| Focused Ion Beam Milling Applied in Future Tunable-Wavelength Nano-LED's Fabrication |
07 Jan 2010 |
8 pages |
| Authors:
Chuan-Pu Liu; NATIONAL CHENG KUNG UNIV TAINAN (TAIWAN)
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 | This is a report on the development of a technique of self-masking lithography for making high aspect-ratio nanopillars by using a volume swelling phenomenon during beam-material interactions. |
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| Quartz Crystal Microbalance Based System for High-Sensitivity Differential Sputter Yield Measurements (Preprint) |
20-Aug-2009 |
17 pages |
| Authors:
B Rubin; J L Topper; A P Yalin; C C Farnell; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
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| We present a quartz crystal microbalance (QCM) based system for high sensitivity differential sputter yield measurements of different target materials due to ion bombardment. The differential sputter yields can be integrated to find total yields. Possible ion beam conditions include ion energies in the range of 30-350 eV and incidence angles of 0-70o from normal. A four-grid ion optics system is used to achieve a collimated ion beam at low ... |
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| Near-Infrared Collisional Radiative Model for Xe Plasma Electrostatic Thrusters: The Role of Metastable Atoms |
Aug-2009 |
10 pages |
| Authors:
Yu-Hui Chiu; Rajesh Srivastava; Rainer A Dressler; Oleg Zatsarinny; Klaus Bartschat; Lalita Sharma; AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE
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| Metastable Xe atoms play an important role in the collisional radiative processes of dense xenon plasmas, including those of electric thrusters for space vehicles. Recent measurements and calculations of electron-excitation processes out of the metastable state have allowed for the development of a collisional radiative model for Xe near-infrared (NIR) emissions based on the population of the metastable level through radiative transitions, and based on depopulation through electron-impact excitation. A ... |
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| The Next Generation Focusing Lenses for Proton Beam Writing |
28 Jul 2009 |
9 pages |
| Authors:
Jeroen A van Kan; A A Bettiol; T Osipowicz; M B Breese; F Watt; NATIONAL UNIV OF SINGAPORE DEPT OF PHYSICS
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| The principal investigator (PI) has designed a new system for proton beam writing (PBW). The key characteristics are an improvement of the system demagnification of up to 8 and 30 in x and y respectively compared to commercially available systems from Oxford Microbeams. The target chamber is under construction and the system is expected to be assembled in October 2009. The PI has shown initial test on PBW for Ni ... |
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| Coherent Structures and Chaos Control in High-Power Microwave and Charged-Particle Beam Devices |
31-Jan-2009 |
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| Authors:
Chiping Chen; MASSACHUSETTS INST OF TECH CAMBRIDGE
|
 | This report summarizes research results obtained under the auspices of Air Force Office of Scientific Research, Grant No. FA9550-06-1-0269. In particular, we conducted vigorous theoretical and computational investigations of coherent structures and chaos in a wide range of intense electron beam plasmas relevant to the development of high-power microwave and particle-beam devices for directed energy applications. The research accomplishments includes: a) development of a small-signal theory of magnetrons, b) discovery ... |
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| Faraday Accelerator With Radio-Frequency Assisted Discharge (FARAD): A New Electrodeless Concept for Plasma Propulsion |
Oct-2008 |
67 pages |
| Authors:
Edgar Choueiri; Kurt Pozin; Ashley Hallock; PRINCETON UNIV NJ ELECTRIC PROPULSION LAB
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| A new electrodeless accelerator concept that relies on an RF-assisted discharge, an applied magnetic field, and electromagnetic acceleration using an inductive coil is presented. The primary advantage of this concept is that a preionized plasma is employed to lower the initial voltage threshold which applies to the formation of an inductive current sheet in other pulsed inductive accelerator concepts. |
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| Gun Emittance of a Space Charge Limited Diode Due to Temperature Effects and Surface Roughness |
