The monochromatic opacity, {kappa}{sub v}, quantifies the property of a material to remove energy of frequency v from a radiation field. A harmonic average of {kappa}{sub v}, known as the Rosseland mean, {kappa}{sub R}, is frequently used to simplify the calculation of energy transport in stars. The term ''opacity'' is commonly understood to refer to {kappa}{sub R}. Opacity plays an important role in stellar modeling because for most stars radiation is the primary mechanism for transporting energy from the nuclear burning region in the core to the surface. Depending on the mass, convection and electron thermal conduction can also be important modes of stellar energy transport. The efficiency of energy transport is related to the temperature gradient, which is directly proportional to the mean radiative opacity in radiation dominated regions. When the radiative opacity is large, convection can become the more efficient energy transport mechanism. Electron conductive opacity, the resistance of matter to thermal conduction, is inversely proportional to electron thermal conductivity. Thermal conduction becomes the dominant mode of energy transport at high density and low temperature.

Issues related to the growth of nitride-based UV emitters are investigated in this work. More than 100 times of improved in the optical efficiency of the GaN active region can be attained with a combination of raising the growth pressure and introducing a small amount of indium. The unique issue in the UV emitter concerning the use of AlGaN for confinement and the associated tensile cracking is also investigated. They showed that the quaternary AlGaInN is potentially capable of providing confinement to GaN and GaN:In active regions while maintaining lattice matching to GaN, unlike the AlGaN ternary system.

We describe the microfabrication of an extremely compact optical system as a key element in an integrated capillary channel electrochromatograph with fluorescence detection. The optical system consists of a vertical cavity surface-emitting laser (VCSEL), two high performance microlenses and a commercial photodetector. The microlenses are multilevel diffractive optics patterned by electron beam lithography and etched by reactive ion etching in fused silica. The design uses substrate-mode propagation within the fused silica substrate. Two generations of optical subsystems are described. The first generation design has a 6 mm optical length and is integrated directly onto the capillary channel-containing substrate. The second generation design separates the optical system onto its own substrate module and the optical path length is further compressed to 3.5 mm. The first generation design has been tested using direct fluorescence detection with a 750 nm VCSEL pumping a 10{sup {minus}4}M solution of CY-7 dye. The observed signal-to-noise ratio of better than 100:1 demonstrates that the background signal from scattered pump light is low despite the compact size of the optical system and is adequate for system sensitivity requirements.

An analytical model of plasma flow from a metal plate hit by an intense, pulsed, electron beam aims to bridge the gap between radiation-hydrodynamics simulations and experiments, and to quantify the self-effect of the electron beam penetrating the flow. Does the flow disrupt the tight focus of the initial electron bunch, or later pulses in a train? This work aims to model the spatial distribution of plasma speed, density, degree of ionization, and magnetization to inquire. The initial solid density, several eV plasma expands to 1 cm and 10{sup {minus}4} relative density by 2 {micro}s, beyond which numerical simulations are imprecise. Yet, a Faraday cup detector at the ETA-II facility is at 25 cm from the target and observes the flow after 50 {micro}s. The model helps bridge this gap. The expansion of the target plasma into vacuum is so rapid that the ionized portion of the flow departs from local thermodynamic equilibrium. When the temperature (in eV) in a parcel of fluid drops below V{sub i} x [(2{gamma} - 2)/(5{gamma} + 17)], where V{sub i} is the ionization potential of the target metal (7.8 eV for tantalum), and {gamma} is the ratio of specific heats (5/3 for atoms), then …

The proposed Advanced Hydro Facility (AHF) is required to produce multi-pulse radiographs. Electron beam pulse machines with sub-microsecond repetition are not yet available to test the problem of electron beam propagation through the hydro-dynamically expanding plasma from the nearby previously heated target material. A proposed test scenario includes an ohmically heated small volume of target material simulating the electron beam heating, along with an actual electron beam pulse impinging on nearby target material. A pulse power heating circuit was tested to evaluate the limits of pulse heating a small volume of material to tens of kilo-joules per gram. The main pulse heating time (50 to 100 ns) was to simulate the electron beam heating of a converter target material. To avoid skin heating non-uniformity a longer time scale pulse of a few microseconds first heats the target material to a few thousand degrees near the liquid to vapor transition. Under this state the maximum electric field that the current carrying conductor can support is the important parameter for insuring that the 100 ns heating pulse can deposit sufficient power. A small pulse power system was built for tests of this limit. Under cold conditions the vacuum electric field hold-off limit …

