-chamber piston pump is powered by decomposed 85% hydrogen peroxide. The performance envelope of the evolving 400 gram pump has been expanded to 172 cc/s water flow at discharge pressures near 5 MPa. A gas generator cycle system using the pump has been tested under similar conditions of pressure and flow. The powerhead gas is derived from a small fraction of the pumped hydrogen peroxide, and the system starts from tank pressures as low as 0.2 MPa. The effects of steam condensation on performance have been evaluated.
Date: June 11, 2002
Creator: Whitehead, J C
Object Type: Article
System: The UNT Digital Library
Pressure Measurements in a PBX 9501 Gauged Acceptor When Impacted by a Steel Plate that is Accelerated by a Thermally Cooked Off PBX 9501 Charge (open access)

Pressure Measurements in a PBX 9501 Gauged Acceptor When Impacted by a Steel Plate that is Accelerated by a Thermally Cooked Off PBX 9501 Charge

Measuring the violence of a thermal explosion of a cased explosive is important for evaluating safety issues of explosive devices in fires. A sympathetic initiation scenario was studied here where a 9.0 cm diameter by 2.5 cm thick disc of PBX 9501 donor charge encased in a 304 stainless steel assembly was heated on top and bottom flat surfaces until it thermally exploded. The initial heating rate at the metal/explosive interface was 5 C per minute until it reaches 170 C; then this temperature is held for 35 minutes to allow temperature equilibration to within a few degrees throughout the explosive. The heating resumed at a rate of 1 C per minute until the PBX 9501 donor thermally exploded. A PBX 9501 acceptor charge with carbon resistor and manganin foil pressure gauges inserted at various depths was placed at a 10 cm standoff distance from the donor charge's top steel cover plate. Piezoelectric arrival time pins were placed in front of the acceptor surface to measure the velocity and shape of the impacting plate. The stainless steel cover plate of the donor charge had a nominal velocity of 0.55 {+-} 0.04 mm/{micro}s upon impact and was non-symmetrically warped. The impact …
Date: March 11, 2002
Creator: Forbes, J W; Garcia, F; Urtiew, P A; Vandersall, K S; Greenwood, D W & Tarver, C M
Object Type: Article
System: The UNT Digital Library
Effects of Introduced Materials in the Drift Scale Test (open access)

Effects of Introduced Materials in the Drift Scale Test

Water samples previously acquired from superheated (>140 C) zones within hydrological test boreholes of the Drift Scale Test (DST) show relatively high fluoride concentrations (5-66 ppm) and low pH (3.1-3.5) values. In these high temperature regions of the rock, water is present superheated vapor only--liquid water for sampling purposes is obtained during the sampling process by cooling. Based on data collected to date, it is evident that the source of the fluoride and low pH is from introduced man-made materials (Teflon{trademark} and/or Viton{trademark} fluoroelastomer) used in the test. The test materials may contribute fluoride either by degassing hydrogen fluoride (HF) directly to produce trace concentrations of HF gas ({approx}0.1 ppm) in the high temperature steam, or by leaching fluoride in the sampling tubes after condensation of the superheated steam. HF gas is known to be released from Viton{trademark} at high temperatures (Dupont Dow Elastomers L.L.C., Elkton, MD, personal communication) and the sample water compositions indicate near stoichiometric balance of hydrogen ion and fluoride ion, indicating dissolution of HF gas into the aqueous phase. These conclusions are based on a series of water samples collected to determine if the source of the fluoride is from the degradation of materials originally installed …
Date: January 11, 2002
Creator: DeLoach, L & Jones, RL
Object Type: Report
System: The UNT Digital Library
Review of Excess Weapons Plutonium Disposition LLNL Contract Work in Russia-(English) (open access)

Review of Excess Weapons Plutonium Disposition LLNL Contract Work in Russia-(English)

