Characterization of transient gain x-ray lasers (open access)

Characterization of transient gain x-ray lasers

We have performed numerical simulations of the transient collisional excitation Ni-like Pd 4d {r_arrow} 4p J = 0 {r_arrow} 1 147 {angstrom} laser transition recently observed at Lawrence Livermore National Laboratory (LLNL). The high gain {approximately}35 cm results from the experiment are compared with detailed modeling simulations from the 1-D RADEX code in order to better understand the main physics issues affecting the measured gain and x-ray laser propagation along the plasma column. Simulations indicate that the transient gain lifetime associated with the short pulse pumping and refraction of the x-ray laser beam out of the gain region are the main detrimental effects. Gain lifetimes of {approximately}7 ps(1/e decay) are inferred from the smoothly changing gain experimental observations and are in good agreement with the simulations. Furthermore, the modeling results indicate the presence of a longer-lived but lower gain later in time associated with the transition from transient to quasi-steady state excitation.
Date: February 7, 1999
Creator: Dunn, J; Osterheld, A & Shlyaptsev, V
Object Type: Article
System: The UNT Digital Library
Progress in table-top transient collisional excitation x-ray lasers at LLNL (open access)

Progress in table-top transient collisional excitation x-ray lasers at LLNL

We present progress in experiments for high efficiency Ne-like and Ni-like ion x-ray lasers using the transient collisional excitation scheme. Experimental results have been obtained on the COMET 15 TW table-top laser system at the Lawrence Livermore National Laboratory (LLNL). The plasma formation, ionization and collisional excitation of the x-ray laser have been optimized using two sequential laser pulses of 600 ps and 1 ps duration with an optional pre-pulse. We have observed high gains up to 55 cm{sup {minus}1} in Ne-like and Ni-like ion schemes for various atomic numbers. We report strong output for the 4d - 4p line in lower Z Ni-like ion sequence for Mo to Y, lasing from {approximately}190 {angstrom} to 240 {angstrom}, by pumping with less than 5 J energy on target.
Date: February 7, 1999
Creator: Da Silva, L. B.; Dunn, J.; Li, Y.; Nilsen, J.; Osterheld, A.; Shepherd, R. et al.
Object Type: Article
System: The UNT Digital Library
Modeling of laser produced plasma and z-pinch x-ray lasers (open access)

Modeling of laser produced plasma and z-pinch x-ray lasers

In this work we describe our theoretical activities in two directions of interest. First, we discuss progress in modeling laser produced plasmas mostly related to transient collisional excitation scheme experiments with Ne- and recently with Ni-like ions. Calculations related to the delay between laser pulses, transient gain duration and hybrid laser/capillary approach are described in more detail. Second, the capillary discharge plasma research, extended to wider range of currents and rise-times has been outlined. We have systematically evaluated the major plasma and atomic kinetic properties by comparing near- and far-field X-ray laser output with that for the capillary Argon X-ray laser operating under typical current values. Consistent with the experiment insight was obtained for the 469{angstrom} X-ray laser shadowgraphy experiments with very small kiloamp currents. At higher currents, as much as {approximately}200 kA we evaluated plasma temperature, density and compared x-ray source size and emitted spectra.
Date: February 7, 1999
Creator: Dunn, J.; Frati, M.; Gonzales, J. J.; Kalashnikov, M. P.; Marconi, M. C.; Moreno, C. H. et al.
Object Type: Article
System: The UNT Digital Library
Capabilities and resources for tritium research and development (open access)

Capabilities and resources for tritium research and development

Information and flow diagrams are presented from a presentation on tritium research and development activities at the Mound Laboratory. Topics include metal-hydrogen systems, gas dynamics and cryogenic separations, materials research, and helium diffusion and tritium effluent control.
Date: February 7, 1974
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Poynting vectors and electric field distributions in simple dielectric gratings (open access)

Poynting vectors and electric field distributions in simple dielectric gratings

The authors discuss, with illustrations drawn from the simple example of a dielectric grating under total internal reflection illumination, the use of electric field, energy density and Poynting vector as tools for understanding phenomena associated with dielectric gratings. The electric field has greatest direct observational interest, and exhibits patterns of nodes and antinodes that are both expected and intuitive. The energy density, though not directly linked with photoelectric response, has readily understood global patterns. The Poynting vector has more elaborate structure, involving patterns of curls, but the patterns are sensitive to small changes in illumination angle or groove depth. Plots of Poynting vectors may not be as useful for dielectric structures as they are for metals.
Date: February 7, 1996
Creator: Shore, B. W.; Feit, M. D. & Li, L.
Object Type: Article
System: The UNT Digital Library
Hydride compositions (open access)