In a quantum grid infrared photodetector (QGIP), the active multiple quantum well material is patterned into a grid structure. The purposes of the grid are on the one hand to create additional lateral electron confinement and on the other to convert part of the incident light into parallel propagation. With these two unique functions, a QGIP allows intersubband transition to occur in all directions. In this work, we focused on improving the effectiveness of a QGIP in redirecting the propagation of light using a blazed structure. The optimization of the grid parameters in terms of the blaze angle and the periodicity was performed by numerical simulation using the modal transmission-line theory and verified by experiment. With a blazed structure, the sensitivity of a QGIP can be improved by a factor of 1.8 compared with a regular QGIP with rectangular profiles.

A mechanically-induced color transition (''mechanochromism'') in polydiacetylene thin films has been generated at the nanometer scale using the tips of two different scanning probe microscopes. A blue-to-red chromatic transition in polydiacetylene molecular trilayer films, polymerized from 10,12-pentacosadiynoic acid (poly-PCDA), was found to result from shear forces acting between the tip and the poly-PCDA molecules, as independently observed with near-field scanning optical microscopy and atomic force microscopy (AFM). Red domains were identified by a fluorescence emission signature. Transformed regions as small as 30 nm in width were observed with AFM. The irreversibly transformed domains preferentially grow along the polymer backbone direction. Significant rearrangement of poly-PCDA bilayer segments is observed by AFM in transformed regions. The removal of these segments appears to be a characteristic feature of the transition. To our knowledge, this is the first observation of nanometer-scale mechanochromism in any material.

The Geothermal Drilling Organization (GDO), founded in 1982 as a joint Department of Energy (DOE)-Industry organization, develops and funds near-term technology development projects for reducing geothermal drilling costs. Sandia National Laboratories administers DOE funds to assist industry critical cost-shared projects and provides development support for each project. GDO assistance to industry is vital in developing products and procedures to lower drilling costs, in part, because the geothermal industry is small and represents a limited market.

Using Interracial Force Microscopy (IFM), we investigated the tribological behavior of hexadecanethiol monolayer on Au and films of octadecyltrichlorosilane (ODTS), perfluorodecyltrichlorosilane (PFTS) and dodecane on Si. We observe a strong correlation between hysteresis in a compression cycle (measured via nanoindentation) and friction. Additionally, we suggest that the amount of hysteresis and friction in each film is related to its detailed molecular structure, especially the degree of molecular packing.

The rutile TiO{sub 2} (110) (1x1) surface is considered the prototypical ''well-defined'' system in the surface science of metal oxides. Its popularity results partly from two experimental advantages: bulk-reduced single crystals do not exhibit charging, and stoichiometric surfaces--as judged by electron spectroscopes--can be prepared reproducibly by sputtering and annealing in oxygen. We present results that show that this commonly-applied preparation procedure may result in a surface structure that is by far more complex than generally anticipated. Flat, (1x1) terminated surfaces are obtained by sputtering and annealing in ultrahigh vacuum. When re-annealed in oxygen at moderate temperatures (470 K to 660 K), irregular networks of partially-connected, pseudohexagonal rosettes (6.5 x 6 {angstrom} wide), one-unit cell wide strands, and small ({approximately} tens of {angstrom}) (1x1) islands appear. This new surface phase is formed through reaction of oxygen gas with interstitial Ti from the reduced bulk. Because it consists of an incomplete, kinetically-limited (1x1) layer, this phenomenon has been termed restructuring. We report a combined experimental and theoretical study that systematically explores this restructuring process. The influence of several parameters (annealing time, temperature, pressure, sample history, gas) on the surface morphology is investigated using STM. The surface coverage of the added phase as …

