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Performance characteristics of the Lysholm engine

Description: The performance of a 5 in. diameter rotor Lysholm engine prototype running on simulated geothermal flows from 16 to 100% quality is described. Staging was performed with conventional Westinghouse 25 kW steam turbines demonstrating that such a process is feasible. Maximum efficiency and power noted were 37.2% and 26.3 kW respectively, but inhibiting factors were discovered which, upon correction, should allow efficiencies around 50% and powers up to 35 kW. Larger engines with minor modifications should get better efficiencies. Data was taken for inlet pressures of 75 to 120 psia and speeds of 3000 to 9000 rpm's. Further testing under similar conditions is planned.
Date: January 1, 1980
Creator: Berger, R.E.
Partner: UNT Libraries Government Documents Department

Saturation of the parametric decay instability near the lower hybrid frequency

Description: The nonlinear evolution and saturation of parametrically excited lower hybrid waves are studied numerically by solving the corresponding weak turbulence wave kinetic equation. The saturation level and the effective collision frequency $nu$/sub f/ are obtained as functions of pump power. (auth)
Date: October 1, 1975
Creator: Chen, L. & Berger, R.L.
Partner: UNT Libraries Government Documents Department

An assessment of potential risk resulting from a maximum credible accident scenario at the proposed explosive waste storage facility (EWSF)

Description: Lawrence Livermore National Laboratory (LLNL) proposes to build, permit, and operate a storage facility for explosive wastes at LLNL`s Explosive Test Site, Site 300. The facility would consist of four existing magazines, four new magazettes (small concrete vaults), and a new prefabricated metal building. Ash from on-site treatment of explosive waste would also be stored in the prefabricated metal building prior to sampling analysis, and shipment. The magazettes would be installed at each magazine-and would provide segregated storage for explosive waste types including detonators, actuators, and other initiating devices. The proposed facility would be used to store explosive wastes generated by the Hydrotest and Explosive Development Programs at LLNL prior to treatment on-site or shipment to permitted, commercial, off-site treatment facilities. Explosive wastes to be stored in the proposed facility represent a full spectrum of Department of Energy (DOE) and LLNL explosive wastes. This document identifies and evaluates the risk to human health and the environment associated with the operation of the proposed EWSF.
Date: October 1, 1992
Creator: Otsuki, K.; Harrach, R. & Berger, R.
Partner: UNT Libraries Government Documents Department

Excitation of fast waves by slow waves near the lower-hybrid frequency

Description: Resonant and non-resonant decays of short wavelength lower hybrid waves into long wave-length whistler waves and ion acoustic waves are considered. It is shown that the dominant coupling to the ion acoustic mode arises from the magnetic force producing a pressure variation along the magnetic field lines. The growth rate and the threshold condition for this decay instability compare favorably with other decay instabilities near the lower-hybrid frequency. (auth)
Date: February 1, 1976
Creator: Berger, R. L. & Chen, L.
Partner: UNT Libraries Government Documents Department

Laser scattering in large-scale-length plasmas relevant to National Ignition Facility hohlraums

Description: We have used homogeneous plasmas of high density (up to 1.3 X 10{sup 21} electrons per cm{sup 3}) and temperature ({approximately} 3 keV) with large density scale lengths ({approximately}2 mm) to approximate conditions within National Ignition Facility (NIF) hohlraums. Within these plasmas we have studied the dependence of stimulated Raman (SRS) and Brillouin (SBS) scattering on beam smoothing and plasma conditions at the relevant laser intensity (3{omega}, 2 X 10{sup 15}Wcm{sup 2}). Both SBS and SRS are reduced by the use of smoothing by spectral dispersion (SSD).
Date: October 1, 1996
Creator: MacGowan, B.J.; Berger, R.L. & Afeyan, B.B.
Partner: UNT Libraries Government Documents Department

Production of a pellet fuel from Illinois coal mines. Quarterly report, 1 December 1994--28 February 1995