This third meeting of the recently completed and ongoing Russian plutonium immobilization contract work was held at the State Education Center (SEC) in St. Petersburg on January 14-18, 2002. The meeting agenda is reprinted here as Appendix A and the attendance list as Appendix B. The meeting had 58 Russian participants from 21 Russian organizations, including the industrial sites (Mayak, Krasonayarsk-26, Tomsk), scientific institutes (VNIINM, KRI, VNIPIPT, RIAR), design organizations (VNIPIET and GSPI), universities (Nyzhny Novgorod, Urals Technical), Russian Academy of Sciences (Institute of Physical Chemistry or IPhCh, Institute of Ore-Deposit Geology, Petrography, Mineralogy, and Geochemistry or IGEM), Radon-Moscow, S&TC Podol'osk, Kharkov-Ukraine, GAN-SEC-NRS and SNIIChM, the RF Ministry of Atomic Energy (Minatom) and Gosatomnadzor (GAN). This volume, published by LLNL, documents this third annual meeting. Forty-nine technical papers were presented by the Russian participants, and nearly all of these have been collected in this Proceedings. The two objectives for the meeting were to: (1) Bring together the Russian organizations, experts, and managers performing this contract work into one place for four days to review and discuss their work amongst each other. (2) Publish a meeting summary and proceedings of all the excellent Russian plutonium immobilization and other plutonium disposition contract …
Date: July 11, 2002
Creator: Jardine, L & Borisov, G B
Object Type: Report
System: The UNT Digital Library
Deflagration Behavior of PBXN-109 and Composition B at High Pressures and Temperatures (open access)

Deflagration Behavior of PBXN-109 and Composition B at High Pressures and Temperatures

We report deflagration rate measurements on PBXN-109 (RDWAVHTPB) and Composition B (RXDTTNThrvax) at pressures from 1,500-100,000 psi (10-700 MPa). This was done with the LLNL High Pressure Strand Burner, in which embedded wires are used to record the time-of-arrival of the burn front in the cylindrical sample as a function of pressure. The propellant samples are 6.4 mm in diameter and 6.4 mm long, with burn wires inserted between samples. Burning on the cylindrical surface is inhibited with an epoxy or polyurethane layer. With this direct measurement we do not have to account for product gas equation of state or heat losses in the system, and the burn wires allow detection of irregular burning. We report deflagration results for PBXN-109 as received, and also after it has been damaged by heating. The burn behavior of pristine PBXN-109 is very regular, and exhibits a reduction in pressure exponent from 1.32 to 0.85 at pressures above 20,000 psi (135 MPa). When PBXN-109 is thermally damaged by heating to 170-180 C, the deflagration rate is increased by more than a factor of 10. This appears to be a physical effect, as the faster burning may be explained by an increase in surface area. …
Date: March 11, 2002
Creator: Maienschein, J L & Wardell, J F
Object Type: Article
System: The UNT Digital Library
Progressive Precision Surface Design (open access)

Progressive Precision Surface Design

We introduce a novel wavelet decomposition algorithm that makes a number of powerful new surface design operations practical. Wavelets, and hierarchical representations generally, have held promise to facilitate a variety of design tasks in a unified way by approximating results very precisely, thus avoiding a proliferation of undergirding mathematical representations. However, traditional wavelet decomposition is defined from fine to coarse resolution, thus limiting its efficiency for highly precise surface manipulation when attempting to create new non-local editing methods. Our key contribution is the progressive wavelet decomposition algorithm, a general-purpose coarse-to-fine method for hierarchical fitting, based in this paper on an underlying multiresolution representation called dyadic splines. The algorithm requests input via a generic interval query mechanism, allowing a wide variety of non-local operations to be quickly implemented. The algorithm performs work proportionate to the tiny compressed output size, rather than to some arbitrarily high resolution that would otherwise be required, thus increasing performance by several orders of magnitude. We describe several design operations that are made tractable because of the progressive decomposition. Free-form pasting is a generalization of the traditional control-mesh edit, but for which the shape of the change is completely general and where the shape can be placed …
Date: January 11, 2002
Creator: Duchaineau, M & Joy, KJ
Object Type: Article
System: The UNT Digital Library
NEUTRINOS, PAST AND PRESENT. (open access)

NEUTRINOS, PAST AND PRESENT.

