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Shock tube study of the reactions of the hydroxyl radical with combustion species and pollutants. Final report

Description: Shock heating t-butyl hydroperoxide behind a reflected shock wave has proved to be as a convenient source of hydroxyl radicals at temperatures near 1000 K. We applied this technique to the measurement of reaction rate coefficients of OH with several species of interest in combustion chemistry, and developed a thermochemical kinetics/transition state theory (TK-TST) model for predicting the temperature dependence of OH rate coefficients.
Date: February 1, 1998
Creator: Cohen, N. & Koffend, J.B.
Partner: UNT Libraries Government Documents Department

[Utilizing the ultraintense JanUSP laser at LLNL]. 99-ERD-049 Final LDRD Report

Description: Recent advances in laser and optical technologies have now enabled the current generation of high intensity, ultrashort-pulse lasers to achieve focal intensities of 10{sup 20}-10{sup 21} W/cm{sup 2} in pulse durations of 100-500fs. These ultraintense laser pulses are capable of producing highly relativistic plasma states with densities, temperatures, and pressures rivaling those found in the interiors of stars and nuclear weapons. Utilizing the ultraintense 100TW JanUSP laser at LLNL we have explored the possibility of ion shock heating small micron-sized plasmas to extremely high energy densities approaching 1GJ/g on timescales of a few hundred femtoseconds. The JanUSP laser delivers 10 Joules of energy in a 100fs pulse in a near diffraction-limited beam, producing intensities on target of up to 10{sup 21}W/cm{sup 2}. The electric field of the laser at this intensity ionizes and accelerates electrons to relativistic MeV energies. The sudden ejection of electrons from the focal region produces tremendous electrostatic forces which in turn accelerate heavier ions to MeV energies. The predicted ion flux of 1 MJ/cm{sup 2} is sufficient to achieve thermal equilibrium conditions at high temperature in solid density targets. Our initial experiments were carried out at the available laser contrast of 10{sup -7} (i.e. the contrast of the amplified spontaneous emission (ASE), and of the pre-pules produced in the regenerative amplifier). We used the nuclear photoactivation of Au-197 samples to measure the gamma production above 12MeV-corresponding to the threshold for the Au-197(y,n) reaction. Since the predominant mechanism for gamma production is through the bremsstrahlung emission of energetic electrons as they pass through the solid target we were able to infer a conversion yield of several percent of the incident laser energy into electrons with energies >12MeV. This result is consistent with the interaction of the main pulse with a large pre-formed plasma. The contrast of the ...
Date: April 17, 2002
Creator: Patel, P K; Price, D F; Mackinnon, A J & Springer, P T
Partner: UNT Libraries Government Documents Department

Simulation of Comet Impact and Survivability of Organic Compounds

Description: Comets have long been proposed as a potential means for the transport of complex organic compounds to early Earth. For this to be a viable mechanism, a significant fraction of organic compounds must survive the high temperatures due to impact. We have undertaken three-dimensional numerical simulations to track the thermodynamic state of a comet during oblique impacts. The comet was modeled as a 1-km water-ice sphere impacting a basalt plane at 11.2 km/s; impact angles of 15{sup o} (from horizontal), 30{sup o}, 45{sup o}, 65{sup o}, and 90{sup o} (normal impact) were examined. The survival of organic cometary material, modeled as water ice for simplicity, was calculated using three criteria: (1) peak temperatures, (2) the thermodynamic phase of H{sub 2}O, and (3) final temperature upon isentropic unloading. For impact angles greater than or equal to 30{sup o}, no organic material is expected to survive the impact. For the 15{sup o} impact, most of the material survives the initial impact and significant fractions (55%, 25%, and 44%, respectively) satisfy each survival criterion at 1 second. Heating due to deceleration, in addition to shock heating, plays a role in the heating of the cometary material for nonnormal impacts. This effect is more noticeable for more oblique impacts, resulting in significant deviations from estimates using scaling of normal impacts. The deceleration heating of the material at late times requires further modeling of breakup and mixing.
Date: July 18, 2007
Creator: Liu, B T; Lomov, I N; Blank, J G & Antoun, T H
Partner: UNT Libraries Government Documents Department

