Mesoscale Simulations of a Wind Ramping Event for Wind Energy Prediction (open access)

Mesoscale Simulations of a Wind Ramping Event for Wind Energy Prediction

Ramping events, or rapid changes of wind speed and wind direction over a short period of time, present challenges to power grid operators in regions with significant penetrations of wind energy in the power grid portfolio. Improved predictions of wind power availability require adequate predictions of the timing of ramping events. For the ramping event investigated here, the Weather Research and Forecasting (WRF) model was run at three horizontal resolutions in 'mesoscale' mode: 8100m, 2700m, and 900m. Two Planetary Boundary Layer (PBL) schemes, the Yonsei University (YSU) and Mellor-Yamada-Janjic (MYJ) schemes, were run at each resolution as well. Simulations were not 'tuned' with nuanced choices of vertical resolution or tuning parameters so that these simulations may be considered 'out-of-the-box' tests of a numerical weather prediction code. Simulations are compared with sodar observations during a wind ramping event at a 'West Coast North America' wind farm. Despite differences in the boundary-layer schemes, no significant differences were observed in the abilities of the schemes to capture the timing of the ramping event. As collaborators have identified, the boundary conditions of these simulations probably dominate the physics of the simulations. They suggest that future investigations into characterization of ramping events employ ensembles of …
Date: September 21, 2011
Creator: Rhodes, M & Lundquist, J K
Object Type: Report
System: The UNT Digital Library
Commnity Petascale Project for Accelerator Science And Simulation: Advancing Computational Science for Future Accelerators And Accelerator Technologies (open access)

Commnity Petascale Project for Accelerator Science And Simulation: Advancing Computational Science for Future Accelerators And Accelerator Technologies

The design and performance optimization of particle accelerators are essential for the success of the DOE scientific program in the next decade. Particle accelerators are very complex systems whose accurate description involves a large number of degrees of freedom and requires the inclusion of many physics processes. Building on the success of the SciDAC-1 Accelerator Science and Technology project, the SciDAC-2 Community Petascale Project for Accelerator Science and Simulation (ComPASS) is developing a comprehensive set of interoperable components for beam dynamics, electromagnetics, electron cooling, and laser/plasma acceleration modelling. ComPASS is providing accelerator scientists the tools required to enable the necessary accelerator simulation paradigm shift from high-fidelity single physics process modeling (covered under SciDAC1) to high-fidelity multiphysics modeling. Our computational frameworks have been used to model the behavior of a large number of accelerators and accelerator R&D experiments, assisting both their design and performance optimization. As parallel computational applications, the ComPASS codes have been shown to make effective use of thousands of processors.
Date: October 21, 2011
Creator: Spentzouris, Panagiotis; /Fermilab; Cary, John; /Tech-X, Boulder; Mcinnes, Lois Curfman; /Argonne et al.
Object Type: Article
System: The UNT Digital Library
Final Technical Report (open access)

Final Technical Report

This report summarizes many of the projects, and lists all of the publications and persons trained with support from the grant.
Date: April 21, 2011
Creator: Herrin, David L.
Object Type: Report
System: The UNT Digital Library
Recommendations for a Static Cosmic Ray Shield for Enriched Germanium Detectors (open access)

Recommendations for a Static Cosmic Ray Shield for Enriched Germanium Detectors

This document provides a detailed study of cost and materials that could be used to shield the detector material of the international Tonne-scale germanium neutrinoless double-beta decay experiment from hadronic particles from cosmic ray showers at the Earth's surface. This work was motivated by the need for a shield that minimizes activation of the enriched germanium during storage; in particular, when the detector material is being worked on at the detector manufacturer's facility. This work considers two options for shielding the detector material from cosmic ray particles. One option is to use a pre-existing structure already located near the detector manufacturer, such as Canberra Industries in Meriden, Connecticut. The other option is to build a shield onsite at a detector manufacturer's site. This paper presents a cost and efficiency analysis of such construction.
Date: September 21, 2011
Creator: Aguayo Navarrete, Estanislao; Orrell, John L.; Ankney, Austin S. & Berguson, Timothy J.
Object Type: Report
System: The UNT Digital Library
Final Progress Report (open access)

Final Progress Report

The objective of this project was to complete the specifications and drawings for a variable speed kitchen exhaust system and the boiler heating system which when implemented will improve the heating efficiency of the building. The design work was focused in two key areas: kitchen ventilation and heating for the Ernie Turner Center building (ETC). RSA completed design work and issued a set of 100% drawings. RSA also worked with a cost estimator to put together a detailed cost estimate for the project. The design components are summarized.
Date: March 21, 2011
Creator: Fredeen, Amy
Object Type: Text
System: The UNT Digital Library
Clouds and Chemistry in the Atmosphere of Extrasolar Planet HR8799b (open access)

