656 Matching Results

Search Results

Advanced search parameters have been applied.

New Ways: Tiltrotor Aircraft and Magnetically Levitated Vehicles

Description: Common issues for these systems include their possible contributions to improving mobility in congested corridors, U.S. technology leadership, the Federal role in transportation research and development, and institutional and community barriers to major, new infrastructure programs. Moreover, some Federal financing is likely to be required if commercial maglev or tiltrotor technologies are to be developed by U.S. industry over the next decade. Congress will need to clarify its objectives for supporting or encouraging these technologies before it can make wise decisions on when or whether to undertake substantial, long-term Federal programs in support of either or both of them. This report identifies several funding and management options for consideration if such goals are established.
Date: September 1991
Creator: United States. Congress. Office of Technology Assessment.
Partner: UNT Libraries Government Documents Department

A Study of Some Biological Effects of Non-Ionizing Electromagnetic Radiation

Description: The experimental studies of this work were done using a microwave cavity spectrometer, Escherichia coli (E-coli) bacteria, and other peripheral equipment. The experiment consists of two steps. First, a general survey of frequencies from 8 GHz to 12 GHz was made. Second, a detailed experiment for specific frequencies selected from the first survey were further studied. Interesting frequency dependent results, such as unusually higher growing or killing rates of E-coli at some frequencies, were found. It is also concluded that some results are genetic, that is, the 2nd, and 3rd subcultures showed the same growing status as the 1st cultures.
Date: December 1996
Creator: Park, Young C. (Young Chul), 1960-
Partner: UNT Libraries

An Electro- Magneto-static Field for Confinement of Charged Particle Beams and Plasmas

Description: A system is presented that is capable of confining an ion beam or plasma within a region that is essentially free of applied fields. An Artificially Structured Boundary (ASB) produces a spatially periodic set of magnetic field cusps that provides charged particle confinement. Electrostatic plugging of the magnetic field cusps enhances confinement. An ASB that has a small spatial period, compared to the dimensions of a confined plasma, generates electro- magneto-static fields with a short range. An ASB-lined volume thus constructed creates an effectively field free region near its center. It is assumed that a non-neutral plasma confined within such a volume relaxes to a Maxwell-Boltzmann distribution. Space charge based confinement of a second species of charged particles is envisioned, where the second species is confined by the space charge of the first non-neutral plasma species. An electron plasma confined within an ASB-lined volume can potentially provide confinement of a positive ion beam or positive ion plasma. Experimental as well as computational results are presented in which a plasma or charged particle beam interact with the electro- magneto-static fields generated by an ASB. A theoretical model is analyzed and solved via self-consistent computational methods to determine the behavior and equilibrium conditions of a relaxed plasma. The equilibrium conditions of a relaxed two species plasma are also computed. In such a scenario, space charge based electrostatic confinement is predicted to occur where a second plasma species is confined by the space charge of the first plasma species. An experimental apparatus with cylindrical symmetry that has its interior surface lined with an ASB is presented. This system was developed by using a simulation of the electro- magneto-static fields present within the trap to guide mechanical design. The construction of the full experimental apparatus is discussed. Experimental results that show the characteristics of ...
Date: May 2014
Creator: Pacheco, Josè L.
Partner: UNT Libraries

Using the CAVE virtual-reality environment as an aid to 3-D electromagnetic field computation

Description: One of the major problems in three-dimensional (3-D) field computation is visualizing the resulting 3-D field distributions. A virtual-reality environment, such as the CAVE, (CAVE Automatic Virtual Environment) is helping to overcome this problem, thus making the results of computation more usable for designers and users of magnets and other electromagnetic devices. As a demonstration of the capabilities of the CAVE, the elliptical multipole wiggler (EMW), an insertion device being designed for the Advanced Photon Source (APS) now being commissioned at Argonne National Laboratory (ANL), wa made visible, along with its fields and beam orbits. Other uses of the CAVE in preprocessing and postprocessing computation for electromagnetic applications are also discussed.
Date: August 1995
Creator: Turner, L. R.; Levine, D.; Huang, M.; Papka, M & Kettunen, L.
Partner: UNT Libraries Government Documents Department