Description: The goal of this research is to produce a pellet fuel from low-sulfur Illinois coal fines which could burn with emissions of less than 1.8 lbs SO{sub 2}/10{sup 6} Btu in stoker-fired boilers. The significance of 1.8 lbs SO{sub 2}/10{sup 6} Btu is that in the Chicago (9 counties) and St. Louis (2 counties) metropolitan areas, industrial users of coal currently must comply with this level of emissions. Stokers are an attractive market for pellets because pellets are well-suited for this application and because western coal is not a competitor in the stoker market. Compliance stoker fuels come from locations such as Kentucky and West Virginia and the price for fuels from these locations is high relative to the current price of Illinois coal. This market offers the most attractive near-term economic environment for commercialization of pelletization technology. For this effort, we will be investigating the use of fines from two Illinois mines which currently mine relatively low-sulfur reserves and that discard their fines fraction (minus 100 mesh). The research will involve investigation of multiple unit operations including column flotation, filtration and pellet production. The end result of the effort will allow for an evaluation of the commercial viability of the approach.
Date: December 31, 1995
Creator: Rapp, D.; Lytle, J.; Berger, R. & Ho, Ken
Partner: UNT Libraries Government Documents Department

Stimulated brillouin backscatter of a short-pulse laser

Description: Stimulated Brillouin backscattering (SBBS) from a short-pulse laser, where the pulse length is short compared to the plasma length, is found to be qualitatively different than in the long pulse regime, where the pulse length is long compared to the plasma length. We find that after an initial transient of order the laser pulse length transit time, the instability reaches a steady state in the variables x{prime} = x {minus} V{sub g}t, t{prime} = t, where V{sub g} is the pulse group velocity. In contrast, SBBS in a long pulse can be absolutely unstable and grows indefinitely, or until nonlinearities intervene. We find that the motion of the laser pulse induces Doppler related effects that substantially modify the backscattered spectrum at higher intensities, where the instability is strongly coupled (i.e. , has a growth rate large compared to the ion acoustic frequency).
Date: November 3, 1994
Creator: Hinkel, D.E.; Williams, E.A. & Berger, R.L.
Partner: UNT Libraries Government Documents Department

The study of parametric instabilities in NIF-scale plasmas on Nova

Description: At the same time we experimentally reproduced the plasma conditions expected within the NIF using plasmas produced by the Nova laser. The plasmas were created by irradiating a thin walled gas balloon or a sealed hohlraum containing of order one atmosphere of a low-Z gas (e.g. C{sub 5}H{sub 12}, C{sub 5}D{sub 12} or CO{sub 2}). When the gas is ionized and heated the resultant plasmas are homogeneous, and of high density ({approximately}10{sup 21} electron/cm{sup 3}) and temperature ({approximately}3 keV) with large scale density scale lengths ({approximately}2 mm). Nine of the Nova beams were used to produce the plasma, the tenth beam was configured as an interaction beam that was sent through the performed plasma after a delay of order 500 psec. The SRS and SBS scattered from the plasma, together with the effects of the plasma on the transmitted beam, were studied as a function of the interaction beam intensity, beam smoothing and plasma constituents. The interaction beam was smoothed by using radon phase plates (RPPs), and 4 different colors within the f/8 beam to mimic the NIF laser architecture. The 4-color set-up divided the f/8 beam in to 4 separate quadrants each of which had its wavelength shifted relative to the other quadrants. The wavelength separation of the colors was approximately 1.4{Angstrom} at 3{omega}. Since each beam quadrant could have its frequency conversion crystals individually tuned for its wavelength, the 4-color scheme approximated ``bandwidth`` on the interaction beam without losing 3{omega} conversion efficiency. We have also studied the use of a laser bandwidth of approximately 0.7{Angstrom} and smoothing by Spectral Dispersion (SSD) with all of the quadrants set at the same color, to further reduce the reflected SBS. These studies were performed with both f/4.3 and f/8 interaction beam focusing.
Date: September 26, 1994
Creator: MacGowan, B.J.; Back, C.A. & Berger, R.L.
Partner: UNT Libraries Government Documents Department

