4,069 Matching Results

Search Results

Advanced search parameters have been applied.

Far field acceleration

Description: Far fields are propagating electromagnetic waves far from their source, boundary surfaces, and free charges. The general principles governing the acceleration of charged particles by far fields are reviewed. A survey of proposed field configurations is given. The two most important schemes, Inverse Cerenkov acceleration and Inverse free electron laser acceleration, are discussed in detail.
Date: July 1995
Creator: Fernow, R. C.
Partner: UNT Libraries Government Documents Department

Fiscal Year 1998 report theoretical studies of ground energy coupling

Description: A method for calculating the redistribution of resonance radiation in hot, dense plasmas is developed by extending the Frequency Fluctuation Model (FFM). This paper is devoted to a brief review of lineshape theory in the linear response approximation, and an introduction to the FFM approach to the modeling of lineshapes in plasmas. This discussion begins with a consideration of the spectral lines emitted by complex ions in plasmas. As is well known, the lineshape is determined by the time- dependent coupling of the ion with the plasma environment. This plasma-emitter interaction, leads to Stark broadening of the spectral lines, and traditionally has been considered in the approximation which treats the ef&@ of the electrons on the emitting ion in the impact limit while the ionic perturbation is� taken to be quasi-static. In this approximation, the time dependence of the perturbation has been eliminated, resulting in a spectral line shape that has purely homogeneous and inhomogeneous contributions and that is described by a simple sum of independent electron imp� act broadened static components. In order to clarify the concepts presented, examples of radiative redistribution functions for simple cases are presented. Included is an example of an X-ray laser pumped system which illustrates the capability of the mpdel to provide a sensitive method for the study of radiative transfer under plasma conditions of partial redistribution. That is, in cases where the strong mixing limit is not attained so that the mixing of the inhomogeneous spectral line components is not fast enough to produce a completely redistributed line.
Date: December 10, 1998
Creator: Klein, L.
Partner: UNT Libraries Government Documents Department

The Use Of Physics In Answering Metaphysical Questions

Description: This paper by Hoyt Edge comments on Janusz Slawinski's paper "Electromagnetic Radiation and the Afterlife" by looking at Slawinski's arguments from a logical and structural point of view. Edge points out the logical shortcomings of Slawinski's arguments, and criticizes Slawinski for making bold claims upon lacking evidence. Edge gives credit to Slawinski for continuing the conversation about the afterlife, however.
Date: Winter 1987
Creator: Edge, Hoyt
Partner: UNT Libraries

Comments on Slawinski's Paper

Description: This paper by Keith Harary addresses Janusz Slawinki's paper "Electromagnetic Radiation And The Afterlife." Harary expresses why he remains unconvinced by Slawinski's electromagnetic radiation argument.
Date: Winter 1987
Creator: Harary, Keith, Ph.D.
Partner: UNT Libraries

Comments On "Electromagnetic Radiation And The Afterlife"

Description: This paper by Evan Harris Walker comments on Janusz Slawinski's paper named "Electromagnetic Radiation and the Afterlife." It states the shortcomings of Slawinski's electromagnetic radiation argument by specifying a variety of points that run counter to the argument's physical possibility.
Date: Winter 1987
Creator: Walker, Evan Harris, Ph.D.
Partner: UNT Libraries

Dispersive wave processing: a model-based solution

Description: Wave propagation through various media represents a significant problem in many applications in acoustics and electromagnetics especially when the medium is dispersive. We post a general dispersive wave propagation model that could easily represent many classes of dispersive waves and proceed to develop a model-based processor employing this underlying structure. The general solution to the model-based dispersive wave estimation problem is developed using the Bayesian maximum a posteriori approach which leads to the nonlinear extended Kalman filter processor.
Date: October 1, 1996
Creator: Candy, J.V. & Chambers, D.C.
Partner: UNT Libraries Government Documents Department

Ferrite insertion at Recycler Flying Wire System

Description: Ferrite rods are installed inside the flying-wire cavity of the Recycler Ring and at entrance and exit beam pipes in order to absorb high-frequency electromagnetic waves excited by the beam. However, these rods may also deteriorate the vacuum pressure of the ring. An investigation is made to analyze the necessity of the ferrite rods at the entrance and exit beam pipes.
Date: February 27, 2004
Creator: Ng, K.Y.
Partner: UNT Libraries Government Documents Department

Remarks On Janusz Slawinski's Paper

Description: This paper by Michael Grosso analyzes points made by Janusz Slawinski in their paper "Electromagnetic Radiation and the Afterlife." It specifies that the author's hypothesis cannot be tested currently, and thus, it cannot be falsified. More research and data is needed, according to Grosso.
Date: Winter 1987
Creator: Gross, Michael
Partner: UNT Libraries