Energy (DOE)-industry research and development (R and D) organization, sponsors near-term technology development projects for reducing geothermal drilling and well maintenance costs. Sandia National Laboratories (Albuquerque, NM) administers DOE funds for GDO cost-shared projects and provides technical support. The GDO serves a very important function in fostering geothermal development. It encourages commercialization of emerging, cost-reducing drilling technologies, while fostering a spirit of cooperation among various segments of the geothermal industry. For Sandia, the GDO also serves as a means of identifying the geothermal industry's drilling fuel/or well maintenance problems, and provides an important forum for technology transfer. Successfully completed GDO projects include: the development of a high-temperature borehole televiewer, high-temperature rotating head rubbers, a retrievable whipstock, and a high-temperature/high-pressure valve-changing tool. Ongoing GDO projects include technology for stemming lost circulation; foam cement integrity log interpretation, insulated drill pipe, percussive mud hammers for geothermal drilling, a high-temperature/ high-pressure valve changing tool assembly (adding a milling capability), deformed casing remediation, high- temperature steering tools, diagnostic instrumentation for casing in geothermal wells, and elastomeric casing protectors.

The increased demand for portable electronics has lead to the need for higher performance and efficiency. Devices operating at less than 50 {micro}W of power are defined as ultra-low-power (ULP) devices. New progress has been achieved on InP/InGaAs HBT and InAIAs/InGaAs HBT optimized for ULP applications. f{sub T} values of 2.2 GHz, and f{sub MAX} values of 20 GHz have been obtained for HBTs operating at less than 40 {micro}W. Current gain is greater than 45 with the device operating at less than 20 {micro}A on a 2.5 x 5 {micro}m{sup 2} device. These devices have been significantly improved over the previously reported MOCVD grown InP/InGaAs ULP HBT which has f{sub MAX} of 10 GHz operating in the ultra-low-power level. The improvements have been attributed to the reduction of base dopant diffusion associated with Zn doping.

This project has comprised design, analysis, laboratory testing, and field testing of insulated drill pipe (IDP). This paper will briefly describe the earlier work, but will focus on results from the recently-completed field test in a geothermal well. Field test results are consistent with earlier analyses and laboratory tests, all of which support the conclusion that insulated drill pipe can have a very significant effect on circulating fluid temperatures. This will enable the use of downhole motors and steering tools in hot wells, and will reduce corrosion, deterioration of drilling fluids, and heat-induced failures in other downhole components.

This paper addresses key issues for the cost-effective use of COTS microelectronics in radiation environments that enable circuit or system designers to manage risks and ensure mission success. COTS parts with low radiation tolerance should not be used when they degrade mission critical functions or lead to premature system failure. We review several factors and tradeoffs affecting the successful application of COTS parts including (1) hardness assurance and qualification issues, (2) system hardening techniques, and (3) life-cycle costs. The paper also describes several experimental studies that address trends in total-dose, transient, and single-event radiation hardness as COTS technology scales to smaller feature sizes. As an example, the level at which dose-rate upset occurs in Samsung SRAMS increases from 1.4x10{sup 8} rads(Si)/s for a 256K SRAM to 7.7x10{sup 9} rads(Si)/s for a 4M SRAM, indicating unintentional hardening improvements in the design or process of a commercial technology. Additional experiments were performed to quantify variations in radiation hardness for COTS parts. In one study, only small (10-15%) variations were found in the dose-rate upset and latchup thresholds for Samsung 4M SRAMS from three different date codes. In another study, irradiations of 4M SRAMS from Samsung, Hitachi, and Toshiba indicate large differences in …

MTI is a comprehensive research and development project that includes up-front modeling and analysis, satellite system design, fabrication, assembly and testing, on-orbit operations, and experimentation and data analysis. The satellite is designed to collect radiometrically calibrated, medium resolution imagery in 15 spectral bands ranging from 0.45 to 10.70 pm. The payload portion of the satellite includes the imaging system components, associated electronics boxes, and payload support structure. The imaging system includes a three-mirror anastigmatic off-axis telescope, a single cryogenically cooled focal plane assembly, a mechanical cooler, and an onboard calibration system. Payload electronic subsystems include image digitizers, real-time image compressors, a solid state recorder, calibration source drivers, and cooler temperature and vibration controllers. The payload support structure mechanically integrates all payload components and provides a simple four point interface to the spacecraft bus. All payload components have been fabricated and tested, and integrated.