Apr-2008 |
3 pages |
| Authors:
Paul B Larsen; Antonsen; Thomas M Jr; Khanh T Nguyen; David K Abe; MARYLAND UNIV COLLEGE PARK
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| The emittance of a space charge limited diode is investigated under thermal emission and with a simple surface roughness model. |
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| Large-Signal Code TESLA: Current Status and Recent Development |
Apr-2008 |
3 pages |
| Authors:
Baruch Levush; Antonsen; Thomas M Jr; Khanh T Nguyen; David K Abe; Igor A Chernyavskiy; Alexander N Vlasov; Simon J Cooke; NAVAL RESEARCH LAB WASHINGTON DC
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| The optimization and design of new high-power, high-efficiency klystron amplifiers relies increasingly on effective nonlinear simulation tools. One such tool is the large-signal code TESLA, which was successfully applied for the modeling of single-beam and multiple-beam klystron devices at the Naval Research Laboratory and which is now used by number of U.S. companies. TESLA is a highly efficient fully electromagnetic two-dimensional code that solves self-consistently the electromagnetic field equations (including ... |
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| Stress Gradient Induced Strain Localization in Metals: High Resolution Strain Cross Sectioning via Synchrotron X-Ray Diffraction (POSTPRINT) |
Apr-2008 |
12 pages |
| Authors:
M Croft; R K Sadangi; V Shukla; J Skaritka; K Sadananda; M Lakshmipathy; M Shepard; R L Holtz; K Horvath; Z Zhong; N Jisrawi; T Tsakalakos; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
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| Strain localization in the presence of a stress gradient is a phenomenon common to many systems described by continuum mechanics. Variations of this complex phenomenon lead to interesting nonlinear effects in materials/engineering science as well as in other fields. Here, the synchrotron based energy dispersive x-ray diffraction (EDXRD) technique is used for high spatial resolution profiling of both compression and tension induced strain localization in important materials/engineering problems. Specifically, compression ... |
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| Collection Efficiencies of Various Airborne Spray Flux Samplers Used in Aerial Application Research |
Jan-2008 |
11 pages |
| Authors:
W C Hoffmann; Bradley K Fritz; AGRICULTURAL RESEARCH SERVICE COLLEGE STATION TX
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| A low air speed, spray dispersion tunnel was constructed and used to evaluate the collection efficiency of passive spray flux collectors. The dispersion tunnel utilizes an air-assisted nozzle to generate a spray cloud with a D(sub V0.5) of 18.5 (+/-0.4)micrometers at air speeds ranging from 0.4-4.0 m/s. A sampling protocol was developed to minimize spray flux and air speed variation effects while providing a check on theoretical collection efficiency calculations. ... |
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| Surface Plasmon Polariton Dependence on Metal Surface Morphology |
13 NOV 2007 |
39 pages |
| Authors:
Robert E. Peale; UNIVERSITY OF CENTRAL FLORIDA ORLANDO
|
| Generation and propagation of surface plasmons on nano-structured gold films was studied using optical and electron-beam techniques. Optical excitation of surface plasmons in Au-black films prepared by evaporation in moderate vacuum was observed. Initial indication of propagation of surface plasmons at visible-light frequencies over ~10 nm length scales was observed. A tunable terahertz detector based on two-dimensional plasmons in a semiconductor heterostructure was designed. These results have application to the ... |
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| Ion Velocity Measurements within the Acceleration Channel of a Low Power Hall Thruster (Preprint) |
21 AUG 2007 |
28 pages |
| Authors:
Jr. Hargus William A.; Michael P. Nakles; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
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| This work presents axial ion velocity measurements within the acceleration channel of the Busek Co. Inc. BHT-200 200 W laboratory Hall thruster derived from laser-induced fluorescence measurements of the 5d[4]7/2-6p[3]5/2 xenon ion excited state transition. Acceleration channel centerline ion velocities were measured for one nominal and six related cases. These six cases were chosen to be representative of small variations of the applied propellant flow, magnetic field, and discharge charge ... |