Complete equation of state for [beta]-HMX and implications for initiation

Description: A thermodynamically consistent equation of state for {beta}-HMX, the stable ambient polymorph of HMX, is developed that fits isothermal compression data and the temperature dependence of the specific heat computed from molecular dynamics. The equation of state is used to assess hot-spot conditions that would result from hydrodynamic pore collapse in a shock-to-detonation transition. The hot-spot temperature is determined as a function of shock strength by solving two Riemann problems in sequence: first for the velocity and density of the jet formed when the shock overtakes the pore, and second for the stagnation state when the jet impacts the far side of the pore. For a shock pressure below 5 GPa, the stagnation temperature from the jet is below the melt temperature at ambient pressure and hence insufficient for rapid reaction. Consequently for weak shocks a dissipation mechanism in addition to shock heating is needed to generate hot spots. When the stagnation temperature is sufficiently high for rapid reaction, the shock emanating from the hot spot is computed, assuming aconstant volume burn. For initial shocks below 20 GPa, the temperature behind the second shock is below 1000K and would not propagate a detonation wave. This analysis, based solely on the equation of state of the explosive, can serve as a check on mesoscale simulations of initiation in a plastic-bonded explosive.
Date: January 1, 2003
Creator: Sewell, T. D. (Thomas D.) & Menikoff, Ralph
Partner: UNT Libraries Government Documents Department


Description: A Molybdenum--{sup 182}Tungsten (Mo-{sup 182}W) alloy was specified for an application that would ultimately result in the measurement of temperature and particle velocity during the steady state time following the shock loading of various materials. The {sup 182}W isotope provides a tag for the analysis of neutron resonance line shape from which the temperature may be calculated. The material was specified to have 1.8 atom percent W, with W-rich regions no larger than 1 {micro}m in size. Both the composition and W distribution were critical to the experiment. Another challenge to the processing was the very small quantity of {sup 182}W material available for the synthesis of the alloy. Therefore, limited fabrication routes were available for evaluation. Several synthesis and processing routes were explored to fabricate the required alloy components. First, precipitation of W onto Mo powder using ammonium metatungstate was investigated for powder synthesis followed by uniaxial hot pressing. Second, mechanical alloying (MA) followed by hot isostatic pressing (HIP) and warm forging was attempted. Finally, arc-melting techniques followed by either hot rolling or crushing the alloyed button into powder and consolidation were pursued. The results of the processing routes and characterization of the materials produced will be discussed.
Date: September 1, 1999
Partner: UNT Libraries Government Documents Department


Description: A conceptual design is presented for a high power pion production target, based on a rotating band of inconel alloy 718, that is intended to provide a back-up targetry option for the Neutrino Factory Study II. The target band has a 2.5 m radius and has an I-beam cross section that is 6 cm high and with a 0.6 cm thick webbing. The pion capture scenario and proton beam parameters are as specified for the Study II base-line targetry option, i.e. capture into a 20 Tesla tapered solenoidal channel with proton beam fills at 2.5 Hz containing 6 short bunches, each spaced by 20 milliseconds, of 1.67 x 10{sup 13} 24 GeV protons. The target is continuously rotated at 1 m/s to Carey heat away from the production region and through a water cooling tank. The mechanical layout and cooling setup are described and results are presented from realistic MARS Monte Carlo computer simulations of the pion yield and energy deposition in the target and from ANSYS finite element calculations for the corresponding shock heating stresses.
Date: May 4, 2001
Partner: UNT Libraries Government Documents Department


Description: A conceptual design is presented for a high power pion production target for muon colliders that is based on a rotating metal band. Three candidate materials are considered for the target band: inconel alloy 718, titanium alloy 6Al-4V grade 5 and nickel. A pulsed proton beam tangentially intercepts a chord of the target band that is inside a 20 Tesla tapered solenoidal magnetic pion capture channel similar to designs previously considered for muon colliders and neutrino factories. The target band has a radius of 2.5 meters and is continuously rotated at approximately 1 m/s to carry heat away from the production region and through a water cooling tank. The mechanical layout and cooling setup of the target are described, including the procedure for the routine replacement of the target band. A rectangular band cross section is assumed, optionally with I-beam struts to enhance stiffness and minimize mechanical vibrations. Results are presented from realistic MARS Monte Carlo computer simulations of the pion yield and energy deposition in the target and from ANSYS finite element calculations for the corresponding shock heating stresses. The target scenario is found to perform satisfactorily and with conservative safety margins for multi-MW pulsed proton beams.
Date: January 18, 2002
Partner: UNT Libraries Government Documents Department

Virialization Heating in Galaxy Formation

Description: In a hierarchical picture of galaxy formation virialization continually transforms gravitational potential energy into kinetic energies in the baryonic and dark matter. For the gaseous component the kinetic, turbulent energy is transformed eventually into internal thermal energy through shocks and viscous dissipation. Traditionally this virialization and shock heating has been assumed to occur instantaneously allowing an estimate of the gas temperature to be derived from the virial temperature defined from the embedding dark matter halo velocity dispersion. As the mass grows the virial temperature of a halo grows. Mass accretion hence can be translated into a heating term. We derive this heating rate from the extended Press Schechter formalism and demonstrate its usefulness in semi-analytical models of galaxy formation. Our method is preferable to the traditional approaches in which heating from mass accretion is only modeled implicitly through an instantaneous change in virial temperature. Our formalism can trivially be applied in all current semi-analytical models as the heating term can be computed directly from the underlying merger trees. Our analytic results for the first cooling halos and the transition from cold to hot accretion are in agreement with numerical simulations.
Date: January 17, 2007
Creator: Wang, P. (KIPAC, Menlo Park) & Abel, T. (Santa Barbara, KITP)
Partner: UNT Libraries Government Documents Department