The authors report spurious free dynamic range measurements of 850nm vertical cavity surface emitting lasers in short multimode links for radio frequency communication. For a 27m fiber link, the dynamic range at optimal bias was greater than 95dB-Hz{sup 2/3} for modulation frequencies between 1 and 5.5 GHz, which exceeds the requirements for antenna remoting in microcellular networks. In a free space link, they have measured the highest dynamic range in an 850nm vertical cavity surface emitting laser of 113dB-Hz{sup 2/3} at 900MHz. We have also investigated the effects of modal noise and differential mode delay on the dynamic range for longer lengths of fiber.

Laboratory experiments have been performed to evaluate the performance of a premixed low-swirl burner (LSB) in configurations that simulate commercial heating appliances. Laser diagnostics were used to investigate changes in flame stabilization mechanism, flowfield, and flame stability when the LSB flame was confined within quartz cylinders of various diameters and end constrictions. The LSB adapted well to enclosures without generating flame oscillations and the stabilization mechanism remained unchanged. The feasibility of using the LSB as a low NO{sub x} commercial burner has also been verified in a laboratory test station that simulates the operation of a water heater. It was determined that the LSB can generate NO{sub x} emissions < 10 ppm (at 3% O{sub 2}) without significant effect on the thermal efficiency of the conventional system. The study has demonstrated that the lean premixed LSB has commercial potential for use as a simple economical and versatile burner for many low emission gas appliances.

The authors describe a numerical scheme to solve 3D Arbitrary Lagrangian-Eulerian (ALE) hydrodynamics on an unstructured mesh using a discontinuous Galerkin method (DGM) and an explicit Runge-Kutta time discretization. Upwinding is achieved through Roe's linearized Riemann solver with the Harten-Hyman entropy fix. For stabilization, a 3D quadratic programming generalization of van Leer's 1D minmod slope limiter is used along with a Lapidus type artificial viscosity. This DGM scheme has been tested on a variety of hydrodynamic test problems and appears to be robust making it the basis for the integrated 3D inertial confinement fusion modeling code (ICF3D). For efficient code development, they use C++ object oriented programming to easily separate the complexities of an unstructured mesh from the basic physics modules. ICF3D is fully parallelized using domain decomposition and the MPI message passing library. It is fully portable. It runs on uniprocessor workstations and massively parallel platforms with distributed and shared memory.

The Main Injector (MI) supports the Tevatron Fixed Tar- get and Proton-Antiproton Collider modes of operation as well as providing 120 GeV/c resonantly extracted beam for the Main Injector Fixed Target Program. A set of beam transport lines, called Al and Pl, from the Main Injector converge on the injection point of the Tevatron, with the Al being used to transport 150 GeV/c antipro- tons (pbars) to the Tevatron. Pl is used to transport 150 GeV/c protons to the Tevatron, 120 GeV/c protons to the pbar target, and eventually 120 GeV/c resonantly ex- tracted protons to the existing Fixed Target areas. In ad- dition, the Pl line will be used to transport 8.9 GeV/c pbars from the Source back to the MI and recycled 150 GeV/c pbars at the end of Collider stores. In order to ac- complish the second and third function, the Pl beamline is continued beyond the Tevatron injection point in a sec- tion of the decommissioned Main Ring, called the P2 beamline. This transports the protons to a magnetic switch used to select either the modified transport line, used for targeting protons for pbar production, or the transport line which connects to the existing Fixed Target …

We present a measurement of the triple differential cross section for dijet production in proton-antiproton scattering at a center of mass energy of 1800 GeV. The data were taken with the D0 detector at the Fermilab Tevatron and are compared to next to leading order QCD theoretical predictions with differing parton distribution functions. The data are of sufficient accuracy to rule out or favor parton distribution functions over a wide range in x .

