Hybrid charged-particle guide for studying (n, charged particle) reactions (open access)

Hybrid charged-particle guide for studying (n, charged particle) reactions

Charged-particle transport systems consisting of magnetic quadrupole lenses have been employed in recent years in the study of (n, charged particle) reactions. We have completed a new transport system that is based both on magnetic lenses as well as electrostatic fields. The magnetic focusing of this charged-particle guide is provided by six magnetic quadrupole lenses arranged in a CDCCDC sequence (in the vertical plane). The electrostatic field is produced by a wire at high voltage which stretches the length of the guide and is physically at the center of the magnetic axis. The magnetic lenses are used for charged particles above 5 MeV; the electrostatic guide is used for lower energies. This hybrid system possesses the excellent focusing and background rejection properties of other magnetic systems. For low energy charged-particles, the electrostatic transport avoids the narrow band-passes in charged-particle energy which are a problem with purely magnetic transport systems. This system is installed at the LLNL Cyclograaff facility for the study of (n, charged particle) reactions at neutron energies up to 35 MeV.
Date: August 25, 1982
Creator: Haight, R. C.; White, R. M. & Zinkle, S. J.
System: The UNT Digital Library
Tritium experience at RTNS-II (open access)

Tritium experience at RTNS-II

Neutrons are produced at the Rotating Target Neutron Source-II (RTNS-II) by deuteron bombardment of a rotating tritium target. Tritium is released from these targets into the accelerator vacuum system. The vacuum system exhaust is first scrubbed and then vented via the facility stack. Tritium emission from the facility in normal operation with vacuum system exhaust flowing through the scrubber is extremely low, <1 mCi/day. Releases from by-passing the tritium scrubber during roughing of the vacuum system and from accelerator maintenance account for nearly all of the annual 10 Ci release from the facility. Routine target changes have been the cause of most tritium uptake by personnel. A target shipping system has been devised for transport of these targets.
Date: April 25, 1980
Creator: Logan, C. M.; Davis, J. C.; Gibson, T. A.; Heikkinen, D. W.; Schumacher, B. J. & Singh, M. S.
System: The UNT Digital Library
Production of muons for fusion catalysis in a magnetic mirror configuration. Revision 1 (open access)

Production of muons for fusion catalysis in a magnetic mirror configuration. Revision 1

For muon-catalyzed fusion to be of practical interest, a very efficient means of producing muons must be found. We describe a scheme for producing muons that may be more energy efficient than any heretofore proposed. There are, in particular, some potential advantages of creating muons from collisions of high energy tritons confined in a magnetic mirror configuration. If one could catalyze 200 fusions per muon and employ a uranium blanket that would multiply the neutron energy by a factor of 10, one might produce electricity with an overall plant efficiency (ratio of electric energy produced to nuclear energy released) approaching 30%. One possible near term application of a muon-producing magnetic-mirror scheme would be to build a high-flux neutron source for radiation damage studies. The careful arrangement of triton orbits will result in many of the ..pi../sup -/'s being produced near the axis of the magnetic mirror. The pions quickly decay into muons, which are transported into a small (few-cm-diameter) reactor chamber producing approximately 1-MW/m/sup 2/ neutron flux on the chamber walls, using a laboratory accelerator and magnetic mirror. The costs of construction and operation of the triton injection accelerator probably introduces most of the uncertainty in the viability of this …
Date: July 25, 1986
Creator: Moir, R.W. & Chapline, G.F. Jr.
System: The UNT Digital Library
Supernovae, compact stars and nuclear physics (open access)