Hydride compositions

Disclosed are a composition for use in storing hydrogen and a method for making the composition. The composition comprises a mixture of two or more hydrides, each hydride having a different series of hydrogen sorption isotherms that contribute to the overall isotherms of the mixture. The hydrides are chosen so that the isotherms of the mixture have regions wherein the H equilibrium pressure increases with increasing hydrogen, preferably linearly. The isotherms of the mixture can be adjusted by selecting hydrides with different isotherms and by varying the amounts of the individual hydrides, or both. Preferably, the mixture is made up of hydrides that have isotherms with substantially flat plateaus and in nearly equimolar amounts. The composition is activated by degassing, exposing to H, and then heating below the softening temperature of any of the constituents. When the composition is used to store hydrogen, its hydrogen content can be found simply by measuring P{sub H}{sub 2} and determining H/M from the isothermic function of the composition.
Date: February 7, 1994
Creator: Lee, Myung W.
Object Type: Patent
System: The UNT Digital Library
Investigation of mineral transformations and ash deposition during staged combustion. Quarterly technical progress report, October 1, 1995--December 31, 1995 (open access)

Investigation of mineral transformations and ash deposition during staged combustion. Quarterly technical progress report, October 1, 1995--December 31, 1995

Progress during the ninth quarter of a three-year study of ash formation and deposition was made in several areas. One of the key contributions this quarter was the development of an enhanced method for classification of CCSEM data. This classification algorithm permits grouping and comparison of particles previously labeled as ``unclassifiable.`` A second analytical advancement, also made this quarter, provides more detailed information on the distribution of minerals in the coal and the potential for coalescence. This new multiple analysis technique is also applicable to ash and will permit identification of heterogeneous ash particles. Additional analyses of ash samples were also performed and it was found that the firing of Pittsburgh {number_sign}8 under staged combustion conditions yields an ash with a significantly larger particle size distribution than that obtained under conventional firing conditions, but without a significant change in composition. the size difference was noted previously, but the new classification algorithm allowed a detailed comparison of all composition groups, including unclassifiable particles, in the ashes. A mechanistic explanation for this behavior has been developed and is provided in the report. Finally, a paper documenting the new classification algorithm has been prepared and is scheduled for presentation at the March ACS …
Date: February 7, 1996
Creator: Harb, John N.
Object Type: Report
System: The UNT Digital Library
The Savannah River Site`s groundwater monitoring program: 1990 sampling schedule (open access)

The Savannah River Site`s groundwater monitoring program: 1990 sampling schedule

This schedule provides a final record of the 1990 sampling schedule for the SRS groundwater monitoring program conducted by the Environmental Protection Department/Environmental Section (EPD/EMS). It includes all the wells monitored by EPD/EMS at SRS during 1990 and identifies the constituents sampled, the sampling frequency, and the reasons for sampling. Sampling requests are incorporated into the schedule throughout the year. Drafts of the schedule are produced and revised quarterly.
Date: February 7, 1991
Creator: Rogers, C.D.
Object Type: Report
System: The UNT Digital Library
CM modeling report (open access)

CM modeling report

This report compiles TWRS configuration management pre- implementation assessments, categorizes findings, and highlights programs identified for improvement.
Date: February 7, 1997
Creator: Vann, J.M., Fluor Daniel Hanford
Object Type: Report
System: The UNT Digital Library
Engineering task plan for BX/BY compressor upgrade (open access)

Engineering task plan for BX/BY compressor upgrade

This Engineering Task Plan outlines the remaining work to be completed for the BX/BY Instrument Air upgrade. Initial work efforts were guided by Engineering Work Plan, ``BX-BY Compressor Upgrade`` dated 1-25-93 (see Attachment A) which is provided for information. The overall engineering task is to provide a permanent replacement for the instrument air supply system for the 241-BX/BY Tank Farms. The existing system consists of a 25 horsepower Worthington non-lube compressor and an Oriad air dryer. The existing equipment is dated, requires high maintenance and is located in a contaminated zone making it unusable. The BX/BY instrument air replacement unit will be one of the 100 SCFM generic air stations. This station will be permanently sited with the addition of drawing changes to provide a concrete foundation, air piping to existing lines and electrical power supply tie-ins.
Date: February 7, 1995
Creator: Strand, R.G.
Object Type: Report
System: The UNT Digital Library
Tank 241-AP-108 grab sampling and analysis plan (open access)

