345 Matching Results

Search Results

Advanced search parameters have been applied.

Janus Intense Short Pulse (ISP), the Next Ultrahigh Intensity Laser at LLNL

Description: The Janus ISP upgrade is being developed at LLNL to provide a high-energy (hundreds of Joules) short duration (0.5 to 200 ps) laser pulse with variable delay from a second high-energy (up to 1kJ) long duration (0.2 to 20 ns) laser pulse on target. A new target chamber will allow the angle between the long and short pulse beams to be varied from about 35 to near 180 degrees. Commissioning of the system will begin in the summer of 2005.
Date: September 28, 2004
Creator: Caird, J A; Bonlie, J D; Britten, J A; Cross, R R; Ebbers, C A; Eckart, M J et al.
Partner: UNT Libraries Government Documents Department

Complete fabrication of target experimental chamber and implement initial target diagnostics to be used for the first target experiments in NDCX-1

Description: The Heavy Ion Fusion Science Virtual National Laboratory (HIFS-VNL) has completed the fabrication of a new experimental target chamber facility for future Warm Dense Matter (WDM) experiments, and implemented initial target diagnostics to be used for the first target experiments in NDCX-1. The target chamber has been installed on the NDCX-I beamline. This achievement provides to the HIFS-VNL unique and state-of-the-art experimental capabilities in preparation for the planned target heating experiments using intense heavy ion beams.
Date: June 9, 2008
Creator: Bieniosek, F.M.; Bieniosek, F.M.; Dickinson, M.R.; Henestroza, E.; Katayanagi, T.; Jung, J.Y. et al.
Partner: UNT Libraries Government Documents Department

Chamber Technology Concepts for Inertial Fusion Energy: Three Recent Examples

Description: The most serious challenges in the design of chambers for inertial fusion energy (IFE) are 1) protecting the first wall from fusion energy pulses on the order of several hundred megajoules released in the form of x rays, target debris, and high energy neutrons, and 2) operating the chamber at a pulse repetition rate of 5-10 Hz (i.e., re-establishing, the wall protection and chamber conditions needed for beam propagation to the target between pulses). In meeting these challenges, designers have capitalized on the ability to separate the fusion burn physics from the geometry and environment of the fusion chamber. Most recent conceptual designs use gases or flowing liquids inside the chamber. Thin liquid layers of molten salt or metal and low pressure, high-Z gases can protect the first wall from x rays and target debris, while thick liquid layers have the added benefit of protecting structures from fusion neutrons thereby significantly reducing the radiation damage and activation. The use of thick liquid walls is predicted to 1) reduce the cost of electricity by avoiding the cost and down time of changing damaged structures, and 2) reduce the cost of development by avoiding the cost of developing a new, low-activation material. Various schemes have been proposed to assure chamber clearing and renewal of the protective features at the required pulse rate. Representative chamber concepts are described, and key technical feasibility issues are identified for each class of chamber. Experimental activities (past, current, and proposed) to address these issues and technology research and development needs are discussed.
Date: February 27, 1997
Creator: Meier, W. R.; Moir, R. W. & Abdou, M. A.
Partner: UNT Libraries Government Documents Department

Overview of the national spallation neutron source with emphasis on the target station

Description: The technologies that are being utilized to design and build a state-of-the-art neutron spallation source, the National Spallation Neutron Source (NSNS), are discussed. Emphasis is given to the technology issues that present the greatest scientific challenges. The present facility configuration, ongoing analysis and the planned hardware research and development program are also described.
Date: June 1, 1997
Creator: Gabriel, T.A.; Barnes, J.N. & Charlton, L.A.
Partner: UNT Libraries Government Documents Department