DSI3D-RCS: Theory manual

Description: The DSI3D-RCS code is designed to numerically evaluate radar cross sections on complex objects by solving Maxwell`s curl equations in the time-domain and in three space dimensions. The code has been designed to run on the new parallel processing computers as well as on conventional serial computers. The DSI3D-RCS code is unique for the following reasons: Allows the use of unstructured non-orthogonal grids, allows a variety of cell or element types, reduces to be the Finite Difference Time Domain (FDTD) method when orthogonal grids are used, preserves charge or divergence locally (and globally), is conditionally stable, is non-dissipative, is accurate for non-orthogonal grids. This method is derived using a Discrete Surface Integration (DSI) technique. As formulated, the DSI technique can be used with essentially arbitrary unstructured grids composed of convex polyhedral cells. This implementation of the DSI algorithm allows the use of unstructured grids that are composed of combinations of non-orthogonal hexahedrons, tetrahedrons, triangular prisms and pyramids. This algorithm reduces to the conventional FDTD method when applied on a structured orthogonal hexahedral grid.
Date: March 16, 1995
Creator: Madsen, N.; Steich, D.; Cook, G. & Eme, B.
Partner: UNT Libraries Government Documents Department

The NASA B-757 HIRF test series: Low power on-the-ground tests

Description: The data acquisition phase of a program intended to provide data for the validation of computational, analytical and experimental for the assessment of electromagnetic effects i n transports, for the checkout of instrumentation for following test programs, and for the support of protection engineering of airborne systems has been completed. Funded by the NASA Fly-By-Light/Power-By-Wire Program, the initial phase involved on-the-ground electromagnetic measurements using the NASA Boeing 757 and was executed in the LESLI Facility at the USAF Phillips Laboratory. The major participants were LLNL, NASA Langley Research Center, Phillips Laboratory, and UIE, Inc. Measurements were made of the fields coupled into the aircraft interior and signals induced in select structures and equipment under controlled illumination by RF fields. A characterization of the ground was also performed to permit ground effects to be included in forthcoming validation exercises. A series of fly-by experiments were conducted in early 1995 in which the NASA B-757 was flown in the vicinity of a Voice of America station ({approximately}25 MHz), a fixed transmitter driving an LP array (172 MHz), and an ASRF radar at Wallops Island (430 MHz). In this paper, the overall test program is defined with particular attention to the on-the-ground portion. It is described in detail with presentation of the test rationale, test layout, and samples of the data. Samples of some inferences from the data that will be useful in protection engineering and EM effects mitigation will also be presented.
Date: July 1, 1995
Creator: Poggio, A.J.; Zacharias, R.A.; Pennock, S.T.; Avalle, C.A. & Carney, H.
Partner: UNT Libraries Government Documents Department

3-D computer simulations of EM fields in the APS vacuum chamber: Part 1, Frequency-domain analysis

Description: The vacuum chamber proposed for the storage ring of the 7-GeV Advanced Photon Source (APS) basically consists of two parts: the beam chamber and the antechamber, connected to each other by a narrow gap. A sector of 1-meter-long chamber with dosed end plates, to which are attached the 1-inch-diameter beampipes centered at the beam chamber, has been built for experimental purposes. The 3-D code MAFIA has been used to simulate the frequency-domain behaviors of EM fields in this setup. The results are summarized in this note and are compared with that previously obtained from 2-D simulations and that from network analyzer measurements. They are in general agreement. A parallel analysis in the time-domain is reported in a separate note. The method of our simulations can be briefly described as follows. The 1-inch diameter beampipes are terminated by conducting walls at a length of 2 cm. The whole geometry can thus be considered as a cavity. The lowest RF modes of this geometry are computed using MAFIA. The eigenfrequencies of these modes are a direct output of the eigenvalue solver E3, whereas the type of each mode is determined by employing the postprocessor P3. The mesh sizes are chosen such that they are small enough for computations in the frequency region in which we are interested (the sampling theorem), while the total number of mesh points is still well within the range that our computer system can cope with.
Date: September 4, 1990
Creator: Chou, W. & Bridges, J.
Partner: UNT Libraries Government Documents Department