915-MHz Radar Wind Profiler (915RWP) Handbook

Description: The 915 MHz radar wind profiler/radio acoustic sounding system (RWP/RASS) measures wind profiles and backscattered signal strength between (nominally) 0.1 km and 5 km and virtual temperature profiles between 0.1 km and 2.5 km. It operates by transmitting electromagnetic energy into the atmosphere and measuring the strength and frequency of backscattered energy. Virtual temperatures are recovered by transmitting an acoustic signal vertically and measuring the electromagnetic energy scattered from the acoustic wavefront. Because the propagation speed of the acoustic wave is proportional to the square root of the virtual temperature of the air, the virtual temperature can be recovered by measuring the Doppler shift of the scattered electromagnetic wave.
Date: January 1, 2005
Creator: Coulter, R.
Partner: UNT Libraries Government Documents Department

Electromagnetic rotational actuation.

Description: There are many applications that need a meso-scale rotational actuator. These applications have been left by the wayside because of the lack of actuation at this scale. Sandia National Laboratories has many unique fabrication technologies that could be used to create an electromagnetic actuator at this scale. There are also many designs to be explored. In this internship exploration of the designs and fabrications technologies to find an inexpensive design that can be used for prototyping the electromagnetic rotational actuator.
Date: August 1, 2010
Creator: Hogan, Alexander Lee
Partner: UNT Libraries Government Documents Department

A coaxial ring-sidearm power extraction design

Description: We report a successful klystron power extraction design, in which a TEM coaxial mode is transmitted into TE10 mode of a WR90 rectangular waveguide at 11.42 GHz, with very little TEM reflection and almost vanishing asymmetric (TEM {r_arrow} TE11, or monopole to dipole) reflectance. Our coupler consists of a ring (disk) around the coaxial waveguide, and a coax-WR90 sidearm junction. The methods used in the design are numerical simulation, performed on the MAFIA3 T3 time- domain module and on the High Frequency Structure Simulator, and analytical treatment to guide the numerical runs. The demerit parameters (dipole reflectance and TEM reflection) can be reduced as much as desired (to zero in principle), the only limitation being computer run time and memory. Results are accurate to a few percent.
Date: January 1, 1996
Creator: Ben-Menahem, S. & Yu, D.
Partner: UNT Libraries Government Documents Department

Micropower impulse radar technology and applications

Description: The LLNL-developed Micropower Impulse Radar (MIR) technology has quickly gone from laboratory concept to embedded circuitry in numerous government and commercial systems in the last few years[l]. The main ideas behind MIR, invented by T. McEwan in the Laser Program, are the generation and detection systems for extremely low- power ultra-wideband pulses in the gigaHertz regime using low-cost components. These ideas, coupled with new antenna systems, timing and radio-frequency (RF) circuitry, computer interfaces, and signal processing, have provided the catalyst for a new generation of compact radar systems. Over the past several years we have concentrated on a number of applications of MIR which address a number of remote-sensing applications relevant to emerging programs in defense, transportation, medical, and environmental research. Some of the past commercial successes have been widely publicized [2] and are only now starting to become available for market. Over 30 patents have been filed and over 15 licenses have been signed on various aspects of the MIR technology. In addition, higher performance systems are under development for specific laboratory programs and government reimbursables. The MIR is an ultra- wideband, range-gated radar system that provides the enabling hardware technology used in the research areas mentioned above. It has numerous performance parameters that can be Selected by careful design to fit the requirements. We have improved the baseline, short- range, MIR system to demonstrate its effectiveness. The radar operates over the hand from approximately I to 4 GHz with pulse repetition frequencies up to 10 MHz. It provides a potential range resolution of I cm at ranges of greater than 20 m. We have developed a suite of algorithms for using MIR for image formation. These algorithms currently support Synthetic aperture and multistate array geometries. This baseline MIR radar imaging system has been used for several programmatic applications.
Date: April 15, 1998
Creator: Mast, J., LLNL
Partner: UNT Libraries Government Documents Department