Measurements of large scale-length plasmas produced from gas-filled targets

Description: Apart from their intrinsic interest, plasma physics processes are important because they affect the coupling of the laser energy into laser-irradiated targets. Recently, new gas-filled targets have been developed to create large mm-size plasmas for the study of stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS). We present x-ray images and x-ray spectra to characterize these targets, which show that the plasmas are homogeneous, have electron densities of {approximately}10{sup 21} cm{sup {minus}3}, and attain electron temperatures of {approximately}3 keV. We also present SBS measurements to demonstrate how systematic studies of physical phenomena can be performed using these targets.
Date: June 30, 1995
Creator: Back, C.A.; Berger, R.L. & Estabrook, K.
Partner: UNT Libraries Government Documents Department

The Frequency and Damping of Ion Acoustic Waves in Collisional and Collisionless Two-species Plasma

Description: The dispersion properties of ion acoustic waves (IAW) are sensitive to the strength of ion-ion collisions in multi-species plasma in which the different species usually have differing charge-to-mass ratios. The modification of the frequency and damping of the fast and slow acoustic modes in a plasma composed of light (low Z) and heavy (high Z) ions is considered. In the fluid limit where the light ion scattering mean free path, {lambda}{sub th} is smaller than the acoustic wavelength, {lambda} = 2{pi}/k, the interspecies friction and heat flow carried by the light ions scattering from the heavy ions causes the damping. In the collisionless limit, k{lambda}{sub th} >> 1, Landau damping by the light ions provides the dissipation. In the intermediate regime when k{lambda}{sub th} {approx} 1, the damping is at least as large as the sum of the collisional and Landau damping.
Date: August 18, 2004
Creator: Berger, R.L. & Valeo, E.J.
Partner: UNT Libraries Government Documents Department

On the Transition from Thermally-driven to Ponderomotively-driven Stimulated Brillouin Scattering and Filamentation of Light in Plasma

Description: The dispersion properties of ion acoustic waves and their nonlinear coupling to light waves through ponderomotive and thermal forces are sensitive to the strength of electron-ion collisions. Here, we consider the growth rate of stimulated Brillouin scattering (SBS) when the driven acoustic wave frequency and wavelength span the range of small to large compared to electron-ion collision frequency and mean free path respectively. We find in all cases the thermal contributions to the SBS growth rate are insignificant if the ion acoustic wave frequency is greater than the electron-ion collision frequency and the wavelength is much shorter than the electron-ion mean free path. On the other hand, the purely growing filamentation instability remains thermally driven for shorter wavelengths than SBS even when the growth rate is larger than the acoustic frequency.
Date: April 4, 2005
Creator: Berger, R. L.; Valeo, E. J. & Brunner, S.
Partner: UNT Libraries Government Documents Department

Gas-filled targets for large scalelength plasma interaction experiments on Nova

Description: Stimulated Brillouin backscatter from large scale length gas-filled targets has been measured on Nova. These targets were designed to approximate conditions in indirect drive ignition target designs in underdense plasma electron density (n{sub e}{approximately}10{sup 21}/cm{sup 3}), temperature (T{sub e}>3 keV), and gradient scale lengths (L{sub n}{approximately} mm, L{sub v}>6 mm) as well as calculated gain for stimulated Brillouin scattering (SBS). The targets used in these experiments were gas-filled balloons with polyimide walls (gasbags) and gas-filled hohlraums. Detailed characterization using x-ray imaging and x-ray and optical spectroscopy verifies that the calculated plasma conditions are achieved. Time-resolved SBS backscatter from these targets is <3% for conditions similar to ignition target designs.
Date: November 1, 1994
Creator: Powers, L.V.; Berger, R.L. & Munro, D.H.
Partner: UNT Libraries Government Documents Department

Carbonation as a binding mechanism for coal/calcium hydroxide pellets. Final technical report, 1 September, 1992--31 August, 1993