Tank 241-AP-108 grab sampling and analysis plan

This Sampling and Analysis Plan (SAP) will identify characterization objectives for sample collection, laboratory analytical evaluation, and reporting requirements for tank 241-AP-108 (AP 108). It is written in accordance with the Tank 241-AP-108 Tank Characterization Plan, the Tank Safety Screening Data Quality Objective, the 242-A Evaporator Liquid Effluent Retention Facility Data Quality Objectives, and the Data Quality Objectives for Tank Farms Waste Compatibility Program.
Date: February 7, 1997
Creator: Baldwin, J.H., Fluor Daniel Hanford
Object Type: Report
System: The UNT Digital Library
1996 Central New Mexico Section [American Chemical Society] annual report (open access)

1996 Central New Mexico Section [American Chemical Society] annual report

The main goal of the Central New Mexico Section this year was to increase attendance at the local meetings. Throughout the course of the year attendance at the meeting more than doubled. This was brought on by several factors: having the meeting spread throughout the section (Albuquerque, Santa Fe, Las Vegas, Socorro, Los Alamos); supplementing the ACS National Tour speakers with interesting local sections speakers; and making full use of the newly formed Public Relations Committee. Activities during 1996 are summarized.
Date: February 7, 1997
Creator: Cournoyer, M.E.
Object Type: Report
System: The UNT Digital Library
B Plant process piping replacement feasibility study (open access)

B Plant process piping replacement feasibility study

Reports on the feasibility of replacing existing embedded process piping with new more corrosion resistant piping between cells and between cells and a hot pipe trench of a Hanford Site style canyon facility. Provides concepts for replacement piping installation, and use of robotics to replace the use of the canyon crane as the primary means of performing/supporting facility modifications (eg, cell lining, pipe replacement, equipment reinstallation) and operational maintenenace.
Date: February 7, 1996
Creator: Howden, G.F.
Object Type: Report
System: The UNT Digital Library
Federal Emergency Management Information System (FEMIS) Bill of Materials (BOM) for FEMIS Version 1.3 (open access)

Federal Emergency Management Information System (FEMIS) Bill of Materials (BOM) for FEMIS Version 1.3

This document describes the Bill of Materials (BOM) for the Federal Emergency Management Information System (FEMIS) for version 1.3. FEMIS runs on a client/server platform consisting of a UNIX system, employed as a data server, and personal computers (PCs) using the Windows NT operating system. Servers and PCs require the operating system, utility software, communications and other internal cards that are also listed in the following sections. FEMIS will support the use of Commercial Off-The-Shelf (COTS) software applications and tools. Several configurations are possible at a Chemical Stockpile Emergency Preparedness Program (CSEPP) site. In this description, a site is understood to be compromised of several installations, including the depot, surrounding Immediate Response Zone (IRZ) and Protective Action Zone (PAZ) counties, and one or more state Emergency Operations Centers (EOCs). In general, the main differences between possible configurations are the number of users at an installation, the location of the UNIX data server(s), and wide area network (WAN) link between installations. The number of PC workstations will vary between installations.
Date: February 7, 1997
Creator: Burford, M. J.; Gerhardstein, L. H.; Johnson, R. L.; Loveall, R. M.; Martin, T. J.; Millard, W. D. et al.
Object Type: Report
System: The UNT Digital Library
Nondestructive computed tomography for pit inspections (open access)

Nondestructive computed tomography for pit inspections

Objective is to develop new approaches to electronically capture digital radiography and computed tomography images at high x-ray energies to satisfy spatial and contrast requirements for inspection of high-density weapons components.
Date: February 7, 1997
Creator: Martz, Harry; Logan, Clint; Haskins, Jerry; Johansson, Erik; Perkins, Dwight; Hernandez, Jose M. et al.
Object Type: Report
System: The UNT Digital Library
Hot-Electron Tunneling sensors for high-resolution x-ray and gamma-ray spectroscopy (open access)