None
Date: October 11, 2002
Creator: GOLDHABER,M.
Object Type: Article
System: The UNT Digital Library
Route to High Temperatures by Current Amplification in the Sustained Spheromak Physics Experiment (SSPX) (open access)

Route to High Temperatures by Current Amplification in the Sustained Spheromak Physics Experiment (SSPX)

For the spheromak to be attractive as a reactor concept it would be necessary to sustain the configuration with a low recycling power, reflected in the current amplification factor: A{sub 1} = I{sub tor}/I{sub gun}, where I{sub tor} is the toroidal current and I{sub gun} is the gun current. It is understood that A{sub 1} needs to be around 60 for a reactor [1], although the highest obtained so far in the spheromak has been {approx}3 [2]. The spheromak is a simply connected toroidal confinement device related to the reversed field pinch in that the q-profile falls at the edge and the first wall is conducting, although the central solenoid is absent. In the spheromak, the paradigm for field generation (and hence current amplification) is the injection of helicity, K = {integral}A.BdV = 2{Phi}{Psi} where {phi} and {Psi} are linked fluxes. Helicity is additive in the process of electrostatic injection by a coaxial gun [3]: K = 2V{sub gun{Psi}gun}, where V{sub gun} is the voltage applied between two coaxial electrodes (giving the rate of toroidal flux injection) and {Psi}{sub gun} is the poloidal vacuum flux connecting them. SSPX [4] is a 1m wide coaxial-gun-driven spheromak with W-coated copper electrodes (FIGURE …
Date: June 11, 2002
Creator: Woodruff, S.; Holbomb, C. T.; Stallard, B. W.; Hill, D. N.; Hooper, E. B.; McLean, H. S. et al.
Object Type: Article
System: The UNT Digital Library
Hydroacoustic Evaluation of Fish-Passage Efficiency at Bonneville Dam in 2001 (open access)

Hydroacoustic Evaluation of Fish-Passage Efficiency at Bonneville Dam in 2001

The Portland District of the U.S. Army Corps of Engineers requested that scientists with the Pacific Northwest National Laboratory (PNNL) and the U.S. Army Engineer Research and Development Center (ERDC) conduct the hydroacoustic fish-passage studies described in this report. The ERDC also contracted with MEVATEC Corporation and Dyntel to provide staff ranging from scientists to technicians for the study. This study supports the Portland-District goal of maximizing fish passage efficiency (FPE) and obtaining 95% survival for juvenile salmon passing the Bonneville Project. This report presents results of two hydroacoustic studies of juvenile salmonids. One was a Project-wide study of fish-passage efficiency, and the other was more narrowly focused upon the approach, vertical distribution, and fish-guidance efficiency (FGE) of fish at Unit 15, where the Portland District extensively modified the gatewell and vertical barrier screen to improve gatewell flow and FGE. The goal of the larger of the two studies was to provide project-wide estimates of FPE, spill efficiency, and spill effectiveness for run-of-river fish passing the Bonneville Project during the 2001 out-migration. This type of study also provides estimates of the horizontal, vertical, and diel distributions of fish passage and FGE by turbine unit. These data will provide a baseline …
Date: October 11, 2002
Creator: Ploskey, Gene R.; Schilt, Carl R.; Hanks, Michael E.; Johnson, Peter N.; Kim, Jina; Skalski, John R. et al.
Object Type: Report
System: The UNT Digital Library
Kull ALE: II. Grid Motion on Unstructured Arbitrary Polyhedral Meshes (open access)

Kull ALE: II. Grid Motion on Unstructured Arbitrary Polyhedral Meshes

Several classes of mesh motion algorithms are presented for the remap phase of unstructured mesh ALE codes. The methods range from local shape optimization procedures to more complex variational minimization methods applied to arbitrary unstructured polyhedral meshes necessary for the Kull code.
Date: February 11, 2002
Creator: Anninos, P
Object Type: Report
System: The UNT Digital Library
Solution Based Deposition of Polyimide Ablators for NIF Capsules (open access)