Opacity measurements in shock-generated argon plasmas

Description: Dense plasmas having uniform and constant density and temperature are generated by passage of a planar shock wave through gas. The opacity of the plasma is accurately measured versus wavelength by recording the risetime of emitted light. This technique is applicable to a wide variety of species and plasma conditions. Initial experiments in argon have produced plasmas with 2 eV temperatures, 0.004--0.04 g/cm{sup 3} densities, and coupling parameters {Gamma} {approximately}0.3--0.7. Measurements in visible light are compared with calculations using the HOPE code. An interesting peak in the capacity at 400 nm is observed for the first time and is identified with the 4s-5p transition in excited neutral argon atoms.
Date: July 1, 1993
Creator: Erskine, D.
Partner: UNT Libraries Government Documents Department

Shock physics code research at Sandia National Laboratories; massively parallel computers and advanced algorithms

Description: Shock physics researchers at Sandia are working in two areas: massively parallel computing and improved solution algorithms. Our goal is predictive modeling of large, three-dimensional problems. We will discuss the goals, rationale and status of this work.
Date: April 1, 1996
Creator: McGlaun, J.M.; Peery, J.S. & Hertel, E.S.
Partner: UNT Libraries Government Documents Department

Design and fabrication of a radially-fed implosion heating coil

Description: A radially-fed implosion heating coil has been designed and fabricated at the Los Alamos Scientific Laboratory. The M arshall coil is a copper-plate-on-epoxy-substrate coil designed to utilize up to 200- kV to produce a 1-T magnetic field in a 20-cm bore with a risetime of no more than 250-ns. The design and fabrication process of this coil and the design of the high-voltage stand for the Marshall coil are discussed.
Date: January 1, 1977
Creator: Hansborough, L.D.; Dickinson, J.M.; Melton, J.G. & Nunnally, W.C.
Partner: UNT Libraries Government Documents Department

Kaliski's explosive driven fusion experiments

Description: An experiment performed by a group in Poland on the production of DD fusion neutrons by purely explosive means is discussed. A method for multiplying shock velocities ordinarily available from high explosives by a factor of ten is described, and its application to DD fusion experiments is discussed.
Date: January 1, 1979
Creator: Marshall, J.
Partner: UNT Libraries Government Documents Department

Target dynamics and thermonuclear burn, Part I

Description: The interaction between projectiles and targets in an impact fusion reactor system is considered. Heating by plane shock waves in DT is discussed. The condition for ignition is estimated and it is concluded that simple one-dimensional shock heating is unsuitable for fusion power production. It is suggested that shock heating followed by further compession would be an improvement.
Date: January 1, 1979
Creator: Marshall, J.
Partner: UNT Libraries Government Documents Department

Energy losses in conductors carrying very high currents

Description: Conductors carrying very high currents show losses of an electromagnetic and a shock compression nature. Electromagnetic losses (joule heating in the skin layer, magnetic flux diffusion) scale as H/sup 3/ or (I/a)/sup 3/, where H is the self magnetic field of the current and I/a is the current divided by conductor - periphery; shock losses scale as H/sup 4/ or H/sup 3/ ((I/a)/sup 4/ or (I/a)/sup 3/) depending on the magnitude of I. In experiments where electrical energy must be converged from a large pulsed power supply to a small load, these losses can account for half the orignal energy and limit the magnitude of the energy per unit volume in the load. These considerations may be important for the study of material properties at high energy density.
Date: January 1, 1981
Creator: Singer, S. & Hunter, R.O.
Partner: UNT Libraries Government Documents Department

Electron-temperature requirements for neutralized inertial-confinement-fusion light-ion beams

Description: Because of their large self-space-charge fields, light ion beam drivers of energy and power sufficient to achieve inertial confinement fusion (ICF) cannot be focused on a small fuel pellet unless neutralized. Even if initially neutralized with comoving electrons, these beams will not stay neutralized and focus during propagation through a vacuum chamber unless the initial thermal energy of the neutralizing electrons is sufficiently small. In this paper we discuss the effects which contribute to the effective initial temperature of the neutralizing electrons, including compressional shock heating. We also employ a simple heuristic model to construct envelope equations which govern axial as well as radial beam compression and use them to predict the largest initial electron temperature consistent with the required beam compression. This temperature for typical light ion beam systems is about ten eV - a temperature which may be possible to achieve.
Date: January 1, 1981
Creator: Lemons, D.S.
Partner: UNT Libraries Government Documents Department