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| Studies into sub 100 nm Resists for Proton Beam Writing |
05 JUL 2007 |
7 pages |
| Authors:
Jeroen A. van Kan; Andrew A. Bettiol; Thomas Osipowicz; Frank Watt; NATIONAL UNIV OF SINGAPORE DEPT OF PHYSICS
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| Project AOARD 06-4004 has resulted in 5 scientific publications in the areas of resist investigation for proton beam writing, optimized proton beam focusing through new methods of detecting secondary electrons, and theoretical calculations that show the absence of proximity effects in proton beam writing. The project's Main achievement is a paper in "Nano Letters" in which HSQ is introduced as a superior resist for proton beam writing down to the ... |
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| Small-Qubit-Number Methods for Superconductive Quantum Computation |
30 JUN 2007 |
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| Authors:
Karl K. Berggren; Terry P. Orlando; MASSACHUSETTS INST OF TECH CAMBRIDGE
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| We have developed two experimental schemes that can be used to implement the Factorized Quantum Lattice-Gas Algorithm for the 1 D Diffusion Equation with Persistent-Current Qubits. One scheme involves biasing the PC Qubit at multiple flux bias points throughout the course of the algorithm. An implementation analogous to that done in Nuclear Magnetic Resonance Quantum Computing is also developed. Errors due to a few key approximations utilized and differences between ... |
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| Design of a Compact, Optically Guided, Pinched, Megawatt Class Free-Electron Laser |
08 JUN 2007 |
31 pages |
| Authors:
Phillip Sprangle; Joseph Penano; Bahman Hafizi; NAVAL RESEARCH LAB WASHINGTON DC
|
| A conceptual design for a compact megawatt class FEL operating within atmospheric transmission windows is presented. The proposed FEL consists of an optically guided, pinched amplifier configuration driven by an RF linac. The gain length, efficiency, electron pulse slippage and the distance between the wiggler and first relay mirror are determined for a megawatt class design. Of particular concern in the design is the overall length of the optical system, ... |
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| Hollow Cathode Produced Electron Beams for Plasma Generation: Cathode Operation in Gas Mixtures |
15 DEC 2006 |
20 pages |
| Authors:
Scott Walton; Darrin Leonhardt; Richard Fernsler; NAVAL RESEARCH LAB WASHINGTON DC
|
| Pulsed hollow cathode discharges, used to generate kilovolt electron beams for the production of plasmas, were studied in low pressure (50-70 mTorr) backgrounds of argon, oxygen, nitrogen, SF sub 6 and mixtures thereof. Cathode currents were measured as a function of cathode voltage, duty factor, and relative gas concentration. The cathode current was found to have a dependence on all variables, with the greatest impact being operating gas for all ... |
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| CW Atom Laser |
04 AUG 2006 |
10 pages |
| Authors:
G. Raithel; MICHIGAN UNIV ANN ARBOR
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| A continuous-wave (cw), phase- and amplitude-stable atom laser based on magnetic guiding, magnetic compression, and continuous distributed evaporative cooling has been pursued. The continuous operation of a cold atomic beam in a high-gradient (up to 2.7kG/cm) magnetic guide of 1.7m length has been demonstrated. An imaging method has been developed that allows in-situ measurements of atom temperatures and fluxes. The atomic beam in the high-gradient portion of the guide has ... |
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| A Study of Particle Collisions in Electric Propulsion Plasma Plumes |
12 JUL 2006 |
9 pages |
| Authors:
Randy L. Spicer; Joseph Wang; Lubos Breida; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
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| All numerical simulations have some inherent error associated with the results but minimizing the error may also maximize the processing time of the simulation. The particle collision model used for this paper is Monte Carlo Collisions. The results of the simulations were compared to a vacuum tank experiment conducted at the Air Force Research Laboratory. The results were compared for simulations with and without collisions using different neutral densities and ... |