Clouds and Chemistry in the Atmosphere of Extrasolar Planet HR8799b

Using the integral field spectrograph OSIRIS, on the Keck II telescope, broad near-infrared H and K-band spectra of the young exoplanet HR8799b have been obtained. In addition, six new narrow-band photometric measurements have been taken across the H and K bands. These data are combined with previously published photometry for an analysis of the planet's atmospheric properties. Thick photospheric dust cloud opacity is invoked to explain the planet's red near-IR colors and relatively smooth near-IR spectrum. Strong water absorption is detected, indicating a Hydrogen-rich atmosphere. Only weak CH{sub 4} absorption is detected at K band, indicating efficient vertical mixing and a disequilibrium CO/CH{sub 4} ratio at photospheric depths. The H-band spectrum has a distinct triangular shape consistent with low surface gravity. New giant planet atmosphere models are compared to these data with best fitting bulk parameters, T{sub eff} = 1100K {+-} 100 and log(g) = 3.5 {+-} 0.5 (for solar composition). Given the observed luminosity (log L{sub obs}/L{sub {circle_dot}} {approx} -5.1), these values correspond to a radius of 0.75 R{sub Jup{sub 0.12}{sup +0.17}} and mass {approx} 0.72 M{sub Jup{sub -0.6}{sup +2.6}} - strikingly inconsistent with interior/evolution models. Enhanced metallicity (up to {approx} 10 x that of the Sun) along with …
Date: March 21, 2011
Creator: Barman, T. S.; Macintosh, B. A.; Konopacky, Q. M. & Marois, C.
Object Type: Article
System: The UNT Digital Library
DUK - A Fast and Efficient Kmer Based Sequence Matching Tool (open access)

DUK - A Fast and Efficient Kmer Based Sequence Matching Tool

A new tool, DUK, is developed to perform matching task. Matching is to find whether a query sequence partially or totally matches given reference sequences or not. Matching is similar to alignment. Indeed many traditional analysis tasks like contaminant removal use alignment tools. But for matching, there is no need to know which bases of a query sequence matches which position of a reference sequence, it only need know whether there exists a match or not. This subtle difference can make matching task much faster than alignment. DUK is accurate, versatile, fast, and has efficient memory usage. It uses Kmer hashing method to index reference sequences and Poisson model to calculate p-value. DUK is carefully implemented in C++ in object oriented design. The resulted classes can also be used to develop other tools quickly. DUK have been widely used in JGI for a wide range of applications such as contaminant removal, organelle genome separation, and assembly refinement. Many real applications and simulated dataset demonstrate its power.
Date: March 21, 2011
Creator: Li, Mingkun; Copeland, Alex & Han, James
Object Type: Article
System: The UNT Digital Library
DOE-ER-46139-Phase II-Final-Report-Tritt-2011 (open access)

DOE-ER-46139-Phase II-Final-Report-Tritt-2011

This proposal emphasizes investigations of the thermal and electrical transport properties of new and novel solid-state materials, with the specific goal of achieving higher efficiency solid-state thermoelectric materials. This program will continue to build a very strong collaborative research effort between researchers at Oak Ridge National Laboratory (ONRL) and Clemson University. We propose three new faculty hires and major equipment purchases in order to further enhance our level of national recognition. We will be positioned for competition for major non-EPSCoR DOE and DOD funding (i.e. NSF-Materials Research Center) and able to address many other areas of DOE and national importance. Graduate and undergraduate students will be extensively involved in this project, spending significant time at ORNL, thus gaining important training and educational opportunities. We will also include an outreach program to bring in outside students and faculty. An External Advisory Board of distinguished scientists will provide oversight to the program.
Date: October 21, 2011
Creator: Tritt, Terry M.
Object Type: Report
System: The UNT Digital Library
EMP Attachment 3 DOE-SC PNNL Site Dose Assessment Guidance (open access)