Supernovae, compact stars and nuclear physics

We briefly review the current understanding of supernova. We investigate the implications of rapid rotation corresponding to the frequency of the new pulsar reported in the supernovae remnant SN1987A. It places very stringent conditions on the equation of state if the star is assumed to be bound by gravity alone. We find that the central energy density of the star must be greater than 12 times that of nuclear density to be stable against the most optimistic estimate of general relativistic instabilities. This is too high for the matter to plausibly consist of individual hadrons. We conclude that the newly discovered pulsar, if its half-millisecond signals are attributable to rotation, cannot be a neutron star. We show that it can be a strange quark star, and that the entire family of strange stars can sustain high rotation under appropriate conditions. We discuss the conversion of a neutron star to strange star, the possible existence of a crust of heavy ions held in suspension by centrifugal and electric forces, the cooling and other features. 39 refs., 8 figs., 2 tabs.
Date: August 25, 1989
Creator: Glendenning, N.K.
System: The UNT Digital Library
Mirror theory applied to toroidal systems (open access)

Mirror theory applied to toroidal systems

Central features of a mirror plasma are strong departures from Maxwellian distribution functions, ambipolar potentials and densities which vary along a field line, and losses, and the mirror field itself. To examine these features, mirror theorists have developed analytical and numerical techniques to solve the Fokker-Planck equation, evaluate the potentials consistent with the resulting distribution functions, and assess the microstability of these distributions. Various combinations of mirror-plasma fetures are present and important in toroidal plasmas as well, particularly in the edge region and in plasmas with strong r.f. heating. In this paper we survey problems in toroidal plasmas where mirror theory and computational techniques are applicable, and discuss in more detail three specific examples: calculation of the toroidal generalization of the Spitzer-Haerm distribution function (from which trapped-particle effects on current drive can be calculated), evaluation of the nonuniform potential and density set up by pulsed electron-cyclotron heating, and calculation of steady-state distribution functions in the presence of strong r.f. heating and collisions. 37 refs., 3 figs.
Date: August 25, 1987
Creator: Cohen, R.H.
System: The UNT Digital Library
Improving the injectability of high-salinity brines for disposal or waterflooding operations (open access)

Improving the injectability of high-salinity brines for disposal or waterflooding operations

This work is part of a study conducted by Lawrence Livermore National Laboratory (LLNL) to improve the performance of brine injection wells at Gulf Coast Strategic Petroleum Reserve Sites. Our involvement established that granular media filtration, when used with proper chemical pretreatments, provides an effective and economical method for removing particulates from hypersaline brines. This treatment allows for the injection of 200,000 B/D with significantly increased well half-lives of 30 years.
Date: July 25, 1981
Creator: Raber, E.; Thompson, R.E. & Smith, F.H.
System: The UNT Digital Library
The soudan 2 experiment (open access)

The soudan 2 experiment

Soudan 2 is an 1100-ton tracking calorimeter which is being constructed to search for nucleon decay. The detector consists of finely segmented iron instrumented with drift tubes, and records three spatial coordinates and dE/dx for every gas crossing. Excellent event-reconstruction capability, particle identification, and muon sign and direction determination give superior rejection of the neutrino background to nucleon decay in many modes. The first 275 tons of Soudan 2 is operating and a charged-particle test beam calibration is under way. Construction is scheduled for completion in 1992. 4 refs., 6 figs., 2 tabs.
Date: May 25, 1989
Creator: Ayres, D.S.
System: The UNT Digital Library
Cancer risks and neutron RBE's from Hiroshima and Nagasaki (open access)

Cancer risks and neutron RBE's from Hiroshima and Nagasaki

The new radiation dose estimates for Hiroshima and Nagasaki are radiobiologically examined for compatability with other human and experimental data. The new doses show certain improvements over the original T65 doses. However, they suggest for chronic granulocytic leukemia, total malignancies, and chromosome aberrations, at neutron doses of 1 rad, RBEs in excess of 100, higher than expected from other findings. This and other indications suggest that either there are unrecognized systematic problems with the various radiobiological data, or the new doses are deficient in neutrons for Hiroshima, by a factor of about five. If in fact there were actually some 5-fold more dose from neutrons at Hiroshima than estimated by the new calculations, the RBEs would agree well with laboratory results, and other inconsistencies would largely disappear. Cancer risks are estimated for neutrons from the new doses and are compared with those estimated from radiobiologically reconciled doses (the new doses adjusted by adding approximately 5-fold more neutrons). The latter appear more reasonable. For low-LET radiation, cancer risk estimates are changed very little by the new dose estimates for Nagasaki.
Date: March 25, 1982
Creator: Dobson, R.L. & Straume, T.
System: The UNT Digital Library
Isotherms for the uranium-hydrogen system at temperatures of 700 to 1065/sup 0/C and pressures to 137. 89 MPa (open access)