Time and motion study for the National Ignition Facility target area

Description: The Department of Energy (DOE) is proposing to construct the National Ignition Facility (NIF) to embark on a program to achieve ignition and modest gain in the laboratory. With annual fusion yields of up to 1200 MJ/year, neutron activation of nearby components is an important issue. Calculations must be performed to ensure that Target Area structures are designed and activities are planned in a way that ensures that such activities can be completed at the required times while meeting all requirements for occupational exposure to radiation. These calculations are referred to as {open_quotes}Lime-motion{close_quotes} studies. In the present work, key Target Area activities are identified and a detailed time-motion study has been completed for the task of debris shield change-out. Results of a preliminary time-motion study for debris shield change-out were used to influence the design. Subsequent analyses have been completed for several point designs of the NIF Final Optics Assembly (FOA). For each FOA point design, a total annual occupational dose equivalent, in person-Sv, has been estimated. Estimates range from 0.19 person-Sv/year (19 person-rem/year) for a composite FOA with a polyethylene plug to 1.38 person-Sv/year (138 person-rem/year) for the baseline FOA design.
Date: June 10, 1996
Creator: Latkowski, J.F. & Tobin, M.T.
Partner: UNT Libraries Government Documents Department

Equation of state measurements of D2 on Nova

Description: In this paper we describe principle Hugoniot measurements of liquid D{sub 2} up to P = 2.1 Mbar. We compressed liquid D{sub 2} with a Nova-laser-driven shock wave launched from an aluminum pusher. The Al/D{sub 2} interface and the shock front in the D{sub 2} are observed with temporally resolved radiography, to determine particle speed U{sub p}, shock speed U{sub s}, and the ratio of final density to initial density {rho}/{rho}{sub 0}. The pressure is calculated. These absolute EOS data reveal a compressibility comparable to the dissociation model.
Date: July 1, 1997
Creator: Collins, G.W.; Da Silva, L.B. & Celliers, P.
Partner: UNT Libraries Government Documents Department

Design of the target area for the National Ignition Facility

Description: The preliminary design of the target area for the National Ignition Facility has been completed. The target area is required to meet a challenging set of engineering system design requirements and user needs. The target area must provide the appropriate conditions before, during, and after each shot. The repeated introduction of large amounts of laser energy into the chamber and subsequent target emissions represent new design challenges for ICF facility design. Prior to each shot, the target area must provide the required target illumination, target chamber vacuum, diagnostics, and optically stable structures. During the shot, the impact of the target emissions on the target chamber, diagnostics, and optical elements is minimized and the workers and public are protected from excessive prompt radiation doses. After the shot, residual radioactivation is managed to allow the required accessibility. Diagnostic data is retrieved, operations and maintenance activities are conducted, and the facility is ready for the next shot. The target area subsystems include the target chamber, target positioner, structural systems, target diagnostics, environmental systems, and the final optics assembly. The engineering design of the major elements of the target area requires a unique combination of precision engineering, structural analysis, opto-mechanical design, random vibration suppression, thermal stability, materials engineering, robotics, and optical cleanliness. The facility has been designed to conduct both x- ray driven targets and to be converted at a later date for direct drive experiments. The NIF has been configured to provide a wide range of experimental environments for the anticipated user groups of the facility. The design status of the major elements of the target area is described.
Date: January 1, 1997
Creator: Foley, R.J.; Karpenko, V.P. & Adams, C.H.
Partner: UNT Libraries Government Documents Department

National Ignition Facility subsystem design requirements target area auxiliary subsystem SSDR 1.8.6

Description: This Subsystem Design Requirement (SSDR) establishes the performance, design, development, and test requirements for the Target Area Auxiliary Subsystems (WBS 1.8.6), which is part of the NIF Target Experimental System (WBS 1.8). This document responds directly to the requirements detailed in NIF Target Experimental System SDR 003 document. Key elements of the Target Area Auxiliary Subsystems include: WBS Local Utility Services; WBS Cable Trays; WBS Personnel, Safety, and Occupational Access; WBS Assembly, Installation, and Maintenance Equipment; WBS Target Chamber Service System; WBS Target Bay Service Systems.
Date: October 20, 1996
Creator: Reitz, T.
Partner: UNT Libraries Government Documents Department

National Ignition Facility for Inertial Confinement Fusion

Description: The National Ignition Facility for inertial confinement fusion will contain a 1.8 MJ, 500 TW frequency-tripled neodymium glass laser system that will be used to explore fusion ignition and other problems in the physics of high temperature and density. We describe the facility briefly. The NIF is scheduled to be completed in 2003.
Date: October 8, 1997
Creator: Paisner, J.A. & Murray, J.R.
Partner: UNT Libraries Government Documents Department