EMP Attachment 3 DOE-SC PNNL Site Dose Assessment Guidance

This Dose Assessment Guidance (DAG) describes methods to use to determine the Maximally-Exposed Individual (MEI) location and to estimate dose impact to that individual under the U.S. Department of Energy Office of Science (DOE-SC) Pacific Northwest National Laboratory (PNNL) Site Environmental Monitoring Plan (EMP). This guidance applies to public dose from radioactive material releases to the air from PNNL Site operations. This document is an attachment to the Pacific Northwest National Laboratory (PNNL) Environmental Monitoring Plan (EMP) and describes dose assessment guidance for radiological air emissions. The impact of radiological air emissions from the U.S. Department of Energy Office of Science (DOE-SC) PNNL Site is indicated by dose estimates to a maximally exposed member of the public, referred to as the maximally exposed individual (MEI). Reporting requirements associated with dose to members of the public from radiological air emissions are in 40 CFR Part 61.94, WAC 246-247-080, and DOE Order 458.1. The DOE Order and state standards for dose from radioactive air emissions are consistent with U.S. Environmental Protection Agency (EPA) dose standards in 40 CFR 61.92 (i.e., 10 mrem/yr to a MEI). Despite the fact that the current Contract Requirements Document (CRD) for the DOE-SC PNNL Site operations does …
Date: December 21, 2011
Creator: Snyder, Sandra F.
Object Type: Report
System: The UNT Digital Library
NSTX Plasma Response to Lithium Coated Divertor (open access)

NSTX Plasma Response to Lithium Coated Divertor

NSTX experiments have explored lithium evaporated on a graphite divertor and other plasma facing components in both L- and H- mode confinement regimes heated by high-power neutral beams. Improvements in plasma performance have followed these lithium depositions, including a reduction and eventual elimination of the HeGDC time between discharges, reduced edge neutral density, reduced plasma density, particularly in the edge and the SOL, increased pedestal electron and ion temperature, improved energy confinement and the suppression of ELMs in the H-mode. However, with improvements in confinement and suppression of ELMs, there was a significant secular increase in the effective ion charge Zeff and the radiated power in H-mode plasmas as a result of increases in the carbon and medium-Z metallic impurities. Lithium itself remained at a very low level in the plasma core, <0.1%. Initial results are reported from operation with a Liquid Lithium Divertor (LLD) recently installed.
Date: January 21, 2011
Creator: Kugel, H. W.; Bell, M. G.; Allain, J. P.; Bell, R. E.; Ding, S.; Gerhardt, S. P. et al.
Object Type: Report
System: The UNT Digital Library
New Low Emittance Lattice for the Super-B Accelerator (open access)

New Low Emittance Lattice for the Super-B Accelerator

New low emittance lattices have been designed for the asymmetric SuperB accelerator, aiming at a luminosity of 10{sup 36} cm{sup -2} s{sup -1}. Main optics features are two alternating arc cells with different horizontal phase advance, decreasing beam emittance and allowing at the same time for easy chromaticity correction in the arcs. Emittance can be further reduced by a factor of two for luminosity upgrade. Spin rotation schemes for the e{sup -} beam have been studied to provide longitudinal polarization at the IP, and implementation into the lattice is in progress.
Date: October 21, 2011
Creator: Biagini, M.E.; Boscolo, M.; Raimondi, P.; Tomassini, S.; Zobov, M.; /Frascati et al.
Object Type: Article
System: The UNT Digital Library
Techniques For Injection Of Pre-Charaterized Dust Into The Scrape Off Layer Of Fusion Plasma (open access)

Techniques For Injection Of Pre-Charaterized Dust Into The Scrape Off Layer Of Fusion Plasma

Introduction of micron-sized dust into the scrape-off layer (SOL) of a plasma has recently found many applications aimed primarily at determining dust behavior in future fusion reactors. The dust particles are typically composed of materials intrinsic to a fusion reactor. On DIII-D and TEXTOR carbon dust has been introduced into the SOL using a probe inserted from below into the divertor region. On NSTX, both Li and tungsten dust have been dropped from the top of the machine into the SOL throughout the duration of a discharge, by utilizing a vibrating piezoelectric based particle dropper. The original particle dropper was developed to inject passivated Li powder {approx} 40 {mu}m in diameter into the SOL to enhance plasma performance. A simplified version of the dropper was developed to introduce trace amounts of tungsten powder for only a few discharges, thus not requiring a large powder reservoir. The particles emit visible light from plasma interactions and can be tracked by either spectroscopic means or by fast frame rate visible cameras. This data can then be compared with dust transport codes such as DUSTT to make predictions of dust behavior in next-step devices such as ITER. For complete modeling results, it is desired …
Date: July 21, 2011
Creator: Roquemore, A. L.; John, B.; Friesen, F.; Hartzfeld, K. & Mansfield, D. K.
Object Type: Report
System: The UNT Digital Library
Gyrokinetics Simulation of Energetic Particle Turbulence and Transport (open access)