Electromagnetic mixed waste processing system for asbestos decontamination

Description: DOE sites contain a broad spectrum of asbestos materials (cloth, pipe lagging, sprayed insulation and other substances) which are contaminated with a combination of hazardous and radioactive wastes due to its use during the development of the U.S. nuclear weapons complex. These wastes consist of cutting oils, lubricants, solvents, PCB`s, heavy metals and radioactive contaminants. The radioactive contaminants are the activation, decay and fission products of DOE operations. The asbestos must be converted by removing and separating the hazardous and radioactive materials to prevent the formation of mixed wastes and to allow for both sanitary disposal and effective decontamination. Currently, no technology exists that can meet these sanitary and other objectives.
Date: December 1, 1995
Creator: Kasevich, R.S.; Vaux, W.G. & Nocito, T.
Partner: UNT Libraries Government Documents Department

Time efficient 3-D electromagnetic modeling on massively parallel computers

Description: A numerical modeling algorithm has been developed to simulate the electromagnetic response of a three dimensional earth to a dipole source for frequencies ranging from 100 to 100MHz. The numerical problem is formulated in terms of a frequency domain--modified vector Helmholtz equation for the scattered electric fields. The resulting differential equation is approximated using a staggered finite difference grid which results in a linear system of equations for which the matrix is sparse and complex symmetric. The system of equations is solved using a preconditioned quasi-minimum-residual method. Dirichlet boundary conditions are employed at the edges of the mesh by setting the tangential electric fields equal to zero. At frequencies less than 1MHz, normal grid stretching is employed to mitigate unwanted reflections off the grid boundaries. For frequencies greater than this, absorbing boundary conditions must be employed by making the stretching parameters of the modified vector Helmholtz equation complex which introduces loss at the boundaries. To allow for faster calculation of realistic models, the original serial version of the code has been modified to run on a massively parallel architecture. This modification involves three distinct tasks; (1) mapping the finite difference stencil to a processor stencil which allows for the necessary information to be exchanged between processors that contain adjacent nodes in the model, (2) determining the most efficient method to input the model which is accomplished by dividing the input into ``global`` and ``local`` data and then reading the two sets in differently, and (3) deciding how to output the data which is an inherently nonparallel process.
Date: August 1, 1995
Creator: Alumbaugh, D.L. & Newman, G.A.
Partner: UNT Libraries Government Documents Department

Draft environmental impact statement for construction and operation of the proposed Bangor Hydro-Electric Company`s second 345-kV transmission tie line to New Brunswick

Description: This Draft Environmental Impact Statement (DEIS) was prepared by the US Department of Energy (US DOE). The proposed action is the issuance of Presidential Permit PP-89 by DOE to Bangor Hydro-Electric Company to construct and operate a new international transmission line interconnection to New Brunswick, Canada that would consist of an 83.8 mile (US portion), 345-kilovolt (kV) alternating current transmission line from the US-Canadian border at Baileyville, Maine to an existing substation at Orrington, Maine. The principal environmental impacts of the construction and operation of the transmission line would be incremental in nature and would include the conversion of forested uplands (mostly commercial timberlands) and wetlands to right-of-way (small trees, shrubs, and herbaceous vegetation). The proposed line would also result in localized minor to moderate visual impacts and would contribute a minor incremental increase in the exposure of some individuals to electromagnetic fields. This DEIS documents the purpose and need for the proposed action, describes the proposed action and alternatives considered and provides a comparison of the proposed and alternatives routes, and provides detailed information on analyses of the environmental consequences of the proposed action and alternatives, as well as mitigative measures to minimize impacts.
Date: October 1, 1993
Partner: UNT Libraries Government Documents Department