Isotherms for the uranium-hydrogen system at temperatures of 700 to 1065/sup 0/C and pressures to 137. 89 MPa

Pressure vs composition (P-C) isotherms for the UH system for temperatuers of 700 to 1065/sup 0/C and pressures to 137.89 MPa are shown. The sample was contained in a vessel concentric and located within a secondary vessel. Plateau pressure at 1065/sup 0/C is 700 atm. The single-phase region on the hydrogen-rich side starts at a H/U ratio of 2.35. Physical property measurements showed a thermal conductivity, k, value of 0.003 cal/cm sec K, R/sub c/ = 50. Experimentally determined plateau pressures are compared with values obtained by other workers. The UH system retains broad, two-phase plateaus at temperatures to 1065/sup 0/C. The critical temperature must be above 1065/sup 0/C. 13 refs., 3 figs., 1 tab.
Date: June 25, 1985
Creator: Lakner, J. F.
System: The UNT Digital Library
Hydrodynamic effects in evaporating droplets (open access)

Hydrodynamic effects in evaporating droplets

The vaporization of a spherically symmetric liquid droplet homogeneously heated by a high-intensity laser pulse is investigated on the basis of a hydrodynamic description of the system composed of the vapor and ambient gas. In the limit of convective vaporization, the boundary conditions at the fluid-gas interface are formulated by using the notion of a Knudsen layer across which translational equilibrium is established. Numerical solutions to the hydrodynamic equations exhibit the existence of two shock waves propagating in opposite directions with respect to the contact discontinuity that separates the ambient gas and vapor. 17 refs., 6 figs.
Date: September 25, 1986
Creator: Armstrong, R.L. & Zardecki, A.
System: The UNT Digital Library
Radiation-effects limits on copper in superconducting magnets (open access)

Radiation-effects limits on copper in superconducting magnets

The determination of the response of copper stabilizers to neutron irradiation in fusion-reactor superconducting magnets requires information in four areas: (1) neutron flux and spectrum determination, (2) resistivity changes at zero field, (3) resistivity changes at field, and (4) the cyclic irradiation and annealing. Applications of our current understanding of the limits of copper stabilizers in fusion-reactor designs are explored in two examples. Recommendations for future additions to the data base are discussed.
Date: May 25, 1983
Creator: Guinan, M.W.
System: The UNT Digital Library
Ion chamber gamma burst detector (open access)

Ion chamber gamma burst detector

A gamma ray burst detector of x-ray photons 2 to 10 keV is designed to maximize area, 100 m/sup 2/, and sensitivity, 10/sup -10/ ergs cm/sup -2/ s/sup 1/2/ modest directionality, 2 x 10/sup -4/ sr, and minimize thickness, 3 mg cm/sup -2/, as a plastic space balloon ion chamber. If the log N - log S curve for gamma bursts extends as the -3/2 power, the sensitivity is limited by gamma-burst peak overlap in time so that the question of the size spectrum and isotropy is maximally tested. Supernova type I prompt x-ray bursts of congruent to 3-ms duration should be detected at a rate of several per day from supernova at a distance greater than 100 Mpc.
Date: August 25, 1981
Creator: Colgate, S. A.
System: The UNT Digital Library
Pulse power for the RAPIER B Amplifier KrF laser system (open access)