Chamber and target technology development for inertial fusion energy

Description: Fusion chambers and high pulse-rate target systems for inertial fusion energy (IFE) must: regenerate chamber conditions suitable for target injection, laser propagation, and ignition at rates of 5 to 10 Hz; extract fusion energy at temperatures high enough for efficient conversion to electricity; breed tritium and fuel targets with minimum tritium inventory; manufacture targets at low cost; inject those targets with sufficient accuracy for high energy gain; assure adequate lifetime of the chamber and beam interface (final optics); minimize radioactive waste levels and annual volumes; and minimize radiation releases under normal operating and accident conditions. The primary goal of the US IFE program over the next four years (Phase I) is to develop the basis for a Proof-of-Performance-level driver and target chamber called the Integrated Research Experiment (IRE). The IRE will explore beam transport and focusing through prototypical chamber environment and will intercept surrogate targets at high pulse rep-rate. The IRE will not have enough driver energy to ignite targets, and it will be a non-nuclear facility. IRE options are being developed for both heavy ion and laser driven IFE. Fig. 1 shows that Phase I is prerequisite to an IRE, and the IRE plus NIF (Phase II) is prerequisite to a high-pulse rate. Engineering Test Facility and DEMO for IFE, leading to an attractive fusion power plant. This report deals with the Phase-I R&D needs for the chamber, driver/chamber interface (i.e., magnets for accelerators and optics for lasers), target fabrication, and target injection; it is meant to be part of a more comprehensive IFE development plan which will include driver technology and target design R&D. Because of limited R&D funds, especially in Phase I, it is not possible to address the critical issues for all possible chamber and target technology options for heavy ion or laser fusion. On the ...
Date: April 7, 1999
Creator: Abdou, M; Besenbruch, G; Duke, J; Forman, L; Goodin, D; Gulec, K et al.
Partner: UNT Libraries Government Documents Department

Safety and environmental advantages of using tritium-lean targets for inertial fusion

Description: While traditional inertial fusion energy target designs typically use equimolar portions of deuterium and tritium and have areal densities ({rho}r) of {approx} 3 g/cm{sup 2}, significant safety and environmental (S and E) advantages may be obtained through the use of high-density ({rho}r {approx} 10 g/cm{sup 2}) targets with tritium components as low as 0.5%. Such targets would absorb much of the neutron energy within the target and could be self-sufficient from a tritium breeding point of view. Tritium self-sufficiency within the target would free target chamber designers from the need to use lithium-bearing blanket materials, while low inventories within each target would translate into low inventories in target fabrication facilities. Absorption of much of the neutron energy within the target, the extremely low tritium inventories, and the greatly moderated neutron spectrum, make ''tritium-lean'' targets appear quite attractive from an S and E perspective.
Date: August 9, 1999
Creator: Arzeni, S; Latkowski, J F; Logan, B G; Meier, W R; Moir, R W; Perkins, L J et al.
Partner: UNT Libraries Government Documents Department

Unconverted Light Management of the NIF-Wedged Lens Configuration

Description: This document provides information on the distribution of unconverted light in the National Ignition Facility (NIF) target chamber with the wedged final focus lens that has been adopted by the NIF project. It includes a comparison of the wedged lens configuration with the color separation grating (CSG). There are significant benefits to the wedged lens design as it greatly simplifies experiment design.
Date: March 31, 2000
Creator: Kalantar, D.
Partner: UNT Libraries Government Documents Department

A rotating target wheel system for gammasphere.

