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Search for faint galactic features

Description: Trying to determine the size of galaxies and looking for tails and connections between galaxies can be intriguing. These very faint features are often buried in the film grain noise. Our study is of the NGC 3623, NGC 3627 and NGC 3628 region. The search for these faint features is complicated by film variation, sky background, microdensitometer drift and stars in the neighborhood of the galaxies. These questions are addressed and faint features are found with the use of judicious data stretching and averaging along suspected features.
Date: January 1, 1980
Creator: Matuska, W. & Burkhead, M.S.
Partner: UNT Libraries Government Documents Department

Row charge cratering calculations. [Feasibility studies]

Description: Two-dimensional calculations have been done to determine the feasibility of constructing deep canals with nuclear explosives subject to the limitation in the proposed PNE Treaty. The conditions under which a series of explosives set in a row can be approximated by a cylindrical line source have been determined. Using this result, the possibility of lifting 250 m of overburden with 150-kt charges spaced at 50-m intervals has been investigated. This study shows that for a variety of equations of state for the geological medium, there appears little possibility that such an excavation can be accomplished.
Date: June 1, 1978
Creator: Miller, L.W. & Matuska, W.
Partner: UNT Libraries Government Documents Department

Polynomial solutions of the Schroedinger equation applied to photon cross sections in atoms

Description: Solutions of the Schrodinger equation with a realistic potential are carried out in detail. To check the methods, a few boundbound, bound-free, and free-free cross sections were calculated and values compared with existing calculations and experimental data. These comparisons, along with a listing of the computer code in its bound-free form, are included. (auth)
Date: August 1, 1973
Creator: Merts, A.L. & Matuska, W. Jr.
Partner: UNT Libraries Government Documents Department

Determining the temperature and density distribution from a Z-pinch radiation source

Description: High temperature radiation sources exceeding one hundred eV can be produced via z-pinches using currently available pulsed power. The usual approach to compare the z-pinch simulation and experimental data is to convert the radiation output at the source, whose temperature and density distributions are computed from the 2-D MHD code, into simulated data such as a spectrometer reading. This conversion process involves a radiation transfer calculation through the axially symmetric source, assuming local thermodynamic equilibrium (LTE), and folding the radiation that reaches the detector with the frequency-dependent response function. In this paper the authors propose a different approach by which they can determine the temperature and density distributions of the radiation source directly from the spatially resolved spectral data. This unfolding process is reliable and unambiguous for the ideal case where LTE holds and the source is axially symmetric. In reality, imperfect LTE and axial symmetry will introduce inaccuracies into the unfolded distributions. The authors use a parameter optimization routine to find the temperature and density distributions that best fit the data. They know from their past experience that the radiation source resulting from the implosion of a thin foil does not exhibit good axial symmetry. However, recent experiments carried out at Sandia National Laboratory using multiple wire arrays were very promising to achieve reasonably good symmetry. For these experiments the method will provide a valuable diagnostic tool.
Date: November 1, 1997
Creator: Matuska, W. & Lee, H.
Partner: UNT Libraries Government Documents Department

X-ray source production in foil implosion machines

Description: A number of two-dimensional radiation-magneto-hydrodynamic foil implosion calculations are discussed which explore ways of producing warm x-ray sources ({approximately}60 eV) in a reproducible manner and which would permit close-in access to the source. The discussions include the effects of contoured electrodes on the foil implosion and source output, and of tapering the average mass distribution along the length of the foil. Primarily, source evaluation by jet formation and stagnation against a dense stopping block is treated.
Date: September 1, 1995
Creator: Rich, M. & Matuska, W.
Partner: UNT Libraries Government Documents Department

Measurement and simulation of apertures on Z hohlraums

Description: The authors have performed aperture measurements and simulations for vacuum hohlraums heated by wire array implosions. A low-Z plastic coating is often applied to the aperture to create a high ablation pressure which retards the expansion of the gold hohlraum wall. However, this interface is unstable and may be subjects to the development of highly nonlinear perturbations (jets) as a result of shocks converging near the edge of the aperture. These experiments have been simulated using Lagrangian and Eulerian radiation hydrodynamics codes.
Date: December 1, 1998
Creator: Chrien, R.E.; Matuska, W. Jr. & Swenson, F.J.
Partner: UNT Libraries Government Documents Department

Comparing calculated and measured x-ray images

Description: In recent years 2-dimensional radiation-magneto-hydrodynamic (RMHD) calculations have done quite well in matching some important observed parameters of a z-pinch implosion. As the authors gain experience, they field more complex experiments to compare with calculations. Here they discuss both time dependent and time integrated x-ray imaging on Pegasus. Images, using similar filters, are calculated and compared with the data. They also apply some image enhancement to the data.
Date: September 1, 1995
Creator: Matuska, W.; Benage, J.; Idzorek, G.; Lebeda, C. & Peterson, D.
Partner: UNT Libraries Government Documents Department