Pulse power for the RAPIER B Amplifier KrF laser system

The RAPIER B Amplifier electron beam system has been completed and produces 36kJ of 450 keV electrons in a 150 ns pulse to be used for pumping a KrF laser amplifier. The operating characteristics of the system have been studied. The efficiency of conversion of energy stored in the Marx generator to electron beam output is 72 +- 3% including an 89% designed transfer efficiency. The system is triggered electrically with a 150 ns delay from the command trigger to machine output. The rms jitter for the six individual modules range from 1.6 to 3.9 ns and the average timing difference between the earliest and latest module output is 12 ns. Film dosimetry indicates no observable interaction between the magnetically isolated beams in the module diodes and fluorescence measurements do not indicate strong interaction in the gas filled laser cell. Current probe measurements show no significant change in beam size during the output pulse. Energy deposition profiles agree reasonably with Monte Carlo calculations up to pressures of 1.5 atm.
Date: May 25, 1983
Creator: Schlitt, L. G.
System: The UNT Digital Library
Spatially resolved x-ray laser spectra and demonstration of gain in nickel-like systems (open access)

Spatially resolved x-ray laser spectra and demonstration of gain in nickel-like systems

A recent series of experiments have provided spatially resolved near field images of several candidate x-ray lasing transition in neon-like, nickel-like, and hydrogen-like ions from laser-produced plasmas. From these time-gated, spatially, and spectrally resolved measurements the source size for the J = 0 - 1 and the J = 2 - 1 transitions in Ne-like selenium have been determined. Source regions as small as 50 ..mu..m have been observed on transitions with gain-length products >9. In addition, we have obtained the first experimental evidence for the amplification of spontaneous emission in the nickel-like ions of europium and ytterbium. Gains of order 1 cm/sup -1/ and gain-length products of up to 3.8 are observed on the J = 0 - 1, 4d-4p transitions in Eu + 35 at 65.26 and 71.00 A. Analogous transitions in Yb = +42 have been identified and some evidence for ASE has been observed. 7 refs., 11 figs.
Date: September 25, 1987
Creator: Whelan, D. A.; Keane, C. J.; MacGowan, B. J.; Matthews, D. L.; Trebes, J. E. & Eckart, M. J.
System: The UNT Digital Library
Confinement and the Pomeron (open access)

Confinement and the Pomeron

The importance of confinement for obtaining a unitary high-energy limit for QCD is discussed. Minijets'' are argued to build up non-unitary behavior{endash}when k{sub T} {gt} {Lambda} is imposed. For minijets to mix with low k{sub T} Pomeron Field Theory describing confinement, and give consistent asymptotic behavior, new quarks'' must enter the theory above the minijet transverse momentum scale. The Critical Pomeron is the resulting high-energy limit. 22 refs.
Date: September 25, 1989
Creator: White, A.R.
System: The UNT Digital Library
Tritium management in fusion synfuel designs (open access)

Tritium management in fusion synfuel designs

Two blanket types are being studied: a lithium-sodium pool boiler and a lithium-oxide- or lithium-sodium pool boiler and a lithium-oxide- or aluminate-microsphere moving bed. For each, a wide variety of current technology was considered in handling the tritium. Here, we show the pool boiler with the sulfur-iodine thermochemical cycle first developed and now being piloted by the General Atomic Company. The tritium (T/sub 2/) will be generated in the lithium-sodium mixture where the concentration is approx. 10 ppM and held constant by a scavenging system consisting mainly of permeators. An intermediate sodium loop carries the blanket heat to the thermochemical cycle, and the T/sub 2/ in this loop is held to 1 ppM by a similar scavenging system. With this design, we have maintained blanket inventory at 1 kg of tritium, kept thermochemical cycle losses to 5 Ci/d and environmental loss to 10 Ci/d, and held total plant risk inventory at 7 kg tritium.
Date: April 25, 1980
Creator: Galloway, T.R.
System: The UNT Digital Library
Build-up of tritium in a liquid-lithium breeding blanket for an inertial-confinement-fusion chamber (open access)

Build-up of tritium in a liquid-lithium breeding blanket for an inertial-confinement-fusion chamber