Hot-Electron Tunneling sensors for high-resolution x-ray and gamma-ray spectroscopy

Over the past 2 years, we have been studying the use of Hot Electron Tunneling sensors for use in high-energy-resolution x-ray and gamma-ray spectrometers. These sensors promise several advantages over existing cryogenic sensors, including simultaneous high count rate and high resolution capability, and relative ease of use. Using simple shadow mask lithography, we verified the basic principles of operation of these devices and discovered new physics in their thermal behavior as a function applied voltage bias. We also began to develop ways to use this new sensor in practical x-ray and gamma-ray detectors based on superconducting absorbers. This requires the use of quasiparticle trapping to concentrate the signal in the sensing elements.
Date: February 7, 1997
Creator: Mears, C.A.; Labov, S.E.; Frank, M. & Netel, H.
Object Type: Report
System: The UNT Digital Library
Thermal stability of electrodes in Lithium-ion cells (open access)

Thermal stability of electrodes in Lithium-ion cells

Differential scanning calorimetry (DSC) analysis was used to identify thermal reactions in Sony-type lithium-ion cells and to correlate these reactions with interactions of cell constituents and reaction products. An electrochemical half-cell was used to cycle the anode and cathode materials and to set the state-of-charge (SOC). Three temperature regions of interaction were identified and associated with the SOC (degree of Li intercalation) of the cell. Anodes were shown to undergo exothermic reactions as low as 80 C involving decomposition of the solid electrolyte interphase (SEI) layer. The LiPF{sub 6} salt in the electrolyte (EC:PC:DEC/1M LiPF{sub 6}) was seen to play an essential role in this reaction. DSC analysis of the anodes from disassembled Sony cells showed similar behavior to the half-cell anodes with a strong exotherm beginning in the 80 C--90 C range. Exothermic reactions were also observed in the 200 C--300 C region between the intercalated lithium anodes, the LiPF{sub 6} salt, and the PVDF binder. These reactions were followed by a high-temperature reaction region, 300 C--400 C, also involving the PVDF binder and the intercalated lithium anodes. Cathode exothermic reactions with the PVDF binder were observed above 200 C and increased with the SOC (decreasing Li content in …
Date: February 7, 2000
Creator: Roth, Emanuel P. & Nagasubramanian, Ganesan
Object Type: Article
System: The UNT Digital Library
Drift waves in stellarator geometry (open access)

Drift waves in stellarator geometry

Drift waves are investigated in a real three-dimensional stellarator geometry. A linear system, based on the cold ion fluid model and a ballooning mode formalism, is solved numerically in the geometry of the stellarator H1-NF. The spectra of stable and unstable modes, as well as localization, are discussed. The dependence of the spectrum of the unstable modes on the wavevector, plasma density variation, and the location in the plasma is presented.
Date: February 7, 2000
Creator: Persson, M.; Nadeem, M.; Lewandowski, J.L.V. & Gardner, H.J.
Object Type: Report
System: The UNT Digital Library
Investigation of gas flow in long and narrow channels (open access)

Investigation of gas flow in long and narrow channels

To minimize the viscous flow losses in a microsystem for chemical analysis, the authors have investigated gas flow in long capillary tubes and microchannels to characterize the flow behavior. Both experimental results and theoretical predictions indicate that gas flow in long and narrow channels, as in capillary tubes or rectangular channels, compressibility effect is very important. This leads to a higher mass flow rate than predicted by the incompressible flow model. Different computational fluid dynamics (CFD) codes have been applied to simulate this flow problem. While some existing CFD codes have difficulties to model this problem, other codes, such as MPSalsa, predict a converged and reasonably accurate solution. This difficulty may be caused by numerical solution technique in these computer codes being optimized for incompressible flow problems rather than for compressible low-speed flow problems.
Date: February 7, 2000
Creator: WONG,CHUNGNIN C.; ZOELLER,TRACIE L.; ADKINS,DOUGLAS R. & SHADID,JOHN N.
Object Type: Article
System: The UNT Digital Library
Improved performance of Li-ion cells under pulsed load using double-layer capacitors in a hybrid circuit mode (open access)

Improved performance of Li-ion cells under pulsed load using double-layer capacitors in a hybrid circuit mode