Source to detector spectrum transformation and its inverse for the Pegasus Z-pinch

Description: We have developed a ray-tracing code which enables us to calculate the spectrum from a 2-D source simulation and compare directly with experimental data. This code also allows us to study the various spectral components which can potentially be used to determine the source from measured data.
Date: January 1, 1993
Creator: Matuska, W.; Lee, Huan; Hockaday, R. & Peterson, D.
Partner: UNT Libraries Government Documents Department

Source to detector spectrum transformation and its inverse for the Pegasus Z-pinch

Description: We have developed a ray-tracing code which enables us to calculate the spectrum from a 2-D source simulation and compare directly with experimental data. This code also allows us to study the various spectral components which can potentially be used to determine the source from measured data.
Date: May 1, 1993
Creator: Matuska, W.; Lee, Huan; Hockaday, R. & Peterson, D.
Partner: UNT Libraries Government Documents Department

Two-dimensional simulations of foil implosion experiments on the Los Alamos capacitor bank

Description: A number of z-pinch experiments have been conducted at Los Alamos on the Pegasus capacitor bank in which 2-cm high, 5-cm radius, thin foil loads were imploded with currents in excess of 3 MA. Two-dimensional radiation magnetohydrodynamic (RMHD) simulations of these implosions have been performed to model the implosion dynamics and subsequent generation of an x-ray pulse. Comparison of the simulation instability development with visible light framing camera photographs show good agreement and illustrate the instability evolution from short to long wavelengths and a final disruption of the imploding plasma shell. The calculations also show good agreement with experimental timing and measured current and voltage waveforms, and also reproduce features characteristic of the x-ray output. These include a broad pulsewidth, and thepresence of multiple peaks and small time scale structures, features which cannot be reproduced by one-dimensional models. X-ray spectra obtained from the calculated pinch also reproduce qualitative features inthe measured spectra.
Date: January 1, 1993
Creator: Peterson, D.L.; Bowers, R.L.; Brownell, J.H.; Greene, A.E.; Lee, H. & Matuska, W.
Partner: UNT Libraries Government Documents Department

Two-dimensional simulations of foil implosion experiments on the Los Alamos capacitor bank

Description: A number of z-pinch experiments have been conducted at Los Alamos on the Pegasus capacitor bank in which 2-cm high, 5-cm radius, thin foil loads were imploded with currents in excess of 3 MA. Two-dimensional radiation magnetohydrodynamic (RMHD) simulations of these implosions have been performed to model the implosion dynamics and subsequent generation of an x-ray pulse. Comparison of the simulation instability development with visible light framing camera photographs show good agreement and illustrate the instability evolution from short to long wavelengths and a final disruption of the imploding plasma shell. The calculations also show good agreement with experimental timing and measured current and voltage waveforms, and also reproduce features characteristic of the x-ray output. These include a broad pulsewidth, and thepresence of multiple peaks and small time scale structures, features which cannot be reproduced by one-dimensional models. X-ray spectra obtained from the calculated pinch also reproduce qualitative features inthe measured spectra.
Date: May 1, 1993
Creator: Peterson, D. L.; Bowers, R. L.; Brownell, J. H.; Greene, A. E.; Lee, H. & Matuska, W.
Partner: UNT Libraries Government Documents Department

Preliminary investigation of changes in x-ray multilayer optics subjected to high radiation flux

Description: A variety of metal multilayers was exposed to high x-ray flux using Sandia National Laboratories' PROTO II machine in the gas puff mode. Fluxes incident on the multilayers above 700 MW/cm/sup 2/ in total radiation, in nominal 20 ns pulses, were realized. The neon hydrogen- and helium-like resonance lines were used to probe the x-ray reflectivity properties of the multilayers as they underwent change of state during the heating pulse. A fluorescer-fiber optic-streak camera system was used to monitor the changes in x-ray reflectivity as a function of time and irradiance. Preliminary results are presented for a W/C multilayer. Work in progress to model the experiment is discussed. 13 refs., 4 figs.
Date: January 1, 1985
Creator: Hockaday, M.P.; Blake, R.L.; Grosso, J.S.; Selph, M.M.; Klein, M.M.; Matuska, W. Jr. et al.
Partner: UNT Libraries Government Documents Department