Description: A description is given for a low-mass, rotating target wheel to be used within the Gammasphere target chamber. This system was developed for experiments employing high beam currents in order to extend lifetimes of targets using low-melting point target material. The design is based on a previously successful implementation of rotating target wheels for the Argonne Positron Experiment (APEX) as well as the Fragment Mass Analyser (FMA) at ATLAS (Argonne Tandem Linac Accelerator System). A brief history of these rotating target wheel systems is given as well as a discussion on target preparation and performance.
Date: January 4, 1999
Creator: Greene, J. P.
Partner: UNT Libraries Government Documents Department

Imaging VISAR diagnostic for the National Ignition Facility (NIF)

Description: The National Ignition Facility (NIF) requires diagnostics to analyze high-energy density physics experiments. A VISAR (Velocity Interferometry System for Any Reflector) diagnostic has been designed to measure shock velocities, shock breakout times, and shock emission of targets with sizes from 1 to 5 mm. An 8-inch-diameter fused silica triplet lens collects light at f/3 inside the 30-foot-diameter vacuum chamber. The optical relay sends the image out an equatorial port, through a 2-inch-thick vacuum window, and into two interferometers. A 60-kW VISAR probe laser operates at 659.5 nm with variable pulse width. Special coatings on the mirrors and cutoff filters are used to reject the NIF drive laser wavelengths and to pass a band of wavelengths for VISAR, passive shock breakout light, or thermal imaging light (bypassing the interferometers). The first triplet can be no closer than 500 mm from the target chamber center and is protected from debris by a blast window that is replaced after every event. The front end of the optical relay can be temporarily removed from the equatorial port, allowing other experimenters to use that port. A unique resolution pattern has been designed to validate the VISAR diagnostic before each use. All optical lenses are on kinematic mounts so that the pointing accuracy of the optical axis can be checked. Seven CCD cameras monitor the diagnostic alignment.
Date: August 30, 2004
Creator: Malone, R M; Bower, J R; Bradley, D K; Capelle, G A; Celeste, J R; Celliers, P M et al.
Partner: UNT Libraries Government Documents Department

Final optics damage inspection (FODI) for the National Ignition Facility

Description: The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory (LLNL) will routinely fire high energy shots (approaching 10 kJ per beamline) through the final optics, located on the target chamber. After a high fluence shot, exceeding 4J/cm2 at 351 nm wavelength, the final optics will be inspected for laser-induced damage. The FODI (Final Optics Damage Inspection) system has been developed for this purpose, with requirements to detect laser-induced damage initiation and to track and size it's the growth to the point at which the optic is removed and the site mitigated. The FODI system is the 'corner stone' of the NIF optic recycle strategy. We will describe the FODI system and discuss the challenges to make optics inspection a routine part of NIF operations.
Date: October 23, 2007
Creator: Conder, A; Alger, T; Azevedo, S; Chang, J; Glenn, S; Kegelmeyer, L et al.
Partner: UNT Libraries Government Documents Department

Timing shifts due to NIF beam repointing

Description: Repointing a NIF beam to hit a target position off target chamber center (TCC) will introduce a timing shift due to changes in the light pathlength. This shift could be important for target experiment requirements even for targets placed at TCC, since beam timing test shots will place beams up to 15 mm off TCC in order to spatially separate them on foil targets. In particular, timing errors due to beam repointing need to be considered against the 30 ps RMS timing requirement. Since the repointing process will keep the beam passing through a fixed point in the final optics assembly (the conversion crystal) by tip/tilt adjustments of two turning mirrors (LM5 and LM7), the problem naturally divides into two parts: Timing offsets past the conversion crystal due to target positioning changes, and timing offsets behind the fixed point on the conversion crystal due to turning mirror adjustments. Timing offsets past the conversion crystal can be significant, but are trivial to calculate exactly; however, an exact calculation of timing offsets behind the fixed point on the conversion crystal would require a three-dimensional optomechanical raytrace model to be developed for every beamline, and this would be difficult and expensive. In this memo, I estimate the magnitude of timing offsets due to pathlength changes behind the conversion crystal by analysis of a worst-case model. I conclude that these timing offsets are insignificant compared with the current allocation in the 30 ps RMS timing requirement, and that more detailed raytrace modeling of individual beams is not necessary.
Date: August 15, 2007
Creator: Koch, J
Partner: UNT Libraries Government Documents Department