Solution Based Deposition of Polyimide Ablators for NIF Capsules

Between June 1997 and March 2002 Luxel Corporation was contracted to explore the possibility of preparing NIF scale capsules with polyimide ablators using solution-based techniques. This work offered a potential alternative to a vapor deposition approach talking place at LLNL. The motivation for pursuing the solution-based approach was primarily two-fold. First, it was expected that much higher strength capsules (relative to vapor deposition) could be prepared since the solution precursors were known to produce high strength films. Second, in applying the ablator as a fluid it was expected that surface tension effects would lead to very smooth surfaces. These potential advantages were offset by expected difficulties, primary among them that the capsules would need to be levitated in some fashion (for example acoustically) during coating and processing, and that application of the coating uniformly to thicknesses of 150 pm on levitated capsules would be difficult. Because of the expected problems with the coupling of levitation and coating, most of the initial effort was to develop coating and processing techniques on stalk-mounted capsules. The program had some success. Using atomizer spray techniques in which application of {approx}5 {micro}m fluid coatings were alternated with heating to remove solvent resulted in up to …
Date: July 11, 2002
Creator: Cook, R
Object Type: Report
System: The UNT Digital Library
Absorption Spectra of Broadened Sodium Resonance Lines in Presence of Rare Gases (open access)

Absorption Spectra of Broadened Sodium Resonance Lines in Presence of Rare Gases

The pressure broadening of alkali-metal lines is a fundamental problem with numerous applications. For example, the sodium resonance lines broadened by xenon are important in the production of broad spectra emitted in the HPS (High-Pressure Sodium) lamp and they potentially can be used for gas condition diagnostics. Broadened absorption lines of alkali-metal atoms are prominent in the optical spectra of brown dwarfs and understanding the broadening mechanism will help elucidate the chemical composition and atmospheric properties of those stars. The far-line wing spectra of sodium resonance lines broadened by rare gases are found to exhibit molecular characteristics such as satellites and hence the total absorption coefficients for vapors of Na atoms and perturbing rare gas atoms can be modeled as Na-RG (rare gas) molecular absorption spectra. In this work, using carefully chosen interatomic potentials for Na-RG molecules we carry out quantum-mechanical calculations for reduced absorption coefficients for vapors composed of Na-He, Na-Ar, and Na-Xe. Calculated spectra are compared to available experimental results and the agreement is good in the measured satellite positions and shapes.
Date: September 11, 2002
Creator: Chung, H-K; Shurgalin, M & Babb, J F
Object Type: Article
System: The UNT Digital Library
Detection of Materials of Interest to Non-Proliferation: A Novel Approach (open access)

Detection of Materials of Interest to Non-Proliferation: A Novel Approach

We propose the development of a novel detector that can locate and identify materials of interest to Nuclear Arms Non Proliferation. The device will combine nuclear acoustic resonance (NAR) with superconducting quantum interference device (SQUID) widely used in nuclear magnetic resonance (NMR), geophysics, nondestructive evaluations, and biomagnetism, to name only few. NAR works like NMR. Thus resonant absorption (of applied ultrasonic energy) by a nuclear spin system occurs when the ultrasonic frequency is equal to the appropriate frequency separations between the magnetic nuclear energy levels. Ultrasonic energy couples to the nuclear spin system via spin-phonon interaction. The resulting nuclear acoustic resonance can be detected via the changes in (a) ultrasonic attenuation, (b) ultrasonic velocity, (c) material magnetization, (d) or nuclear magnetic susceptibility, all of which carries ''intrinsic and unique signatures'' of the material under investigation. The device's sensitivity and penetration depth (into metals) will be enhanced by incorporating SQUID technology into the design. We will present the details of interaction physics and outline a plan of action needed to successfully transform the concepts into a practical detector.
Date: April 11, 2002
Creator: Ze, F; Tittmann, B R & Lehahan, P M
Object Type: Article
System: The UNT Digital Library
Simulations of Boundary Turbulence in Tokamak Experiments (open access)