Gyrokinetics Simulation of Energetic Particle Turbulence and Transport

Progress in research during this year elucidated the physics of precession resonance and its interaction with radial scattering to form phase space density granulations. Momentum theorems for drift wave-zonal flow systems involving precession resonance were derived. These are directly generalizable to energetic particle modes. A novel nonlinear, subcritical growth mechanism was identified, which has now been verified by simulation. These results strengthen the foundation of our understanding of transport in burning plasmas
Date: September 21, 2011
Creator: Diamond, Patrick H.
Object Type: Report
System: The UNT Digital Library
DuraLith Alkali-Aluminosilicate Geopolymer Waste Form Testing for Hanford Secondary Waste (open access)

DuraLith Alkali-Aluminosilicate Geopolymer Waste Form Testing for Hanford Secondary Waste

The primary objective of the work reported here was to develop additional information regarding the DuraLith alkali aluminosilicate geopolymer as a waste form for liquid secondary waste to support selection of a final waste form for the Hanford Tank Waste Treatment and Immobilization Plant secondary liquid wastes to be disposed in the Integrated Disposal Facility on the Hanford Site. Testing focused on optimizing waste loading, improving waste form performance, and evaluating the robustness of the waste form with respect to waste variability.
Date: July 21, 2011
Creator: Gong, W. L.; Lutz, Werner & Pegg, Ian L.
Object Type: Report
System: The UNT Digital Library
Expanded High-Level Waste Glass Property Data Development: Phase I (open access)

Expanded High-Level Waste Glass Property Data Development: Phase I

Two separate test matrices were developed as part if the EM-21 Glass Matrix Crucible Testing. The first matrix, developed using a single component-at-a-time design method and covering glasses of interest primarily to Hanford, is addressed in this data package. This data package includes methods and results from glass fabrication, chemical analysis of glass compositions, viscosity, electrical conductivity, liquidus temperature, canister centerline cooling, product consistency testing, and the toxicity characteristic leach procedure.
Date: January 21, 2011
Creator: Schweiger, Michael J.; Riley, Brian J.; Crum, Jarrod V.; Hrma, Pavel R.; Rodriguez, Carmen P.; Arrigoni, Benjamin M. et al.
Object Type: Report
System: The UNT Digital Library
FY 2011 4th Quarter Metric: Estimate of Future Aerosol Direct and Indirect Effects (open access)

FY 2011 4th Quarter Metric: Estimate of Future Aerosol Direct and Indirect Effects

The global and annual mean aerosol direct and indirect effects, relative to 1850 conditions, estimated from CESM simulations are 0.02 W m-2 and -0.39 W m-2, respectively, for emissions in year 2100 under the IPCC RCP8.5 scenario. The indirect effect is much smaller than that for 2000 emissions because of much smaller SO2 emissions in 2100; the direct effects are small due to compensation between warming by black carbon and cooling by sulfate.
Date: September 21, 2011
Creator: Koch, D.
Object Type: Text
System: The UNT Digital Library
Study of wavelength-shifting chemicals for use in large-scale water Cherenkov detectors (open access)

Study of wavelength-shifting chemicals for use in large-scale water Cherenkov detectors

Cherenkov detectors employ various methods to maximize light collection at the photomultiplier tubes (PMTs). These generally involve the use of highly reflective materials lining the interior of the detector, reflective materials around the PMTs, or wavelength-shifting sheets around the PMTs. Recently, the use of water-soluble wavelength-shifters has been explored to increase the measurable light yield of Cherenkov radiation in water. These wave-shifting chemicals are capable of absorbing light in the ultravoilet and re-emitting the light in a range detectable by PMTs. Using a 250 L water Cherenkov detector, we have characterized the increase in light yield from three compounds in water: 4-Methylumbelliferone, Carbostyril-124, and Amino-G Salt. We report the gain in PMT response at a concentration of 1 ppm as: 1.88 {+-} 0.02 for 4-Methylumbelliferone, stable to within 0.5% over 50 days, 1.37 {+-} 0.03 for Carbostyril-124, and 1.20 {+-} 0.02 for Amino-G Salt. The response of 4-Methylumbelliferone was modeled, resulting in a simulated gain within 9% of the experimental gain at 1 ppm concentration. Finally, we report an increase in neutron detection performance of a large-scale (3.5 kL) gadolinium-doped water Cherenkov detector at a 4-Methylumbelliferone concentration of 1 ppm.
Date: September 21, 2011
Creator: Sweany, M; Bernstein, A; Dazeley, S; Dunmore, J; Felde, J; Svoboda, R et al.
Object Type: Article
System: The UNT Digital Library
Portal 6.0 Released!! (open access)

Portal 6.0 Released!!