Assessment of health impacts in electricity generation and use

Description: This paper describes the health effects of concern associated with electricity generation, information from which health effects can be estimated, and how the boundaries of analysis are determined. It also describes advances, new approaches, and trends in the risk assessment process. It discusses the application of these advances to comparative risk studies. Trends in the risk assessment process include more explicit characterization of quantitative uncertainty, the broader application and acceptance of Monte Carlo analysis and other numerical methods to the propagation of uncertainties through the analysis, greater realism in risk assessment, and the application of greatly increased computational capabilities.
Date: November 1, 1995
Creator: Morris, S.C.
Partner: UNT Libraries Government Documents Department

Kinetic Ballooning Instability as a Substorm Onset Mechanism

Description: A new scenario of substorm onset and current disruption and the corresponding physical processes are presented based on the AMPTE/CCE spacecraft observation and a kinetic ballooning instability theory. During the growth phase of substorms the plasma beta is larger than unity (20 greater than or equal to beta greater than or equal to 1). Toward the end of the late growth phase the plasma beta increases from 20 to greater than or equal to 50 in approximately 3 minutes and a low-frequency instability with a wave period of 50 - 75 sec is excited and grows exponentially to a large amplitude at the current disruption onset. At the onset, higher-frequency instabilities are excited so that the plasma and electromagnetic field form a turbulent state. Plasma transport takes place to modify the ambient pressure profile so that the ambient magnetic field recovers from a tail-like geometry to a dipole-like geometry. A kinetic ballooning instability (KBI) theory is proposed to explain the low-frequency instability (frequency and growth rate) and its observed high beta threshold (beta subscript c is greater than or equal to 50). Based on the ideal-MHD theory beta subscript c, superscript MHD approximately equals 1 and the ballooning modes are predicted to be unstable during the growth phase, which is inconsistent with observation that no appreciable magnetic field fluctuation is observed. The enhancement beta subscript c over beta subscript c, superscript MHD is due to the kinetic effects of trapped electrons and finite ion-Larmor radii which provide a large stabilizing effect by producing a large parallel electric field and hence a parallel current that greatly enhances the stabilizing effect of field line tension. As a result, beta subscript c is greatly increased over beta subscript c, superscript MHD by a factor proportional to the ratio of the total electron density ...
Date: October 1, 1999
Creator: C.Z.Cheng
Partner: UNT Libraries Government Documents Department

Generation of low-frequency electric and magnetic fields during large- scale chemical and nuclear explosions

Description: We discuss the main parameters of the electric field in the surface layer of the atmosphere and the results of the investigations of the natural electric field variations. Experimental investigations of the electromagnetic field for explosions in air are presented. Electromagnetic signals generated by underground nuclear and chemical explosions are discussed and explosions for 1976--1991 are listed. Long term anomalies of the earth`s electromagnetic field in the vicinity of underground explosions were also investigated. Study of the phenomenon of the irreversible shock magnetization showed that in the zone nearest to the explosion the quasistatic magnetic field decreases in inverse proportion to the distance.
Date: June 1, 1995
Creator: Adushkin, V.V.; Dubinya, V.A.; Karaseva, V.A.; Soloviev, S.P. & Surkov, V.V.
Partner: UNT Libraries Government Documents Department

A free-wave accelerator

Description: In recent years, radically new methods for accelerating charged particles to high energies have been proposed. These methods have ranged from various kinds of plasma wave accelerators to inverse free electron lasers. Recently, the Free Wave Accelerator (FWA) was proposed whereby a large net energy is imparted to electrons via the field of an extremely powerful laser whose intensity produces quiver energies significantly greater than the electron rest mass. The authors present one- and three-dimensional calculations of the motion of relativistic electrons under the influence of an intense, linearly polarized laser and a static magnetic field, where strong acceleration of electrons is obtained. The electron dynamics in the case of a focused laser beam are compared to that of a pure plane wave. The focused laser beam tends to eject the electron due to the strong transverse ponderomotive force. It is shown that by depressing the laser beam`s central intensity the electron will remain within the focus.
Date: March 31, 1995
Creator: Woodworth, J.G.; Kreisler, M.N. & Kerman, A.K.
Partner: UNT Libraries Government Documents Department