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| Electron-Ion Beam Coupling Through Collective Interactions |
JUL 2006 |
11 pages |
| Authors:
Adrian Wheelock; David L. Cooke; Nikolaos A. Gatsonis; AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE
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| Neutralization of ion beams in electric propulsion applications is a well-known phenomenon. The physics behind the robust matching of both ion and electron currents and densities are not. With electric propulsion devices moving into micro and macro regimes with colloids, FEEPs, and thruster arrays, thruster-neutralizer interactions are under increasing scrutiny. It is shown that Coulomb collisions, which can act to match velocities through strong ion-electron collisions between particles with low ... |
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| Electra: Repetitively Pulsed 700 J, 100 ns Electron Beam Pumped KrF Laser |
May-2006 |
5 pages |
| Authors:
J D Sethian; J L Giuliani; M F Wolford; F Hegeler; M C Myers; M Friedman; P Burns; R Jaynes; NAVAL RESEARCH LAB WASHINGTON DC PLASMA PHYSICS DIV
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| This paper presents a brief overview of the Electra laser system and report on the most recent results. The laser system consists of an electron beam pumped main amplifier with an aperture of 30x30 cm2, an e-beam pumped 10x10 cm2 pre-amplifier, and a commercial discharge laser serving as the seed oscillator. The main amplifier, currently operated as an oscillator, has demonstrated single shot and rep-rate laser energies exceeding 700 J, ... |
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| Development of High-Power Microwave Sources Based on Induction Linear Accelerator |
30 APR 2006 |
19 pages |
| Authors:
Weihua Jiang; Anatoli Shlapakovski; Tsuneo Suzuki; NAGAOKA UNIV OF TECHNOLOGY (JAPAN) EXTREME ENERGY DENSITY RESEARCH INST
|
| Experimental and simulation studies of antenna-amplifier and relativistic magnetron are being carried out in Nagaoka University of Technology (Japan) and Nuclear Physics Institute (Russia), as an international collaboration. The objective of these studies is to carry out experimental demonstration of antenna-amplifier and to perform experimental and simulation studies of relativistic magnetron with transparent cathode. The new concept of hybrid antenna-amplifier has been studied by three-dimensional particle-in-cell simulation and by experiment ... |
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| Electron Attachment to POCl3: Measurement and Theoretical Analysis of Rate Constants and Branching Ratios as a Function of Gas Pressure and Temperature, Electron Temperature, and Electron Energy |
31 MAR 2006 |
10 pages |
| Authors:
Jane M. Van Doren; Jeffrey F. Friedman; Thomas M. Miller; A. A. Viggiano; S. Denifl; P. Scheier; T. D. Mark; J. Troe; AIR FORCE RESEARCH LAB HANSCOM AFB MA
|
| Two experimental techniques, electron swarm and electron beam, have been applied to the problem of electron attachment to POCl3, with results indicating a competition between dissociation of the resonant POCl3 state and collisional stabilization of the parent anion. In the electron beam experiment at zero electron energy, the fragment ion POCl2- is the dominant ion product of attachment (96%) under single-collision conditions. Small amounts (~2% each) of POCl3- and Cl ... |
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| Multichannel + or - 1.16 KV Arbitrary Waveform Generator for Driving Multistage Ferroelectric Laser-Beam-Deflector |
Jan-2006 |
70 pages |
| Authors:
Fikri Muhammad; DELAWARE UNIV NEWARK DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
|
| Ferroelectric laser-beam-deflector has become one of the favorite devices for laser beam steering because of its ability to steer a laser beam without moving parts, its relatively high frequency of operation, and its large deflection angle. Furthermore, using multiple stages of ferroelectric beam deflector, the maximum deflection angle can be increased dramatically. However, these attractive features come with the cost of high drive-voltage requirement. Additionally, a multistage beam deflector requires ... |
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| Patterning of Narrow Au Nanocluster Lines Using V2O5 Nanowire Masks and Ion-Beam Milling |
2006 |
10 pages |
| Authors:
M. G. Ancona; S. E. Kooi; W. Kruppa; A. W. Snow; E. E. Foos; L. J. Whitman; D. Park; L. Shirey; NAVAL RESEARCH LAB WASHINGTON DC