Simulations of Boundary Turbulence in Tokamak Experiments

Comparisons between the boundary plasma turbulence observed in the BOUT code and experiments on C-Mod, NSTX, and DIII-D are presented. BOUT is a 3D non-local electromagnetic turbulence simulation code which models boundary-plasma turbulence in a realistic divertor geometry using the modified Braginskii equations for plasma vorticity, density, the electron and ion temperatures and parallel momenta. Many features of the Quasi-Coherent (QC) mode, observed at high densities during enhanced D-alpha (EDA) H-Mode in Alcator C-Mod, are reproduced in BOUT simulations. The spatial structure of boundary plasma turbulence as observed by gas puff imaging (GPI) from discharges on NSTX and C-Mod are in general (NSTX) to good (CMod) agreement with BOUT simulations. Finally, BOUT simulations of DIII-D L-mode experiments near the Hmode transition threshold are in broad agreement with the experimental results.
Date: October 11, 2002
Creator: Nevins, W. M.; Xu, X. Q.; Carlstrom, T. N.; Cohen, R. H.; Groebner, R.; Jennings, T. et al.
Object Type: Article
System: The UNT Digital Library
Kull ALE: I. Unstructured Mesh Advection, Interface Capturing, and Multiphase 2T RHD with Material Interfaces (open access)

Kull ALE: I. Unstructured Mesh Advection, Interface Capturing, and Multiphase 2T RHD with Material Interfaces

Several advection algorithms are presented within the remap framework for unstructured mesh ALE codes. The methods discussed include a generic advection scheme based on a finite volume approach, and three groups of algorithms for the treatment of material boundary interfaces. The interface capturing algorithms belong to the Volume of Fluid (VoF) class of methods to approximate material interfaces from the local fractional volume of fluid distribution in arbitrary unstructured polyhedral meshes appropriate for the Kull code. Also presented are several schemes for extending single material radiation diffusion solvers to account for multi-material interfaces.
Date: February 11, 2002
Creator: Anninos, P
Object Type: Report
System: The UNT Digital Library
Autonomous Pathogen Detection System FY02 Annual Progress Report (open access)

Autonomous Pathogen Detection System FY02 Annual Progress Report

The objective of this project is to design, fabricate and field demonstrate a biological agent detection and identification capability, the Autonomous Pathogen Detector System (APDS). Integrating a flow cytometer and real-time polymerase chain reaction (PCR) detector with sample collection, sample preparation and fluidics will provide a compact, autonomously operating instrument capable of simultaneously detecting multiple pathogens and/or toxins. The APDS will operate in fixed locations, continuously monitoring air samples and automatically reporting the presence of specific biological agents. The APDS will utilize both multiplex immunoassays and nucleic acid assays to provide ''quasi-orthogonal'' multiple agent detection approaches to minimize false positives and increase the reliability of identification. Technical advances across several fronts must occur, however, to realize the full extent of the APDS. The end goal of a commercially available system for civilian biological weapon defense will be accomplished through three progressive generations of APDS instruments. The APDS is targeted for civilian applications in which the public is at high risk of exposure to covert releases of bioagent, such as major subway systems and other transportation terminals, large office complexes and convention centers. APDS is also designed to be part of a monitoring network of sensors integrated with command and control …
Date: November 11, 2002
Creator: Colston, B.; Brown, S.; Burris, K.; Elkin, C.; Hindson, B.; Langlois, R. et al.
Object Type: Report
System: The UNT Digital Library
Current Status and Future Technical Challenges for Tokamak Magnets (open access)

Current Status and Future Technical Challenges for Tokamak Magnets

Magnet technology for fusion in the last decade has been focusing mostly on the development of magnets for tokamaks--the most advanced fusion concept at the moment. The largest and the most complex tokamak under development is ITER. To demonstrate adequate design approaches to large magnets for ITER and to develop industrial capabilities, two large model coils and three insert coils, all using full-scale conductor, were built and tested by the international collaboration during 1994-2002. The status of the magnet technology and directions of future developments are discussed in this paper.
Date: November 11, 2002
Creator: Martovetsky, N.; Minervini, J.; Okuno, K.; Salpiero, E. & Filatov, O.
Object Type: Article
System: The UNT Digital Library
Woelter Instrument-Optical Design (open access)