Effect of Sawtooth Oscillations on Energetic Ions

Description: The work summarizes results of the authors' studies on the energetic ion transport induced by sawtooth oscillations in tokamaks. The main attention is paid to description of physical mechanisms responsible for the transport. In addition to overview, the work contains new material. The new results concern the resonant interaction of the particles and the electromagnetic field of the sawtooth crash. In particular, it is discovered that the dominant harmonic of the crash (m = n = 1) can lead to stochastic motion of particles having large orbit width (potatoes). Regular motion of potatoes and quasi-stagnation particles in the presence of an n = 1 mode is studied, and their characteristic displacements associated with quick switching on/off the mode are found.
Date: December 10, 1999
Creator: White, R.B.; Lutsenko, V.V.; Kolesnichenko, Ya. I. & Yakovenko, Yu. V.
Partner: UNT Libraries Government Documents Department

Transverse multibunch modes for non-rigid bunches, including mode coupling

Description: A method for computing transverse multibunch growth rates and frequency shifts in rings, which has been described previously, is applied to the PEP-II B factory. The method allows multibunch modes with different internal-bunch oscillation modes to couple to one another, similar to single-bunch mode coupling. Including coupling between the multibunch modes gives effects similar to those seen in single-bunch mode coupling. These effects occur at currents that are lower than the single-bunch mode coupling threshold.
Date: August 1, 1995
Creator: Bert, J.S. & Ruth, R.D.
Partner: UNT Libraries Government Documents Department

Energy stability in recirculating, energy-recovering linacs

Description: Recirculating, energy-recovering linacs can be used as driver accelerators for high power FELs. Instabilities which arise from fluctuations of the cavity fields are investigated. Energy changes can cause beam loss on apertures, or, when coupled to M{sub 56}, phase oscillations. Both effects change the beam induced voltage in the cavities and can lead to unstable variations of the accelerating field. Stability analysis for small perturbations from equilibrium is performed and threshold currents are determined. Furthermore, the analytical model is extended to include amplitude and phase feedback, with the transfer function in the feedback path presently modeled as a low-pass filter. The feedback gain and bandwidth required for stability are calculated for the high power UV FEL proposed for construction at CEBAF. 4 refs.
Date: July 1, 1996
Creator: Merminga, L.; Bisognano, J.J. & Delayen, J.R.
Partner: UNT Libraries Government Documents Department

Dissemination and support of ARGUS for accelerator applications. Final report, April 24, 1991--April 14, 1995

Description: The effort has two broad goals, which have been prioritized by DOE, as follows: to enhance the ARGUS code for use in practical accelerator design simulations; to release ARGUS to the accelerator community through the Los Alamos Accelerator Code Group (LAACG). During the contract period, ARGUS versions 24 and 25 have been released. An upgraded version 25 (ARGUS v.25c) will be released in July, 1995, and will include all of the features that are tested and working at the conclusion of the DOE-funded effort. The effort that consolidated version 24 established a set of core capabilities that all ARGUS modules could access. Version 25 incorporated several major improvements: (1) a new frequency-domain module was incorporated into ARGUS that can handle degenerate modes, lossy materials, and periodic boundary conditions with sub-phase specification, and that can utilize the ARGUS data handling machinery for multiblock operation; (2) HDF output was implemented to allow ARGUS to send data to visualization tools; (3) a plasma chemistry capability was included in the steady-state PIC module to allow ionization, stripping, electron attachment, charge exchange, and other ion rate processes to occur within the PIC calculation; (4) new structure input options for figures of translation (extrusion) and figures of revolution were implemented. This ARGUS release is supported on all Cray platforms and on the IBM RS6000 Unix workstation platform. Version 25 was released in February 1994. The ARGUS dissemination and support activities have proceeded in parallel with code enhancement. On-line ARGUS support is available at NERSC through ARGUS man pages, and at the SAIC ftp node at mclapo.saic.com, through the SAIC MOSAIC home page, and through ARGUS bulletin boards maintained at SAIC and at NERSC.
Date: April 14, 1995
Creator: Kostas, C.; Krueger, W.A.; Mankofsky, A.; Mondelli, A.A. & Petillo, J.J.
Partner: UNT Libraries Government Documents Department