| A Three-Dimensional Finite Difference Time Domain - Perfectly Matched Layer Algorithm Based on Piecewise-Linear Approximation for Linear Dispersive Media |
24 FEB 2000 |
22 pages |
| Authors:
S. J. Yakura; David Dietz; AIR FORCE RESEARCH LAB KIRTLAND AFB NMDIRECTED ENERGY DIRECTORATE
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 | Starting with the unsplit-field uniaxial Perfectly Matched Layer (PML) formulation, a second-order accurate Finite Difference Time Domain (FDTD) - PML algorithm is obtained using the piecewise-linear approximation. Use of the FDTD-PML algorithm results in the proper long time limit behavior where the electric field value decreases exponentially to zero inside a PML medium long after an electromagnetic pulse is incident on the PML medium. The behavior ... |
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| A Three-Dimensional Finite-Difference Time-Domain Formulation for Nonlinear Materials With the Frequency-Dependent Electronic Conductivity and Polarization |
20 DEC 1999 |
16 pages |
| Authors:
S. Joe Yakura; David Dietz; AIR FORCE RESEARCH LAB KIRTLAND AFB NMDIRECTED ENERGY DIRECTORATE
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| We present a three dimensional finite difference time domain (FDTD) algorithm that is used to evaluate the propagation of electromagnetic waves in conductive and dispersive materials that exhibit the frequency dependent electric conductivity and polarization. We consider a case where the electric conductivity has the linear property, specifically through the first order (linear) electric conductivity function, and the electric polarization has both linear and ... |
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| An Accurate Method for FD-TD Plane Wave Propagation for Wide Band Excitations |
14 DEC 1999 |
16 pages |
| Authors:
Jeff T. MacGillivray; David Dietz; AIR FORCE RESEARCH LAB KIRTLAND AFB NMDIRECTED ENERGY DIRECTORATE
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| An accurate and efficient technique is presented for propagating wide band plane waves in a three-dimensional (3-D) finite difference time domain (FD- TD) grid. Commonly, the incident pulse is created via a separate, one dimensional auxiliary field grid and then applied to the 3-D grid. Although this paper focuses on the separate field formalism, the method can be applied to the scattered field formalism as well. As ... |
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| A Stability Analysis of the Perfectly Matched Layer Method |
12 NOV 1999 |
16 pages |
| Authors:
S. J. Yakura; David Dietz; Andy Greenwood; Ernest Baca; AIR FORCE RESEARCH LAB KIRTLAND AFB NMDIRECTED ENERGY DIRECTORATE
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| We perform a detailed stability analysis based on the unsplit-field uniaxial perfectly matched layer (PML) formulation. Our finding shows that it is essential to have transverse field gradients present at all times to stabilize PML calculations. In the absence of transverse field gradients, the PML method becomes unstable with the axial field components growing linearly in time. |
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| Penetration of Microwaves Through Dispersive Concrete Using a Three- Dimensional Finite-Difference Time-Domain Code |
30 JUN 1999 |
27 pages |
| Authors:
S. J. Yakura; David Dietz; AIR FORCE RESEARCH LAB KIRTLAND AFB NMDIRECTED ENERGY DIRECTORATE
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| In this paper, we present a new formulation of a three-dimensional Finite-Difference Time-Domain (FDTD) algorithm that is applicable for studying the penetration of microwave pulses in conductive and dispersive materials, such as concrete. We investigate the effects of microwaves penetrating into conductive and dispersive concrete using the newly formulated algorithm incorporated into a three-dimensional FDTD code. Because of the dispersive properties of concrete, both conductivity and polarization terms are taken ... |
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| Self-Optimization in Simulation-Aided High Power Microwave Source Design |
28 FEB 97 |
22 pages |
| Authors:
M. J. Arman; James Havranek; David Dietz; PHILLIPS LAB KIRTLAND AFB NM
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| Computer-aided simulation techniques are essential in the design and development of new High Power Microwave sources. Using simulation codes to optimize a process is very slow, however, due to the iterative nature of the optimization, and the true optimal values are never found because the parameters are optimized one at a time instead of the simultaneous minimization process needed for multivariable systems. We have developed a new method that automatically ... |
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| Radiation Electrodynamics of the Photo-Electron Cloud Produced By an Arbitrary Photon Pulse Incident on a Planar Emitting Surface in Vacuum |
JUN 94 |
136 pages |
| Authors:
David Dietz; PHILLIPS LAB KIRTLAND AFB NM
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| The electromagnetic radiation field produced by the cloud of accelerating electrons induced at a planar photoelectron emitting surface in vacuum by a photon pulse of arbitrary time profile incident upon that surface is derived analytically in the nonrelativistic, small-spot-size regime. This derivation provides scaling relations for the radiated fields explicit in the pulse and surface parameters. Electron cloud dynamics are discussed and integral expressions for the electric and magnetic fields ... |
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| Analytical Solution of the Equations for a Coaxial Plasma Gun Operating in the Snowplow Mode. 1. Weak Coupling Limit |
JUN 87 |
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| Authors:
David Dietz; AIR FORCE WEAPONS LAB KIRTLAND AFB NM
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 | The analysis solution of the system of coupled ordinary differential equations which describes the time evolution of an ideal coaxial plasma gun operating in the snowplow mode is obtained in the weak coupling limit, i.e., when the gun is fully influenced by the driving (RLC) circuit but the circuit is negligibly influenced by the gun. Criteria are derived for the validity of this limit and numerical examples are presented. ... |
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