Description: This research was an investigation of calcium hydroxide, a sulfur-capturing sorbent, as a binder for coal fines. The reaction of carbon dioxide with calcium hydroxide, referred to as carbonation, was studied as a method for improving pellet quality. Carbonation forms a cementitious matrix of calcium carbonate. Research has demonstrated that calcium hydroxide is a viable binder for coal fines and that a roller-and-die pellet mill is an effective method of pellet formation. From a minus 28 mesh preparation plant fine coal sample, a roller-and-die pellet mill produced strong pellets when 5 and 10% calcium hydroxide was used as a binder. The pellets containing 10% calcium hydroxide strengthened considerably when air cured. This increase in strength was attributed to carbonation via atmospheric carbon dioxide. Pellets containing 10 wt% calcium hydroxide were produced using an extruder but pellets formed in this manner were much weaker than pellets produced with the roller-and-die mill. In tests performed using a laboratory hydraulic press, the effect of particle size and compaction pressure on pellet strength was studied. Particle distributions with mean sizes of 200, 90 and 40 microns were tested. The results indicate that pellet strength increased with decreasing particle size and increasing compaction pressure when calcium hydroxide was used as a binder. Pellets containing 10 wt% calcium hydroxide increased in strength by approximately 40% when air dried for one day. As above, this increase in strength was attributed to carbonation of the calcium hydroxide via atmospheric carbon dioxide.
Date: December 31, 1993
Creator: Rapp, D.; Lytle, J.; Hackley, K.; Dagamac, M.; Berger, R. & Schanche, G.
Partner: UNT Libraries Government Documents Department

Carbonation as a binding mechanism for coal/calcium hydroxide pellets. Technical report, December 1, 1992--February 28, 1993

Description: Pelletization of fine coal with calcium hydroxide, a sulfur capturing sorbent, represents a method to produce a fuel which will burn in compliance with the recently passed Clean Air Act Amendments (CAAA`s). To harden the pellets, the reaction of carbon dioxide with calcium hydroxide, referred to as carbonation, is being studied. Carbonation forms a bonding matrix of calcium carbonate. This is a two-year research program. This report covers the second quarter of the second year. Research is indicating that 5 to 10 wt% calcium hydroxide pellets can be produced via a roller-and-die pellet mill and air cured to achieve sufficient quality for handling and transportation. This quarter, 1/2 inch-diameter pellets containing 10% calcium hydroxide were demonstrated to gradually react with atmospheric carbon dioxide (3 days) while air drying to achieve compressive strengths equivalent to those attained for fully dried pellets which had been carbonated for one-hour with 100% commercial grade carbon dioxide. It was also demonstrated that an organic, adhesive binder, corn starch, can be very effective at producing strong pellets but drying is required before appreciable pellet strength is attained. For pellets containing 2 wt% corn starch, it was determined that less than 50% of the ultimate strength was achieved as the pellets were dried from 20 wt% to 5 wt% moisture. Strength improved considerably as the pellet moisture content was reduced below 5 wt%.
Date: May 1, 1993
Creator: Rapp, D.; Lytle, J.; Hackley, K.; Dagamac, M.; Berger, R. & Schanche, G.
Partner: UNT Libraries Government Documents Department

Predictive three dimensional modeling of Stimulated Brillouin Scattering in ignition-scale experiments

Description: The first three-dimensional (3D) simulations of a high power 0.351 {micro}m laser beam propagating through a high temperature hohlraum plasma are reported. We show that 3D linear kinetic modeling of Stimulated Brillouin scattering reproduces quantitatively the experimental measurements, provided it is coupled to detailed hydrodynamics simulation and a realistic description of the laser beam from its millimeter-size envelop down to the micron scale speckles. These simulations accurately predict the strong reduction of SBS measured when polarization smoothing is used.
Date: November 7, 2007
Creator: Divol, L; Berger, R; Meezan, N; Froula, D H; Dixit, S; Suter, L et al.
Partner: UNT Libraries Government Documents Department

Three dimensional modeling of Laser-Plasma interaction: benchmarking our predictive modeling tools vs. experiments