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| In recent years there has been considerable interest in metallic and semiconducting nanoclusters for a variety of reasons, not least of which is their potential for electronics and sensors. Although there are worthwhile applications of these clusters in devices at the micron scale, e.g., in chemical vapor sensing, the most intriguing possibilities arise when the numbers of clusters are reduced to a relative few and the inherent scalability associated with ... |
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| Synchrotron Based X-Ray Strain Mapping in Fatigued Materials Subjected to Overloading |
2006 |
11 pages |
| Authors:
Thomas Tsakalakos; Mark C. Croft; Z Zhong; R. Holtz; K. Sadananda; RUTGERS - THE STATE UNIV NEW BRUNSWICK NJ
|
| The application of high-resolution strain mapping in large engineering samples with both high-spatial and strain resolution is reviewed in this report using high- energy photons between 100 and 300 KeV on beam line X17B1 of Brookhaven National Laboratory. This was achieved by using Energy Dispersive X-ray Diffraction (EDXRD) methods and synchrotron radiation for the nondestructive measurement of residual stresses in engineering components. Examples of residual stresses profiles will be presented ... |
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| Coherent Ion Acceleration Using Beating Electrostatic Waves |
DEC 2005 |
53 pages |
| Authors:
Edgar Choueiri; Rostislav Spektor; PRINCETON UNIV NJ DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
|
| In this final technical report we document, in three chapters and an appendix, the results obtained under the 1-year continuation AFOSR contract (FA9550-05-1-0181; Start date: 03/15/05; End date: 12/31/05) to our AFOSR-sponsored study of a new ion acceleration mechanism using beating electrostatic waves. The first phase of the work (F49620-02-1-0009; State date: 08/31/2002; End date: 9/1/04) was documented in detail in a final report submitted to AFOSR on 1/24/05. In ... |
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| Liquid Crystal on Silicon Non-Mechanical Steering of a Laser Vibrometer System |
SEP 2005 |
84 pages |
| Authors:
Kevin S. Kuciapinski; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| This research examined the possibility of using a non-mechanical beam steering device to steer the beam of a coherent laser radar system. Non-mechanical beam steering devices offer many advantages in size, weight, power requirements, and steering speeds. Additionally, non-mechanical beam steering devices present the capabilities of splitting a single beam into multiple beams as well as beam forming and expanding. The coherent laser radar system used was a Laser Vibrometer ... |
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| High Temperature Coatings by Pulsed Electron Beam Ablation |
AUG 2005 |
44 pages |
| Authors:
Olivier Sudre; David B. Marshall; Sergio Lucato; ROCKWELL SCIENTIFIC CO THOUSAND OAKS CA
|
| The objective of this program was to investigate the deposition and properties of new high temperature coatings using pulsed-electron-beam ablation (PEBA) and to characterize the corrosion of those compounds in relevant environments. The PEBA technique has potential advantages for depositing compounds that are known to be difficult to deposit by conventional electron-beam evaporation. The use of ablation rather than melting and evaporation avoids changes in composition associated with differing evaporation ... |
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| DSMC Simulations in Support of the STS-107 Accident Investigation |
13 JUL 2005 |
7 pages |
| Authors:
Michael A. Gallis; SANDIA NATIONAL LABS ALBUQUERQUE NM
|
| Three-dimensional Direct Simulation Monte Carlo simulations of columbia Shuttle Orbiter flight STS--107 are presented. The aim of this work is to determine the aerodynamic and heating behavior of the Orbiter during aerobraking maneuvers and to provide piecewise integration of key scenario events to assess the plausibility of the candidate failure scenarios. The flight of the Orbiter is examined at two altitudes: 350 kft and 300 kft. The flow field around ... |
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| Reverse Ion Acceleration by Laser-Matter Interaction |
JUN 2005 |
18 pages |
| Authors:
Peter Messmer; Peter H. Stoltz; Chet Nieter; Jean-Luc Cambier; AIR FORCE RESEARCH LAB EDWARDS AFB CA
|