Bambino: a segmented silicon detector system for TIGRESS

Description: Bambino is a charge-particle detector system with sufficient energy and position resolutions for the differentiation between projectile-like and target-like particles and for the needed Doppler-shift corrections to the detected {gamma} rays in TIGRESS. It consists of two annular silicon detectors having an active inner diameter of 22 mm and outer diameter of 70 mm and a thickness about 150 {micro}m. They are placed 3.0 cm from the target and provide solid-angle coverage of 1.15{pi} sr. Each has 24 sectors in {theta} for the angle coverage between 20.1{sup o} and 49.4{sup o} and between 130.6{sup o} to 159.9{sup o} and has 16 sectors in {phi} for 2{pi} coverage. Three of those detectors and the matching preamplifiers, cables etc were ordered and received in 2005 at a cost about $50k funded by DOE/OS. The system was undergoing various tests at both LLNL and TRIUMF in the second quarter of 2006 and was successfully integrated into TIGRESS for the commission run in July/August 2006. A side-accessible spherical target chamber, used in the commission run, was designed and built in Rochester in the second quarter of 2006 to accommodate this detector system at a cost about $28k funded by NSF and AFOSR.
Date: August 17, 2006
Creator: Wu, C Y; Becker, J A & Cline, D
Partner: UNT Libraries Government Documents Department

NIF laser bundle review. Final report

Description: We performed additional bundle review effort subsequent to the completion of the preliminary report and are revising our original recommendations. We now recommend that the NIF baseline laser bundle size be changed to the 4x2 bundle configuration. There are several 4x2 bundle configurations that could be constructed at a cost similar to that of the baseline 4x12 (from $11M more to about $11M less than the baseline; unescalated, no contingency) and provide significant system improvements. We recommend that the building cost estimates (particularly for the in-line building options) be verified by an architect/engineer (A/E) firm knowledgeable about building design. If our cost estimates of the in-line building are accurate and therefore result in a change from the baseline U-shaped building layout, the acceptability of the in-line configuration must be reviewed from an operations viewpoint. We recommend that installation, operation, and maintenance of all laser components be reviewed to better determine the necessity of aisles, which add to the building cost significantly. The need for beam expansion must also be determined since it affects the type of bundle packing that can be used and increases the minimum laser bay width. The U-turn laser architecture (if proven viable) offers a reduction in building costs since this laser design is shorter than the baseline switched design and requires a shorter laser bay.
Date: September 15, 1995
Creator: Tietbohl, G.L.; Larson, D.W. & Erlandson, A.C.
Partner: UNT Libraries Government Documents Department

Overview of the NSNS target station

Description: The technologies that are being utilized to design and build a state-of-the-art neutron spallation source, the National Spallation Neutron Source (NSNS), are discussed. Emphasis is given to the technology issues that present the greatest scientific challenges. The present facility configuration, ongoing analysis and the planned hardware research and development program are also described.
Date: April 1, 1997
Creator: Gabriel, T.A.; Barnes, J.M. & Charlton, L. A.
Partner: UNT Libraries Government Documents Department

The Advanced Photon Source (APS) linear accelerator as a source of slow positrons

Description: The Advanced Photon Source linear accelerator (linac) system consists of a 200-MeV, 2856-MHz S-band electron linac, a 2-radiation-length-thick tungsten target for positron production, and a 450-MeV positron linac. The linac is briefly described, and some possibilities for its use as a slow positron source are discussed.
Date: September 1, 1996
Creator: White, M.M. & Lessner, E.S.
Partner: UNT Libraries Government Documents Department

