| Portable Neutron Source |
30 MAY 2008 |
50 pages |
| Authors:
J. Davis; G. M. Petrov; NAVAL RESEARCH LAB WASHINGTON DC PLASMA PHYSICS DIV
|
 | The angular distribution of neutrons formed in nuclear fusion reactions of a high-energy deuteron beam with a deuterated polyethylene (CD2) was investigated with a Monte Carlo ion beam-target deposition model. The initial conditions were obtained from a two-dimensional particle-in-cell laser-target deposition model. The neutron yield and its angular distribution were studied as a function of peak laser intensity, laser pulse duration and primary target thickness. The proposed scheme for neutron ... |
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| On Optimizing the Configuration of Time-Transfer Links Used to Generate TAI |
2007 |
14 pages |
| Authors:
D. Matsakis; F. Arias; A. Bauch; J. Davis; T. Gotoh; M. Hosokawa; D. Piester; NAVAL OBSERVATORY WASHINGTON DC
|
| This is the report of Study Group II of the Working Group on TAI, which was formed to study two of the three proposals in the BIPM Technical Memo 132, circulated in December, 2004. It is recommended that TAI be generated through combinations of Two Way Satellite Time and Frequency Transfer (TWSTFT) links and GPS links. It is assumed that Study Group I will not oppose acceptance of the first ... |
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| Alternate Approaches to Laser Guided Discharges |
19 APR 2006 |
25 pages |
| Authors:
J. Davis; R. E. Terry; G. M. Petrov; A. L. Velikovich; NAVAL RESEARCH LAB WASHINGTON DC
|
| We propose a novel use of laser induced breakdown channels to establish a transmission line through air, which terminates at a distant load object. |
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| Z-Pinch Plasma Neutron Sources |
24 MAR 2006 |
54 pages |
| Authors:
A. L. Velikovich; R. W. Clark; J. Davis; Y. K. Chono; C. Deeney; C. A. Coverdale; C. Ruiz; G. Cooper; J. Franklin; L. I. Rudakov; SANDIA NATIONAL LABS ALBUQUERQUE NM
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| A deuterium gas-puff load imploded by a multi-MA current driver, from a large initial diameter could be a powerful source of fusion neutrons, a plasma neutron source. Unlike the beam-target neutrons produced in Z-pinch plasmas in the 1950s and deuterium-fiber experiments in the 1980s, the neutrons generated in deuterium gas-puffs, with current levels achieved in recent experiments on the SNL Z facility, could contain a substantial fraction of thermonuclear origin. ... |
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| On Optimizing the Configuration of Time-Transfer Links Used to Generate TAI |
2006 |
8 pages |
| Authors:
D. Matsakis; F. Arias; A. Bauch; J. Davis; T. Gotoh; M. Hosokawa; D. Piester; NAVAL OBSERVATORY WASHINGTON DC
|
| Recent work on the uncertainties of [UTC-UTC(kappa)] has made it possible to quantify the effects of different configurations of the time-transfer links used to generate International Atomic Time (TAI). The optimal topology depends upon the magnitude and character of the time-transfer noise of the relevant systems, the correlations between the time-transfer links, the required degree of robustness, the operational practices and equipment at pivot and crossover sites, and the operational ... |
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| Computed Tomography, |
1994 |
|
| Authors:
P. Wells; J. Davis; M. Morgan
|
 | X-ray or gamma-ray transmission computed tomography (CT) is a powerful non-destructive evaluation (NDE) technique that produces two-dimensional cross-sectional images of an object without the need to physically section it. CT is also known by the acronym CAT, for computerised axial tomography. This review article presents a brief historical perspective on CT, its current status and the underlying physics. The mathematical fundamentals of computed tomography are developed for the simplest transmission ... |
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| FIBER COATINGS FOR SAPPHIRE-REINFORCED ALUMINA COMPOSITES |
1993 |
|
| Authors:
J. Davis; A.G. Evans
|
| The goal of this investigation was to identify and develop fiber coatings for high temperature sapphire/alumina composites. Coatings were evaluated on a chemical compatibility and mechanical properties basis. In particular, acceptable coatings protect fibers from chemical reaction at high temperatures and encourage fiber debonding and sliding, behaviors necessary for toughness enhancement in brittle matrix composites. This study focused on determining the suitability of a variety of refractory materials as coatings ... |
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| Spectral Hole Burning Between 2 K and Room Temperature in Sm2+ Doped Substitutionally Disordered Microcrystals, |
22 MAY 1992 |
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| Authors:
R. Bilmers; J. Davis; M. Squicciarini; NAVAL AIR DEVELOPMENT CENTER WARMINSTER PA
|
| Filter operation is achieved by depleting the ground state population of molecules whose local environments are within the bandwidth of the hole-burning pump laser. Hole-burning is achieved in these systems via a mechanism known as triplet-trapping which is shown in Figure l. The first step in this mechanism is absorption from the ground singlet state, S sub 0, to the-first excited singlet state, S sub 1, in the dye molecule. ... |
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| The Role of Interfaces in Fiber-Reinforced Brittle Matrix Composites, |
1991 |
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| Authors:
A. G. Evans; F. W. Zok; J. Davis; CALIFORNIA UNIV SANTA BARBARA DEPT OF MATERIALS
|
| The dominant influence of fiber coatings on the mechanical performance of brittle matrix composites is discussed. These effects are described in terms of two independent mechanical parameters, the debond energy, and the sliding resistance along the debond. Complications associated with mode mixity, roughness and coating microstructure are emphasized. A mechanics of composite behavior based on these parameters is described, together with measurement approaches that allow the parameters to be evaluated ... |
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| Heavy Lift Helicopter Flight Control System. Volume III. Automatic Flight Control System Development and Feasibility Demonstration |
SEP 1977 |
706 pages |
| Authors:
J. Davis; T. Garnett; J. Gaul; BOEING VERTOL CO PHILADELPHIA PA
|
| The U.S. Army Heavy Lift Helicopter Advanced Technology Component program required the design, development, and feasibility demonstration of an electrohydraulic flight control system. This volume details the evolution of an automatic flight control system (AFCS), operating by means of a direct electrical linkage. AFCS software and hardware development and testing are discussed. The results of flight clearance testing and in-flight evaluations of AFCS control laws are examined. |
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Reports by Author