Description: We have developed a new target platform to study Laser Plasma Interaction in ignition-relevant condition at the Omega laser facility (LLE/Rochester)[1]. By shooting an interaction beam along the axis of a gas-filled hohlraum heated by up to 17 kJ of heater beam energy, we were able to create a millimeter-scale underdense uniform plasma at electron temperatures above 3 keV. Extensive Thomson scattering measurements allowed us to benchmark our hydrodynamic simulations performed with HYDRA[2]. As a result of this effort, we can use with much confidence these simulations as input parameters for our LPI simulation code pF3d[3]. In this paper, we show that by using accurate hydrodynamic profiles and full three-dimensional simulations including a realistic modeling of the laser intensity pattern generated by various smoothing options, whole beam three-dimensional linear kinetic modeling of stimulated Brillouin scattering reproduces quantitatively the experimental measurements(SBS thresholds, reflectivity values and the absence of measurable SRS). This good agreement was made possible by the recent increase in computing power routinely available for such simulations. These simulations accurately predicted the strong reduction of SBS measured when polarization smoothing is used.
Date: November 8, 2007
Creator: Divol, L; Berger, R; Meezan, N; Froula, D H; Dixit, S; Suter, L et al.
Partner: UNT Libraries Government Documents Department

Laser-plasma interaction in ignition relevant plasmas: benchmarking our 3D modelling capabilities versus recent experiments

Description: We have developed a new target platform to study Laser Plasma Interaction in ignition-relevant condition at the Omega laser facility (LLE/Rochester)[1]. By shooting an interaction beam along the axis of a gas-filled hohlraum heated by up to 17 kJ of heater beam energy, we were able to create a millimeter-scale underdense uniform plasma at electron temperatures above 3 keV. Extensive Thomson scattering measurements allowed us to benchmark our hydrodynamic simulations performed with HYDRA [1]. As a result of this effort, we can use with much confidence these simulations as input parameters for our LPI simulation code pF3d [2]. In this paper, we show that by using accurate hydrodynamic profiles and full three-dimensional simulations including a realistic modeling of the laser intensity pattern generated by various smoothing options, fluid LPI theory reproduces the SBS thresholds and absolute reflectivity values and the absence of measurable SRS. This good agreement was made possible by the recent increase in computing power routinely available for such simulations.
Date: September 27, 2007
Creator: Divol, L; Froula, D H; Meezan, N; Berger, R; London, R A; Michel, P et al.
Partner: UNT Libraries Government Documents Department

LLNL NESHAPs project. 1992 annual report

Description: This report summarizes work conducted during FY 1992 for the Environmental Monitoring and Analysis Division of the Environmental Protection Department at Lawrence Livermore National Laboratory (LLNL). This document contains information regarding environmental monitoring of a wide variety of radioisotopes which are emitted to the atmosphere. These radioisotopes include transuranics, biomedical tracers, tritium, mixed fission products, and other radioisotopes used for general research and nuclear weapons research. Information regarding radionuclide air emissions for each of the 56 buildings at LLNL where radionuclides are used or activation products occur is given. Detailed information is included for all point source emissions from 43 LLNL site buildings. In addition, dose equivalents and dose assessment are evaluated. Reported annual releases are based on inventory data and unabated EPA potential release fractions for unmonitored sources, and on actual emission measurements for continuously monitored facilities.
Date: May 1, 1993
Creator: Surano, K. A.; Failor, R. A.; Biermann, A. H.; Berger, R. L. & Harrach, R. J.
Partner: UNT Libraries Government Documents Department

Green (2(omega)) Laser Beam propagation in high-temperature Hohlraum Plasmas

Description: We demonstrate propagation and small backscatter losses of a frequency-doubled (2{omega}) laser beam interacting with inertial confinement fusion hohlraum plasmas. The electron temperature of 3.3 keV, approximately a factor of two higher than achieved in previous experiments with open geometry targets, approaches plasma conditions of high-fusion yield hohlraums. In this new temperature regime, we measure 2{omega} laser beam transmission approaching 80% with simultaneous backscattering losses of less than 10%. These findings suggests that good laser coupling into fusion hohlraums using 2{omega} light is possible.
Date: October 26, 2007
Creator: Niemann, C; Berger, R; Divol, L; Froula, D H; Jones, O S; Kirkwood, R K et al.
Partner: UNT Libraries Government Documents Department