APT target/blanket design and thermal hydraulics

Description: The Accelerator Production of Tritium (APT) Target/Blanket (T/B) system is comprised of an assembly of tritium producing modules supported by control, heat removal, shielding and retargeting systems. The T/B assembly produces tritium using a high-energy proton beam, a tungsten/lead spallation neutron source and {sup 3}He gas as the tritium producing feedstock. For the nominal production mode, protons are accelerated to an energy of 1030 MeV at a current of 100 mA and are directed onto the T/B assembly. The protons are expanded using a raster/expansion system to illuminate a 0.19m by 1.9m beam spot on the front face of a centrally located tungsten neutron source. A surrounding lead blanket produces additional neutrons from scattered high-energy particles. The tungsten neutron source consists of nested, Inconel-718 clad tungsten cylinders assembled in horizontal Inconel-718 tubes. Each tube contains up to 6 cylinders with annular flow channel gaps of 0.102 cm. These horizontal tubes are manifolded into larger diameter vertical inlet and outlet pipes, which provide coolant. The horizontal and vertical tubes make up a structure similar to that of rungs on a ladder. The entire tungsten neutron source consists of 11 such ladders separated into two modules, one containing five ladders and the other six. Ladders are separated by a 0.3 m void region to increase nucleon leakage. The peak thermal-hydraulic conditions in the tungsten neutron source occur in the second ladder from the front. Because tungsten neutron source design has a significant number of parallel flow channels, the limiting thermal-hydraulic parameter is the onset of significant void (OSV) rather than critical heat flux (CHF). A blanket region surrounds the tungsten neutron source. The lateral blanket region is approximately 120 cm thick and 400 cm high. Blanket material consists of lead, {sup 3}He gas, aluminum, and light-water coolant. The blanket region is subdivided ...
Date: April 1, 1999
Creator: Cappiello, M.; Pitcher, E. & Pasamehmetoglu, K.
Partner: UNT Libraries Government Documents Department

IFMIF - International Fusion Materials Irradiation Facility Conceptual Design Activity/Interim Report

Description: Environmental acceptability, safety, and economic viability win ultimately be the keys to the widespread introduction of fusion power. This will entail the development of radiation- resistant and low- activation materials. These low-activation materials must also survive exposure to damage from neutrons having an energy spectrum peaked near 14 MeV with annual radiation doses in the range of 20 displacements per atom (dpa). Testing of candidate materials, therefore, requires a high-flux source of high energy neutrons. The problem is that there is currently no high-flux source of neutrons in the energy range above a few MeV. The goal, is therefore, to provide an irradiation facility for use by fusion material scientists in the search for low-activation and damage-resistant materials. An accellerator-based neutron source has been established through a number of international studies and workshops` as an essential step for materials development and testing. The mission of the International Fusion Materials Irradiation Facility (IFMIF) is to provide an accelerator-based, deuterium-lithium (D-Li) neutron source to produce high energy neutrons at sufficient intensity and irradiation volume to test samples of candidate materials up to about a full lifetime of anticipated use in fusion energy reactors. would also provide calibration and validation of data from fission reactor and other accelerator-based irradiation tests. It would generate material- specific activation and radiological properties data, and support the analysis of materials for use in safety, maintenance, recycling, decommissioning, and waste disposal systems.
Date: December 1, 1995
Creator: Rennich, M.J.
Partner: UNT Libraries Government Documents Department

Proceedings of the international workshop on spallation materials technology

Description: This document contains papers which were presented at the International Workshop on Spallation Materials Technology. Topics included: overviews and thermal response; operational experience; materials experience; target station and component design; particle transport and damage calculations; neutron sources; and compatibility.
Date: October 1, 1996
Creator: Mansur, L.K. & Ullmaier, H.
Partner: UNT Libraries Government Documents Department

Split-target neutronics and the MLNSC spallation target system

Description: The Manuel Lujan, Jr., Neutron Scattering Center (MLNSC) at the Los Alamos National Laboratory is one of four operating Short-Pulse Spallation Sources worldwide. The MLNSC target system (composed of targets, moderators, and reflectors) was first installed in 1985. The target system employs a split tungsten spallation target with a void space in between (the flux-trap gap); this target system will be upgraded in 1998. The ability to efficiently split a spallation target allowed us to introduce the concept of flux-trap moderators and ultimately the notion of backscattering and upstream moderators. The upgraded MLNSC target system will employ both flux-trap and upstream/backscattering moderators to simultaneously service 16 neutron flight paths with high-intensity neutron beams for materials science research.
Date: December 31, 1996
Creator: Russell, G.J.; Ferguson, P.D.; Pitcher, E.J. & Court, J.D.
Partner: UNT Libraries Government Documents Department