The build-up of tritium in a liquid lithium breeding blanket for an ICF chamber has been examined. The break-even time is found to decrease both the increasing tritium breeding ratio and increasing values of ..cap alpha.., the fraction of unburned tritium absorbed in lithium. The break-even inventory also decreased with increasing breeding ratio but increases with increasing values ..cap alpha... For a molten-salt extraction process, the steady-state tritium inventory in lithium is inversely proportional to lithium flow rate through the extraction system. The lithium flow rate through the tritium extraction system required to maintain a given tritium concentration increases with increasing values of ..cap alpha...
Date: August 25, 1981
Creator: Meier, W. R.
System: The UNT Digital Library
Production of muons for fusion catalysis in a magnetic mirror configuration (open access)

Production of muons for fusion catalysis in a magnetic mirror configuration

One possible near term application of a muon-producing magnetic-mirror scheme would be to build a high-flux neutron source for radiation damage studies. The careful arrangement of triton orbits will result in many of the ..pi../sup -/s being produced near the axis of the magnetic mirror. The pions quickly decay into muons, which are transported into a small (few-cm-diameter) reactor chamber producing approximately 1-MW/m/sup 2/ neutron flux on the chamber walls, using a laboratory accelerator and magnetic mirror. The costs of construction and operation of the triton injection accelerator probably introduces most of the uncertainty in the viability of this scheme. If a 10-..mu..A, 600 MeV neutral triton accelerator could be built for less than $100 million and operated cheaply enough, one might well bring muon-catalyzed fusion into practical use.
Date: June 25, 1986
Creator: Moir, R.W. & Chapline, G.F. Jr.
System: The UNT Digital Library
Fokker-Planck calculations of electron cyclotron resonant heating (ECRH) in mirror geometry (open access)

Fokker-Planck calculations of electron cyclotron resonant heating (ECRH) in mirror geometry

A time dependent, bounce-averaged Fokker-Planck code, with quasi-linear diffusion at fundamental and second harmonic frequencies, has been used to study cold plasma trapping and heating of hot electrons in mirror geometry. Both electron-electron and electron-ion Coulomb collisions are included. The code can model either cavity heating (electric field throughout cavity as in EBT) or beam controlled heating (electric field spatially restricted as in the TMX-Upgrade tandem mirror). The heating method has implications for the equilibrium energy and anisotropy of the hot electrons. In TMX-Upgrade, off-midplane heating at the second harmonic in the thermal barrier is planned as a means to control anisotropy (T/sub parallel//T/sub perpendicular/. By spatially limiting (limit in B) the microwave beam and with strong single-pass absorption, the mean hot electron energy may also be controlled since the heating rate decreases at high energy due to the relativistic mass shift of the resonance to higher magnetic field.
Date: November 25, 1981
Creator: Stallard, B. W.; Matsuda, Y. & Nevins, W. M.
System: The UNT Digital Library
Simultaneous evaluation of interrelated cross sections by generalized least-squares and related data file requirements (open access)

Simultaneous evaluation of interrelated cross sections by generalized least-squares and related data file requirements

Though several cross sections have been designated as standards, they are not basic units and are interrelated by ratio measurements. Moreover, as such interactions as /sup 6/Li + n and /sup 10/B + n involve only two and three cross sections respectively, total cross section data become useful for the evaluation process. The problem can be resolved by a simultaneous evaluation of the available absolute and shape data for cross sections, ratios, sums, and average cross sections by generalized least-squares. A data file is required for such evaluation which contains the originally measured quantities and their uncertainty components. Establishing such a file is a substantial task because data were frequently reported as absolute cross sections where ratios were measured without sufficient information on which reference cross section and which normalization were utilized. Reporting of uncertainties is often missing or incomplete. The requirements for data reporting will be discussed.
Date: October 25, 1984
Creator: Poenitz, W.P.
System: The UNT Digital Library
Immobilization of Savannah River high-level wastes in SYNROC: results from performance tests (open access)