Exploring Ways to Improve Predictive Capability of Z-Pinch Calculations

Description: For some time 2-dimensional RMHD (radiation magneto-hydrodynamic) calculations of radiating z-pinches have been made to agree with integral data (current wave form, yield and power). For these calculations, the agreement with detailed data, such as time-resolved x-ray images, is generally not as good. Correctly modeling the physics of z-pinches, including detailed data, is needed to have true predictive capability. To address this problem, the authors first determine which integral data are most sensitive to the details in the models. With this information, they investigate aspects of the pinch, to which the data is sensitive, using non-standard techniques. For example, the pinch is calculated in (x,y)-geometry to investigate how a non-symmetric implosion affects the simulated data.
Date: October 19, 1998
Creator: Matuska, W.; Aubrey, J.; Bowers, R.; Lee, H.; Peterson, D.; Deeney, C. et al.
Partner: UNT Libraries Government Documents Department

Comparison and analysis of 2-D simulation results with two implosion radiation experiments on the Los Alamos Pegasus I and Pegasus II capacitor banks

Description: Two experiments, PegI-41, conducted on the Los Alamos Pegasus I capacitor bank, and PegII-25, on the Pegasus II bank, consisted of the implosions of 13 mg (nominal), 5 cm radius, 2 cm high thin cylindrical aluminum foils resulting in soft x-ray radiation pulses from the plasma thermalization on axis. The implosions were conducted in direct-drive (no intermediate switching) mode with peak currents of about 4 MA and 5 MA respectively, and implosion times of about 2.5 {micro}s and 2.0 {micro}s. A radiation yield of about 250 kJ was measured for PegII-25. The purpose of these experiments was to examine the physics of the implosion and relate this physics to the production of the radiation pulse and to provide detailed experimental data which could be compared with 2-D radiation-magnetohydrodynamic (RMHD) simulations. Included in the experimental diagnostic suites were faraday rotation and dB/dt current measurements, a visible framing camera, an x-ray stripline camera, time-dependent spectroscopy, bolometers and XRD`S. A comparison of the results from these experiments shows agreement with 2-D simulation results in the instability development, current, and radiation pulse data, including the pulsewidth, shape, peak power and total radiation yield as measured by bolometry. Instabilities dominate the behavior of the implosion and largely determine the properties of the resulting radiation pulse. The 2-D simulations can be seen to be an important tool in understanding the implosion physics.
Date: September 1, 1995
Creator: Peterson, D.L.; Bowers, R.L.; Lebeda, C.F.; Matuska, W.; Benage, J.; Idzorek, G. et al.
Partner: UNT Libraries Government Documents Department

Dynamics of a Z Pinch X Ray Source for Heating ICF Relevant Hohlraums to 120-160eV

Description: A z-pinch radiation source has been developed that generates 60 {+-} 20 KJ of x-rays with a peak power of 13 {+-} 4 TW through a 4-mm diameter axial aperture on the Z facility. The source has heated NIF (National Ignition Facility)-scale (6-mm diameter by 7-mm high) hohlraums to 122 {+-} 6 eV and reduced-scale (4-mm diameter by 4-mm high) hohlraums to 155 {+-} 8 eV -- providing environments suitable for indirect-drive ICF (Inertial Confinement Fusion) studies. Eulerian-RMHC (radiation-hydrodynamics code) simulations that take into account the development of the Rayleigh-Taylor instability in the r-z plane provide integrated calculations of the implosion, x-ray generation, and hohlraum heating, as well as estimates of wall motion and plasma fill within the hohlraums. Lagrangian-RMHC simulations suggest that the addition of a 6 mg/cm{sup 3} CH{sub 2} fill in the reduced-scale hohlraum decreases hohlraum inner-wall velocity by {approximately}40% with only a 3--5% decrease in peak temperature, in agreement with measurements.
Date: July 10, 2000
Creator: SANFORD,THOMAS W. L.; OLSON,RICHARD E.; MOCK,RAYMOND CECIL; CHANDLER,GORDON A.; LEEPER,RAMON J.; NASH,THOMAS J. et al.
Partner: UNT Libraries Government Documents Department

Experimental results and modeling of a dynamic hohlraum on SATURN

Description: Experiments were performed at SATURN, a high current z-pinch, to explore the feasibility of creating a hohlraum by imploding a tungsten wire array onto a low-density foam. Emission measurements in the 200--280 eV energy band were consistent with a 110--135 eV Planckian before the target shock heated, or stagnated, on-axis. Peak pinch radiation temperatures of nominally 160 eV were obtained. Measured early time x-ray emission histories and temperature estimates agree well with modeled performance in the 200--280 eV band using a 2D radiation magneto-hydrodynamics code. However, significant differences are observed in comparisons of the x-ray images and 2D simulations.
Date: June 1, 1998
Creator: Derzon, M.S.; Allshouse, G.O.; Deeney, C.; Leeper, R.J.; Nash, T.J.; Matuska, W. et al.
Partner: UNT Libraries Government Documents Department