A damped detuned structure for the next linear collider

Description: An X-band Damped Detuned Structure (DDS) for NLC has been fabricated as part of a collaboration between KEK and SLAC. The individual cells were diamond point machined and microwave tested at KEK. The cells were diffusion bonded at SLAC. The structure has been cold tested. The time dependence of the beam induced dipole wakefields have been measured with the SLC beam in the test station ASSET. The structure is designed so that the dipole modes have an approximately gaussian density distribution in the frequency domain. This gives an approximately gaussian decrease of the wakefields for short times (about 10 ns), which is produced by the interference among the 206 modes in the lowest dipole mode band of the 206 cell structure. Without damping, however, the wakefields then rise back to a level which is approximately equal to the expected incoherent level from the 206 modes. The damping is accomplished by means of 4 rectangular slots or manifolds (approximately 5 mm by 10 mm) equally spaced in azimuth around the structure and running the full length of the structure. These manifolds act as single mode rectangular waveguides for the lowest band dipole modes, but are cut off for the accelerating mode. The manifolds are coupled to every cell in the structure, except for 3 at each end, by means of radial slots. Each of the four manifolds will have the dipole mode frequencies traveling in both directions and so are terminated on both ends. The structure will be installed in the NLC Test Accelerator this fall.
Date: September 1, 1996
Creator: Miller, R.H.; Adolphsen, C. & Bane, K.L.
Partner: UNT Libraries Government Documents Department

{open_quotes}Heavy light bullets{close_quotes} in electron-positron plasma

Description: The nonlinear propagation of circularly polarized electromagnetic waves with relativistically strong amplitudes in an unmagnetized hot electron-positron plasma with a small fraction of ions is investigated. The possibility of finding localized solutions in such a plasma is explored. It is shown that these plasmas support the propagation of {open_quotes}heavy light bullets{close_quotes}; nondiffracting and nondispersive electromagnetic (EM) pulses with large density bunching.
Date: March 1, 1995
Creator: Berezhiani, V.I. & Mahajan, S.M.
Partner: UNT Libraries Government Documents Department

Changes in gene expression following EMF exposure

Description: Experiments were designed to examine the effects of electromagnetic field (EMF) exposure on specific gene expression, an effect that can be deleterious, beneficial, or neutral, depending on the long-term consequences; however, the proof of a reproducible, quantitative biological effect (such as change in gene expression) will lead to latter experiments aimed at determining the relative contribution of these changes to cellular consequences. Past work by ourselves and by others has shown that measures of gene expression are extremely sensitive indicators of the cellular and biological effects of ionizing radiation, with transcriptional changes being detected by exposure of cells to doses of {gamma}-rays as low as 0.01 cGy that have no pronounced cellular consequences. On the basis of this work, the authors hypothesized that measures of gene expression will be equally sensitive to EMF effects on cells.
Date: October 1, 1997
Creator: Woloschak, G.E.; Paunesku, T.; Chang-Liu, C.M.; Loberg, L.; Gauger, J. & McCormick, D.
Partner: UNT Libraries Government Documents Department

Survey of electric field shear driven by radio frequency waves in tokamak plasmas

Description: The stabilization of plasma turbulence by sheared poloidal rotation is thought to explain enhanced confinement in tokamak plasmas. One method proposed for controlling sheared flow is the use of externally driven radio-frequency (RF) waves. A number of calculations and some experiments have suggested that a modest amount of power in the ion cyclotron range of frequencies (ICRF) can drive the needed flows. Previous calculations have relied on incompressible fluid models which balance RF forces in the poloidal direction against neoclassical viscosity. But the incompressible assumption is not always valid, particularly for ion Bernstein waves (IBW). Also, since the IBW is a kinetic wave by nature, a fully consistent model should include kinetic effects. In this paper, RF driven flows are calculated from both compressible fluid and kinetic points of view.
Date: November 1, 1998
Creator: Jaeger, E.F.; Berry, L.A. & Batchelor, D.B.
Partner: UNT Libraries Government Documents Department

Generation of THz Radiation by Excitation of InAs with a Free Electron Laser

Description: Terahertz (THz) radiation is generated by exciting an un-doped InAs wafer with a femtosecond free-electron laser (FEL) at the Thomas Jefferson National Accelerator Facility. A microwatt level of THz radiation is detected from the unbiased InAs emitter when it is excited with the femtosecond FEL pulses operated at a wavelength of 1.06 {mu}-m and 10 W average power.
Date: January 1, 2001
Creator: Tani, Mashiko; Kono, Shunsuke; Gu, Ping; Sakai, Kiyomi; Usami, Mamoru; Shinn, Michelle D. et al.
Partner: UNT Libraries Government Documents Department

Quantum Bridge Fabrication Using Photolithography

Description: The need for high-speed performance electronics in computers integrated circuits and sensors, require the fabrication of low energy consumption diodes. Nano fabrication methods require new techniques and equipment. We are currently developing a procedure to fabricate a diode based on quantum-effects. The device will act like a traditional diode, but the nanometer scale will allow it to reach high speeds without over heating. This new diode will be on a nano-bridge so it can be attenuated by an electromagnetic wave. The goal is to obtain similar current vs voltage response as in a silicon diode.
Date: April 16, 2001
Creator: Quinones, R.
Partner: UNT Libraries Government Documents Department