Immobilization of Savannah River high-level wastes in SYNROC: results from performance tests

Large samples (up to 15cm diameter) of SYNROC D containing simulated Savannah River (SRL) waste sludge have been prepared and performance tested. Waste loadings of 60 to 65 wt% for the SRL composite sludge have been achieved; this corresponds to a waste concentration (volumetric) loading of approximately 2.3 to 2.5 g/cm/sup 3/. A typical SYNROC D sample has a density of about 4.0 g/cm/sup 3/ with less than 0.2% porosity. The compressive and flexural strengths of SYNROC D are 51,200 and 9400 psi, respectively and Young's Modulus is 20.1 x 10/sup 6/ psi by ultrasonic measurement. The quantity of respirable fines (less than 10 ..mu..m) generated during a constant energy density impact (10J/cm/sup 3/) was less than 0.16 wt%. Values for the thermal conductivity (22/sup 0/C) and the thermal expansion coefficient (22 to 950/sup 0/C) were measured to be 1.7 W/m.K and 11 x 10/sup -6/ K/sup -1/, respectively.
Date: September 25, 1981
Creator: Campbell, J. H.; Hoenig, C. L.; Bazan, F.; Ryerson, F. J. & Rozsa, R. B.
System: The UNT Digital Library
Mirror theory applied to toroidal systems (open access)

Mirror theory applied to toroidal systems

Central features of a mirror plasma are strong departures from Maxwellian distribution functions, ambipolar potentials and densities which vary along a field line, end losses, and the mirror field itself. To examine these features, mirror theorists have developed analytical and numerical techniques to solve the Fokker-Planck equation, evaluate the potentials consistent with the resulting distribution functions, and assess the microstability of these distributions. Various combinations of mirror-plasma features are present and important in toroidal plasmas as well, particularly in the edge region and in plasmas with strong rf heating. In this paper we survey problems in toroidal plasmas where mirror theory and computational techniques are applicable, and discuss in more detail three specific examples: calculation of the toroidal generalization of the Spitzer-Haerm distribution function (from which trapped-particle effects on current drive can be calculated), evaluation of the nonuniform potential and density set up by pulsed electron-cyclotron heating, and calculation of steady-state distribution functions in the presence of strong rf heating and collisions. 37 refs.
Date: August 25, 1987
Creator: Cohen, R.H.
System: The UNT Digital Library
System for intelligent teleoperation research (open access)

System for intelligent teleoperation research

The Automation Technology Branch of NASA Langley Research Center is developing a research capability in the field of artificial intelligence, particularly as applicable in teleoperator/robotics development for remote space operations. As a testbed for experimentation in these areas, a system concept has been developed and is being implemented. This system, termed DAISIE (Distributed Artificially Intelligent System for Interacting with the Environment), interfaces the key processes of perception, reasoning, and manipulation by linking hardware sensors and manipulators to a modular artificial intelligence (AI) software system in a hierarchical control structure. Verification experiments have been performed: one experiment used a blocksworld database and planner embedded in the DAISIE system to intelligently manipulate a simple physical environment; the other experiment implemented a joint-space collision avoidance algorithm. Continued system development is planned.
Date: October 25, 1983
Creator: Orlando, N.E.
System: The UNT Digital Library
Soudan 2 as a long baseline neutrino detector (open access)

Soudan 2 as a long baseline neutrino detector

In a nine month run with a 150 GeV proton beam and a conventional double horn neutrino beam aimed at the Soudan 2 detector, a search could be made for neutrino oscillations in the mode /nu//sub /mu// /yields/ /nu//sub /tau//. If evidence for oscillations is not found, new limits could be set extending the /Delta/m/sup 2/ excluded region from .3 eV/sup 2/ to .004 eV/sup 2/ at 90% confidence level. 7 refs., 4 figs.
Date: May 25, 1989
Creator: Goodman, M.
System: The UNT Digital Library