None
Date: March 21, 2011
Creator: Cantor, Michael & Smirnova, Tatyana
Object Type: Article
System: The UNT Digital Library
Department of Energy – Office of Science Pacific Northwest Site Office Environmental Monitoring Plan for the DOE-SC PNNL Site (open access)

Department of Energy – Office of Science Pacific Northwest Site Office Environmental Monitoring Plan for the DOE-SC PNNL Site

The Pacific Northwest Site Office (PNSO) manages the contract for operations at the U.S. Department of Energy Office of Science (DOE-SC) Pacific Northwest National Laboratory (PNNL) Site in Richland, Washington. Radiological operations at the DOE-SC PNNL Site expanded in 2010 with the completion of facilities at the Physical Sciences Facility. As a result of the expanded radiological work at the site, the Washington State Department of Health (WDOH) has required that offsite environmental surveillance be conducted as part of the PNNL Site Radioactive Air Emissions License. The environmental monitoring and surveillance requirements of various orders, regulations, and guidance documents consider emission levels and subsequent risk of negative human and environmental impacts. This Environmental Monitoring Plan (EMP) describes air surveillance activities at the DOE-SC PNNL Site. The determination of offsite environmental surveillance needs evolved out of a Data Quality Objectives process (Barnett et al. 2010) and Implementation Plan (Snyder et al. 2010). The entire EMP is a compilation of several documents, which include the Main Document (this text), Attachment 1: Sampling and Analysis Plan, Attachment 2: Data Management Plan, and Attachment 3: Dose Assessment Guidance.
Date: December 21, 2011
Creator: Snyder, Sandra F.; Meier, Kirsten M.; Barnett, J. M.; Bisping, Lynn E.; Poston, Ted M. & Rhoads, Kathleen
Object Type: Report
System: The UNT Digital Library
Implications of Pulser Voltage Ripple (open access)

Implications of Pulser Voltage Ripple

In a recent set of measurements obtained by G. Kamin, W. Manning, A. Molvik, and J. Sullivan, the voltage waveform of the diode pulser had a ripple of approximately {+-}1.3% of the 65 kV flattop voltage, and the beam current had a larger corresponding ripple of approximately {+-}8.4% of the 1.5 mA average current at the location of the second Faraday cup, approximately 1.9 m downstream from the ion source. The period of the ripple was about 1 {mu}s. It was initially unclear whether this large current ripple was in fact a true measurement of the current or a spurious measurement of noise produced by the pulser electronics. The purpose of this note is to provide simulations which closely match the experimental results and thereby corroborate the physical nature of those measurements, and to provide predictions of the amplitude of the current ripples as they propagate to the end of linear transport section. Additionally analytic estimates are obtained which lend some insight into the nature of the current fluctuations and to provide an estimate of what the maximum amplitude of the current fluctuations are expected to be, and conversely what initial ripple in the voltage source is allowed, given a …
Date: December 21, 2011
Creator: Barnard, J J
Object Type: Report
System: The UNT Digital Library
Annual Report of Groundwater Monitoring at Everest, Kansas, in 2010. (open access)

Annual Report of Groundwater Monitoring at Everest, Kansas, in 2010.

The Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) began its environmental investigations at Everest, Kansas, in 2000. The work at Everest is implemented on behalf of the CCC/USDA by Argonne National Laboratory, under the oversight of the Kansas Department of Health and Environment (KDHE). The results of the environmental investigations have been reported in detail (Argonne 2001, 2003, 2006a,b). The lateral extent of the carbon tetrachloride in groundwater over the years of investigation has been interpreted as shown in Figure 1.1 (2001-2002 data), Figure 1.2 (2006 data), Figure 1.3 (2008 data), and Figure 1.4 (2009 data). The pattern of groundwater flow and inferred contaminant migration has consistently been to the north-northwest from the former CCC/USDA facility toward the Nigh property, and then west-southwest from the Nigh property (e.g., Figure 1.5 [2008 data] and Figure 1.6 [2009 data]). Both the monitoring data for carbon tetrachloride and the low groundwater flow rates estimated for the Everest aquifer unit (Argonne 2003, 2006a,b, 2008) indicate slow contaminant migration. On the basis of the accumulated findings, in March 2009 the CCC/USDA developed a plan for annual monitoring of the groundwater and surface water. This current monitoring plan (Appendix A in the report …
Date: March 21, 2011
Creator: Lafreniere, L. M.
Object Type: Report
System: The UNT Digital Library
Tests of Radiation-Hard Silicon Microstrip Sensors for CMS in S-LHC (open access)