Electrical characteristics of hybrid power sources consisting of Li-ion cells and double-layer capacitors were studied at 25 C and {minus}20 C. The cells were initially evaluated for pulse performance and then measured in hybrid modes of operation where they were coupled with the high-power capacitors. Cells manufactured by Panasonic measured at 25 C delivered full capacities of 0.76 Ah for pulses up to 3A and cells from A and T delivered full capacities of 0.73 Ah for pulses up to 4A. Measured cell resistances were 0.15 ohms and 0.12 ohms, respectively. These measurements were repeated at {minus}20 C. Direct coupling of the cells and capacitors (coupled hybrid) using 10F Panasonic capacitors in a 8F series/parallel combination extended the full capacity pulse limits (3.0V threshold) to 5.6A for the Panasonic cells and to 9A for the A and T cells. A similar arrangement using 100F capacitors from Elna in a 60F combination increased the Panasonic cell limit to 10 A. Operation in an uncoupled hybrid mode using uncoupled cell/capacitor discharge allowed fill cell capacity usage at 25 C up to the capacitor discharge limit and showed a factor of 5 improvement in delivered capacity at {minus}20 C.
Date: February 7, 2000
Creator: Roth, Emanuel P. & Nagasubramanian, Ganesan
Object Type: Article
System: The UNT Digital Library
Short pulse laser-induced optical damage and fracto-emission of amorphous, diamond-like carbon (open access)

Short pulse laser-induced optical damage and fracto-emission of amorphous, diamond-like carbon

Short pulse laser damage and ablation of amorphous, diamond-like carbon films is investigated. Material removal is due to fracture of the film and ejection of large fragments, which exhibit a broadband emission of microsecond duration.
Date: February 7, 2000
Creator: Sokolowski-Tinten, K.; Von Der Linde, D.; Siegal, Michael P. & Overmyer, Donald L.
Object Type: Article
System: The UNT Digital Library
Variable operation of Hall thruster with multiple segmented electrodes (open access)

Variable operation of Hall thruster with multiple segmented electrodes

Variable plasma jet velocity with low beam divergence over a range of mass flow rates can be achieved through segmented electrode operation of Hall plasma accelerator. With the use of just a cathode side electrode at the cathode potential, the beam divergence can be decreased substantially, at some cost in efficiency. However, the additional use of an anode side electrode retains the same reduced plume divergence, but at efficiencies comparable to the non-segmented operation. The high efficiency persists also when the anode side electrode is biased at an intermediate potential, thus producing two-stage Hall accelerator operation.
Date: February 7, 2000
Creator: Fisch, N. J.; Raitses, Y.; Dorf, L. A. & Litvak, A. A.
Object Type: Report
System: The UNT Digital Library
Drift waves in general toroidal geometry (open access)

Drift waves in general toroidal geometry

A model, based on gyro-kinetic ions and fluid electrons, to study drift waves in low-beta [beta = (kinetic pressure)/(magnetic pressure)] stellarator plasmas is presented. The model equations are written in straight-field-line coordinates and are valid for arbitrary, fully three-dimensional configurations with closed, nested magnetic surfaces. An implicit method, coupled with a subcycling technique for the electrons, is used to solve the time-dependent, along-the-field-line equations. Numerical calculations are carried out for a 3-field-period toroidal heliac. The geometrical effects that enter the model equations are calculated and displayed in physical space using advanced visualization techniques.
Date: February 7, 2000
Creator: Lewandowski, J.L.V.
Object Type: Report
System: The UNT Digital Library
Functional design criteria, Project W-211, Initial Tank Retrieval Systems. Revision 1 (open access)

Functional design criteria, Project W-211, Initial Tank Retrieval Systems. Revision 1

This document provides the technical baseline for retrieval of waste from ten double-shell tanks in the SY, AN, AP, AW, AY, and AZ tank farms. In order to retrieve waste from these tanks, systems are needed to mix the sludge with the supernate and pump the waste mixture from the tank. For 101-SY, the existing mitigation pump will be used to mix the waste and Project W-211 will provide for waste removal. The retrieval scope for the other nine tanks includes both the waste mixing and removal functions.
Date: February 7, 1995
Creator: Rieck, C.A.
Object Type: Report
System: The UNT Digital Library