Application of 2-D Simulations to Z-Pinch Experiment Design and Analysis

Description: The successful 2-D simulations of z-pinch experiments (reproducing such features as the measured experimental current drive, radiation pulse shape, peak power and total radiated energy) can lead to a better understanding of the underlying physics in z-pinch implosions and to the opportunity to use such simulations in the analysis of experimental data and in the design of new experiments. Such use has been made with LANL simulations of experiments on the Sandia Saturn and Z accelerators. Applications have included ''vacuum'' and ''dynamic'' hohlraum experiments; variations in mass, radius and length; and ''nested'' array configurations. Notable examples include the explanation of the power/length results in reduced length pinches and the prediction of the current best power and pulsewidth nested array experiment. Examples of circumstances where the simulation results do not match the experiments will be given along with a discussion of opportunities for improved simulation results.
Date: October 19, 1998
Creator: Peterson, D.L.; Bowers, R.L.; Matuska, W.; Chandler, G.A.; Deeney, C.; Derzon, M.S. et al.
Partner: UNT Libraries Government Documents Department

Z-Pinch Generated X-Rays in Static-Wall Hohlraum Geometry Demonstrate Potential for Indirect-Drive ICF Studies

Description: Hohlraums of full ignition scale (6-mm diameter by 7-mm length) have been heated by x-rays from a z-pinch target on Z to a variety of temperatures and pulse shapes which can be used to simulate the early phases of the National Ignition Facility (NIF) temperature drive. The pulse shape is varied by changing the on-axis target of the z pinch in a static-wall-hohlraum geometry. A 2-{micro}m-thick walled Cu cylindrical target of 8-mm diameter filled with 10 mg/cm{sup 3} CH, for example, produces foot-pulse conditions of {minus}85 eV for a duration of {approximately} 10 ns, while a solid cylindrical target of 5-mm diameter and 14-mg/cm{sup 3} CH generates first-step-pulse conditions of {approximately} 122 eV for a duration of a few ns. Alternatively, reducing the hohlraum size (to 4-mm diameter by 4-mm length) with the latter target has increased the peak temperature to {approximately} 150 eV, which is characteristic of a second-step-pulse temperature. In general, the temperature T of these x-ray driven hohlraums is in agreement with the Planckian relation (T-(P/A){sup 1/4}). P is the measured x-ray input power and A is the surface area of the hohlraum. Fully-integrated 2-D radiation-hydrodynamic simulations of the z pinch and subsequent hohlraum heating show plasma densities within the useful volume of the hohlraums to be on the order of air or less.
Date: August 25, 1999
Creator: Sandord, T.W.L.; Olson, R.E.; Chandler, G.A.; Hebron, D.E.; Mock, R.C.; Leeper, R.J. et al.
Partner: UNT Libraries Government Documents Department

Characteristics of ICF Relevant Hohlraums Driven by X-Rays from a Z-Pinch

Description: Radiation environments characteristic of those encountered during the low-temperature foot pulse and subsequent higher-temperature early-step pulses (without the foot pulse) required for indirect-drive ICF ignition on the National ignition Facility have been produced in hohlraums driven by x-rays from a z-pinch. These environments provide a platform to better understand the dynamics of full-scale NIF hohlraums, ablator material, and capsules prior to NIF completion. Radiation temperature, plasma fill, and wall motion of these hohlraums are discussed.
Date: November 3, 1999
Creator: BOWERS,R.L.; CHANDLER,GORDON A.; HEBRON,DAVID E.; LEEPER,RAMON J.; MATUSKA,W.; MOCK,RAYMOND CECIL et al.
Partner: UNT Libraries Government Documents Department

Soft X-Ray Measurements of Z-Pinch-Driven Vacuum Hohlraums

Description: This article reports the experimental characterization of a z-pinch driven-vacuum hohlraum. The authors have measured soft x-ray fluxes of 5 x 10{sup 12} W/cm{sup 2} radiating from the walls of hohlraums which are 2.4--2.5 cm in diameter by 1 cm tall. The x-ray source used to drive these hohlraums was a z-pinch consisting of a 300 wire tungsten array driven by a 2 MA, 100 ns current pulse. In this hohlraum geometry, the z-pinch x-ray source can produce energies in excess of 800 kJ and powers in excess of 100 TW to drive these hohlraums. The x-rays released in these hohlraums represent greater than a factor of 25 in energy and more than a factor of three in x-ray power over previous laboratory-driven hohlraums.
Date: July 21, 1999
Creator: Baker, K. L.; Porter, J. L.; Ruggles, L. E.; Chandler, G. A.; Deeney, Chris; Vargas, M. et al.
Partner: UNT Libraries Government Documents Department