We used a fully coupled climate/chemistry model together with the newly developed IPCC anthropogenic emissions to simulate the climate variation by aerosols. The range of aerosol forcing by the primary indirect effect in next century is estimated between -0.49 and -1.20 W m{sup -2}. This range does not include the potential natural emissions feedbacks associated with climate change. Since sea salt emissions are projected to increase from 88.5 Tg of Na for 2000 to 155 Tg of Na for 2100, the increased aerosol forcing from emissions feedbacks would be mainly over the ocean in southern hemisphere where the maximum is located. More simulations will be performed in order to identify the emissions feedbacks from the total feedbacks. This will provide us a more quantitative range for the aerosol climate forcing as compared to those from greenhouse gases. The magnitudes of climate feedbacks calculated here are subject to uncertainties from climate system. Uncertainty can also arise from the model configuration where the sea surface temperatures are prescribed instead of using a mixed-layer ocean model or a full ocean general circulation model. To quantity these uncertainties, sensitivities tests will be performed in a future study.

The National Ignition Facility, or NIF, currently under construction at the Lawrence Livermore National Laboratory will contain the world's most powerful laser. By the year 2003 the NIF laser will be a research tool allowing scientists a glimpse into plasma interactions that are equivalent to those found in the center of the sun. Every eight hours the NIF will generate 1.8 MJ of 351-nm light carried by 192 pulsed laser beams and focus it onto a pea-sized target. This will result in a fusion reaction between two isotopes of hydrogen, creating for a few hundred picoseconds stellar conditions. Synchronizing the beams and diagnosing the fusion reaction requires generation and delivery of over 1000 precisely timed triggers to a multitude of systems. The NIF Integrated Timing System (ITS) was developed to provide reliable, accurately timed triggers that allow each client system to operate independently during periods of shot preparation and maintenance, yet be coordinated to a few tens of picoseconds during the experiment. The ITS applies technologies developed for fiber communications and Two-Way Time Transfer, and integrates them by way of a computer communications network to achieve distributed control, dynamically configurable coordination and independent among timing channels, and integrated self-diagnostics.

The operation of an ADT system with the associated nuclear reactions has a profound effect upon the chemistry of the fuel - especially with regards to container compatibility and the chemical separations that may be required. The container can be protected by maintaining the redox chemistry within a relatively narrow, non-corrosive window. Neutron economy as well as other factors require a sophisticated regime of fission product separations. Neither of these control requirements has been demonstrated on the scale or degree of sophistication necessary to support an ADT device. We review the present situation with respect to fluoride salts, and focus on the critical issues in these areas which must be addressed. One requirement for advancement in this area - a supply of suitable materials - will soon be fulfilled by the remediation of ORNL�s Molten Salt Reactor Experiment, and the removal of a total of 11,000 kg of enriched (Li-7 > 99.9%) coolant, flush, and fuel salts.

We have developed a process for the production of microchannel arrays on bonded glass substrates up to I4 x 58 cm, for DNA sequencing. Arrays of 96 and 384 microchannels, each 46 cm long have been built. This technology offers significant advantages over discrete capillaries or conventional slab-gel approaches. High throughput DNA sequencing with over 550 base pairs resolution has been achieved. With custom fabrication apparatus, microchannels are etched in a borosilicate substrate, and then fusion bonded to a top substrate 1.1 mm thick that has access holes formed in it. SEM examination shows a typical microchannel to be 40 x 180 micrometers by 46 cm Iong; the etch is approximately isotropic, leaving a key undercut, for forming a rounded channel. The surface roughness at the bottom of the 40 micrometer deep channel has been profilometer measured to be as low as 20 nm; the roughness at the top surface was 2 nm. Etch uniformity of about 5% has been obtained using a 22% vol. HF / 78% Acetic acid solution. The simple lithography, etching, and bonding of these substrates enables efficient production of these arrays and extremely precise replication From master masks and precision machining with a mandrel. Keywords: …