| OUTLINE: * Forward ion acceleration * Ion acceleration in reflecting geometry * Simulations with pre-ionized plasma * Simulations including ionization. |
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| Multifunctional Silicon Aluminum Oxynitride (SiAlON) Ceramic Coatings for High Temperature Applications |
30 MAY 2005 |
23 pages |
| Authors:
Robert J. Lad; MAINE UNIV AT ORONO LAB FOR SURFACE SCIENCE AND TECHNOLOGY
|
| This project has demonstrated how controlled synthesis of nanostructured SiAlON thin films with varying composition yields an outstanding class of wear resistant and oxidation resistant coatings. SiAlON thin films spanning the full range of O/N and Al/Si ratios were deposited by RF magnetron co-sputtering of Al and Si targets in Ar/O2/N2 mixtures onto bare sapphire and Pt coated sapphire substrates. The films are amorphous and very smooth when deposited at ... |
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| Ionospheric Modification at Twice the Electron Cyclotron Frequency |
01 APR 2005 |
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| Authors:
F. T. Djuth; T. R. Pedersen; E. A. Gerken; P. A. Bernhardt; C. A. Selcher; W. A. Bristow; M. J. Kosch; AIR FORCE RESEARCH LAB HANSCOM AFB MA
|
| In 2004, a new transmission band was added to the HAARP high- frequency ionospheric modification facility that encompasses the second electron cyclotron harmonic at altitudes between ^220 and 330 km. Initial observations indicate that greatly enhanced airglow occurs whenever the transmission frequency approximately matches the second electron cyclotron harmonic at the height of the upper hybrid resonance. This is the reverse of what happens at higher electron cyclotron harmonics. The ... |
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| A Mechanical Loading/Synchrotron X-Ray Diffraction System for In-Situ Determination of Lattice Strains |
MAR 2005 |
9 pages |
| Authors:
Matthew Miller; Paul Dawson; CORNELL UNIV ITHACA NY OFFICE OF SPONSORED PROGRAMS
|
| A mechanical testing/synchrotron x-ray diffraction system was fabricated in this DURIP grant. The key elements of the system are a high frequency uniaxial loading machine, a precision diffractometer support Unit and an x-ray shutter (chopper). The system will be employed within synchrotron experimental facilities to measure lattice strains during cyclic deformation experiments as a means to understand the evolution of crystal stresses. |
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| Electro-Optic Beam Steering Using Domain Engineered Lithium Tantalate |
MAR 2005 |
81 pages |
| Authors:
Daren J. Chauvin; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| The operation of a 14-channel five stage electro-optic beam steering device was studied. Beam deflection scanned from 0o to 10.1o was demonstrated. The maximum angle is within 0.3% of design. Many laser systems in operation today implement mechanical beam steering methods that are often expensive in terms of cost, weight and power. They are slow and subject to wear and vibration. A non-inertial beam scanning mechanism, such as one based ... |
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| Hybrid Antenna Amplifier: A Controllable High Power Microwave Source |
MAR 2005 |
47 pages |
| Authors:
Anatoli Shlapakovski; TOMSK POLYTECHNIC UNIV (RUSSIA) NUCLEAR PHYSICS INST
|
| This report results from a contract tasking Nuclear Physics Institute at Tomsk Polytechnic University as follows: The contractor will evaluate the concept of hybrid antenna-amplifiers, i.e., devices representing a combination of a surface wave antenna and a traveling wave tube. Theoretical investigations and numerical simulations (including particle-in-cell simulations and complex calculations using existing electromagnetic codes) as well as prototype experiments on electron beam transport (in the absence of the antenna ... |
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| Active Optical Tracking with Spatial Light Modulators |
MAR 2005 |
95 pages |
| Authors:
Steven Mawhorter; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| Two spatial light modulators are utilized for beam splitting, steering and tracking. Both linear and holographic phase screens are used in a demonstration of technology to allow real time tracking to communicate in a one-to-several type scenario. One SLM is used to apply a linear phase modulation to steer multiple beams onto a detector. The spots that are produced represent the targets as they move around the field of view ... |