Tests of Radiation-Hard Silicon Microstrip Sensors for CMS in S-LHC

The tests are to study the performance of various silicon microstrip sensors that are sufficiently radiation-hard to be considered as candidates for the CMS outer (R &gt; 25cm) tracker in the second phase of the currently envisioned S-LHC upgrade. The main goal of the beam test is to test Float Zone (FZ) and Magnetic Czochralski (MCz) silicon sensors that have been procured from Hamamatsu by the CMS collaboration as possible replacements for the CMS outer tracker for phase 2 operations. The detectors under test (DUT) will be isntalled in a cold box that contains 10 slots for modules based on CMS Tracker hybrids. Slots 1-4 and 7-10 are occupied by reference planes and slots 5 and 6 are reserved for DUTs. The box is cooled by Peltier elements in thermal contact with the top and bottom aluminum baseplates and is typically operated at around -25 C. A PCI based version of the CMS DAQ is used to read out the 10 slots based on triggers provided by beam scintillation counters. Given the low rate of beam particles the hybrid APVs will be operated in Peak mode, which maximizes the signal-to-noise performance of the readout chips. The internal clock operates at …
Date: February 21, 2011
Creator: Luukka, Panja; Maenpaa, Teppo; Tuovinen, Esa; Spiegel, Lenny & Flight, Robert
Object Type: Report
System: The UNT Digital Library
Distinguishing Realistic Military Blasts from Firecrackers in Mitigation Studies of Blast Induced Traumatic Brain Injury (open access)

Distinguishing Realistic Military Blasts from Firecrackers in Mitigation Studies of Blast Induced Traumatic Brain Injury

In their Contributed Article, Nyein et al. (1,2) present numerical simulations of blast waves interacting with a helmeted head and conclude that a face shield may significantly mitigate blast induced traumatic brain injury (TBI). A face shield may indeed be important for future military helmets, but the authors derive their conclusions from a much smaller explosion than typically experienced on the battlefield. The blast from the 3.16 gm TNT charge of (1) has the following approximate peak overpressures, positive phase durations, and incident impulses (3): 10 atm, 0.25 ms, and 3.9 psi-ms at the front of the head (14 cm from charge), and 1.4 atm, 0.32 ms, and 1.7 psi-ms at the back of a typical 20 cm head (34 cm from charge). The peak pressure of the wave decreases by a factor of 7 as it traverses the head. The blast conditions are at the threshold for injury at the front of the head, but well below threshold at the back of the head (4). The blast traverses the head in 0.3 ms, roughly equal to the positive phase duration of the blast. Therefore, when the blast reaches the back of the head, near ambient conditions exist at the …
Date: January 21, 2011
Creator: Moss, W C; King, M J & Blackman, E G
Object Type: Article
System: The UNT Digital Library
Programmable Beam Spatial Shaping System for the National Ignition Facility (open access)

Programmable Beam Spatial Shaping System for the National Ignition Facility

A system of customized spatial light modulators has been installed onto the front end of the laser system at the National Ignition Facility (NIF). The devices are capable of shaping the beam profile at a low-fluence relay plane upstream of the amplifier chain. Their primary function is to introduce 'blocker' obscurations at programmed locations within the beam profile. These obscurations are positioned to shadow small, isolated flaws on downstream optical components that might otherwise limit the system operating energy. The modulators were designed to enable a drop-in retrofit of each of the 48 existing Pre Amplifier Modules (PAMs) without compromising their original performance specifications. This was accomplished by use of transmissive Optically Addressable Light Valves (OALV) based on a Bismuth Silicon Oxide photoconductive layer in series with a twisted nematic liquid crystal (LC) layer. These Programmable Spatial Shaper packages in combination with a flaw inspection system and optic registration strategy have provided a robust approach for extending the operational lifetime of high fluence laser optics on NIF.
Date: January 21, 2011
Creator: Heebner, J.; Borden, M.; Miller, P.; Hunter, S.; Christensen, K.; Scanlan, M. et al.
Object Type: Article
System: The UNT Digital Library