Chemical equilibrium calculations for the high pressure and temperature dissociation of liquid nitrogen

Description: Calculations are reported for the equation-of-state properties of shock-compressed liquid nitrogen. The statistical mechanical, chemical equilibrium calculations, which allow for the simultaneous presence of both the diatomic and monatomic forms of nitrogen, show good agreement with recent dynamic experiments.
Date: July 1, 1987
Creator: Hamilton, D.C. & Ree, F.H.
Partner: UNT Libraries Government Documents Department

Infrared Images of Shock-Heated Tin

Description: High-resolution, gated infrared images were taken of tin samples shock heated to just below the 505 K melting point. Sample surfaces were either polished or diamond-turned, with grain sizes ranging from about 0.05 to 10 mm. A high explosive in contact with a 2-mm-thick tin sample induced a peak sample stress of 18 GPa. Interferometer data from similarly-driven tin shots indicate that immediately after shock breakout the samples spall near the free (imaged) surface with a scab thickness of about 0.1 mm.
Date: September 1, 2004
Creator: McCluskey, Craig W.; Wilke, Mark D.; Turley, William D.; Stevens, Gerald D.; Veeser, Lynn R. & Grover, Michael
Partner: UNT Libraries Government Documents Department

Linear magnetic fusion: summary of Seattle workshop

Description: The linear-geometry magnetic confinement concept is among the oldest used in the study of high-temperature plasmas. However, it has generally been discounted as a suitable approach for demonstrating controlled thermonuclear fusion because rapid losses from the plasma column ends necessitate very long devices. Further, the losses and how to overcome them have not yet received parametric experimental study, nor do facilities exist with which such definitive experiments could be performed. Nonetheless, the important positive attribute, simplicity, together with the appearance of several ideas for reducing end losses have provided motivation for continued research on linear magnetic fusion (LMF). These motivations led to the LMF workshop, held in Seattle, March 9--11, 1977, which explored the potential of LMF as an alternate approach to fusion. A broad range of LMF aspects were addressed, including radial and axial losses, stability and equilibrium, heating, technology, and reactor considerations. The conclusions drawn at the workshop are summarized.
Date: December 1, 1977
Partner: UNT Libraries Government Documents Department

Shock wave compression and metallization of simple molecules

Description: In this paper we combine shock wave studies and metallization of simple molecules in a single overview. The unifying features are provided by the high shock temperatures which lead to a metallic-like state in the rare gases and to dissociation of diatomic molecules. In the case of the rare gases, electronic excitation into the conduction band leads to a metallic-like inert gas state at lower than metallic densities and provides information regarding the closing of the band gap. Diatomic dissociation caused by thermal excitation also leads to a final metallic-like or monatomic state. Ina ddition, shock wave data can provide information concerning the short range intermolecular force of the insulator that can be useful for calculating the metallic phase transition as for example in the case of hydrogen. 69 refs., 36 figs., 2 tabs.
Date: March 1, 1988
Creator: Ross, M. & Radousky, H.B.
Partner: UNT Libraries Government Documents Department

Electric breeding of fissile materials with low Q, non-mainline fusion drivers

Description: The application of two novel fusion reactor concepts to the production of fissile fuel for existing and planned fission reactors has been shown to be technically feasible and potentially economically competitive. The performance required of fusion based breeders has been derived in terms of the fusion gain, blanket neutron and energy multiplication, and the performance and economic parameters of the fission reactors. Electron beam heated, linear solenoid confined plasmas were one concept which showed the most promise. A shock heated, wall confined reactor also appeared attractive for breeding.
Date: October 1, 1977
Creator: Benford, J.; Bailey, V.; Oliver, D.; DiCapua, M.; Cooper, R.; Lopez, O. et al.
Partner: UNT Libraries Government Documents Department

Coherent anti-Stokes Raman scattering in benzene and nitromethane shock-compressed to 10 GPa

Description: The frequency shifts of the ring-stretching mode of shock-compressed liquid benzene and the CN stretching mode of nitromethane have been measured using coherent anti-Stokes Raman scattering. Shock pressures up to 11 GPa were achieved using a two-stage light gas gun. The frequency shifted Raman signal was generated using single pulse Nd:YAG and broadband-type lasers. 16 refs., 3 figs.
Date: January 1, 1985
Creator: Schmidt, S.C.; Moore, D.S.; Shaner, J.W.; Shampine, D.L. & Holt, W.T.
Partner: UNT Libraries Government Documents Department