Woelter Instrument-Optical Design

Hundreds of target assemblies will be constructed annually for use on NIF or OMEGA in the near future. Currently, we do not have the capability to tomographically characterize the target assemblies at the desired resolution. Hence, we cannot verify if an assembly has been assembled correctly. The Engineering Directorate, through the LDRD program, is currently funding an x-ray instruments that could solve this problem. This instrument is based on a Woelter [1] Type-I design. We will refer to this design as the Woelter instrument in the remainder of the report. Ideally, the Woelter instrument will create images with sub-micrometer resolution. Moreover, the instrument will have a field-of-view large enough to cover an entire target assembly (up to a 2 mm square), which would eliminate the need to take multiple radiographs to get one complete target image. This report describes the optical design of the Woelter instrument.
Date: October 11, 2002
Creator: Nederbragt, W. W.
Object Type: Report
System: The UNT Digital Library
Grid and Zone Selection for AMR and ALE Schemes (open access)

Grid and Zone Selection for AMR and ALE Schemes

Numerical algorithms are based fundamentally on polynomial interpolation. In regions of the computational domain where a low order polynomial fits the data well one will find small errors in the computed quantities. Therefore, in order to design robust methods for grid selection for AMR schemes or zone selection for ALE schemes, one needs some information on the local polynomial structure of the fields being computed. We provide here algorithms and software for selecting zones based on local estimates of polynomial interpolation error. The algorithms are based on multiresolution and wavelet analysis.
Date: September 11, 2002
Creator: Jameson, L; Johnson, J; Bihari, B; Eliason, D & Peyser, T
Object Type: Report
System: The UNT Digital Library
Methods for Mitigating Growth of Laser-Initiated Surface Damage on DKDP Optics at 351nm (open access)

Methods for Mitigating Growth of Laser-Initiated Surface Damage on DKDP Optics at 351nm

We report an experimental investigation of mitigating surface damage growth at 351nm for machine-finished DKDP optics. The objective was to determine which methods could be applied to pre-initiated or retrieved-from-service optics, in order to stop further damage growth for large aperture DKDP optics used in high-peak-power laser applications. The test results, and the evaluation thereof, are presented for several mitigation methods applied to DKDP surface damage. The mitigation methods tested were CW-CO{sub 2} laser processing, aqueous wet-etching, short-pulse laser ablation, and micro-machining. We found that micro-machining, using a single crystal diamond tool to completely remove the damage pit, produces the most consistent results to halt the growth of surface damage on DKDP. We obtained the successful mitigation of laser-initiated surface damage sites as large as 0.14mm diameter, for up to 1000 shots at 351nm and fluences in the range of 2 to 13J/cm{sup 2}, {approx} 11ns pulse length. Data obtained to-date indicates that micro-machining is the preferred method to process large-aperture optics.
Date: October 11, 2002
Creator: Hrubesh, L. W.; Brusasco, R. B.; Grundler, W.; Norton, M. A.; Donohue, E. E.; Molander, W. A. et al.
Object Type: Article
System: The UNT Digital Library
Conversion of Surplus Energetic Materials to Higher Value Products. A New Production of TATB (open access)

Conversion of Surplus Energetic Materials to Higher Value Products. A New Production of TATB

The progression of this project from a general demilitarization activity to the development of a new production of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) is described. There are four major synthetic routes to TATB. Only one of these routes has been used in the industrial production of TATB. There is a need to replace this route, which employs relatively harsh reaction conditions (elevated temperatures, strong acid) and a halocarbon starting material, with a less expensive and more environmentally friendly process. The Livermore process, which uses chemistry based on the vicarious nucleophilic substitution (VNS) of hydrogen and employment of relatively inexpensive feedstocks, is described and compared with other routes to TATB. Process development studies and the issue of TATB purification are also discussed.
Date: July 11, 2002
Creator: Mitchell, A. R.; Coburn, M. D.; Schmidt, R. D.; Pagoria, P. F. & Lee, G. S.
Object Type: Article
System: The UNT Digital Library