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| A Survey of Atom Interferometer Beam-Combination Configurations and Beam Splitter Designs |
04 FEB 2005 |
23 pages |
| Authors:
Xiaolei Zhang; NAVAL RESEARCH LAB WASHINGTON DC
|
| This report summarizes the state of the art of atom-interferometry experiments, with an emphasis on the beam-splitting and beam-combination configurations, as well as on the different choices of beam splitter designs including both the successful and the unsuccessful ones. Analyses and discussions are given on the relative merits of the different types of configurations and designs in the context of the different types of potential applications. The possible causes of ... |
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| Timing of Increasing Electron Counts From Geosynchronous Orbit to Low Earth Orbit |
JAN 2005 |
100 pages |
| Authors:
Kirk M. Olson; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| Under certain conditions, high energy electron fluxes can increase over short periods of time in the outer radiation belt and diffuse to low altitudes. Sudden increases of high energy electron densities at low altitudes can drastically damage unsuspecting low-earth-orbit satelites. The progression of electron flux increases from a geosynchronous orbit to low-earth orbit during an electron event is somewhat unknown. If the beginning of electron flux increases at low-earth-orbits could ... |
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| Two-Dimensional Photonic Crystals for Near IR and Visible Optoelectronics Applications |
2005 |
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| Authors:
David McIlroy; IDAHO UNIV MOSCOW
|
| The focus of this project is to develop a process for constructing two-dimensional (2D) photonic crystals, which will be amenable to commercialization. Our approach has been to utilize nanochannel glass (NCG), which consists of a 2D hexagonal arrays of cylindrical voids that traverse the entire thickness of the glass. A 2D photonic can be realized with NCG if high index materials with good transmission properties can be introduced into the ... |
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| Investigation of Ion Beam Neutralization Processes With 2-D and 3-D PIC Simulations |
DEC 2004 |
10 pages |
| Authors:
Adrian Wheelock; David L. Cooke; Nicholas A. Gatsonis; AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE
|
| While it is common knowledge that ion beams are easily neutralized for both current and charge density using a variety of means, the precise process of neutralization remains unknown. With the increasing importance of electric propulsion, and in particular micropropulsion systems, this question is of significant importance. Additionally, it has bearing on thruster design, space instrument calibration, electrodynamic tethers, and ionospheric research. A review of the present state of knowledge ... |
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| Beam Steering by Lag Synchronization in Ultra-Wide Bandwidth, Chaotic Arrays |
DEC 2004 |
3 pages |
| Authors:
Ned J. Corron; Jonathan N. Blakely; Shawn D. Pethel; ARMY AVIATION AND MISSILE COMMAND REDSTONE ARSENAL AL MISSILE RESEARCH DEVELOPMENT AND ENGINEERING CENTER
|
| We introduce a new method for beam steering in ultra-wide bandwidth arrays. The approach avoids the need for tunable microwave delays by using lag synchronization in a linear array of locally coupled chaotic oscillators. Steering is controlled by tuning the natural frequency of the oscillators and is analytically equivalent to first order to using explicit delay elements. Using chaotic rf circuits oscillating at tilde20MHz, we show both lag and lead ... |
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| Coaxial Virtual Cathode Enhancement |
20 OCT 2004 |
9 pages |
| Authors:
M. Kristiansen; J. Mankowski; TEXAS TECH UNIV LUBBOCK DEPT OF ELECTRICAL ENGINEERING
|
| Traditionally, the radiated microwave frequency in a coaxial vircator is considered to be determined primarily by the virtual cathode oscillation frequency and the electron reflection frequency. In this paper, some experiments showing different results are reported. Particularly, the E-beam is observed to play an important role in the cavity formation. Some possible explanations, including a virtual cavity concept, are proposed. The cavity resonance effect on a coaxial virtual cathode oscillator ... |
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| The Rapid Evaluation of Mean Concentration Fields in Lagrangian Stochastic Modelling Using a Density Kernel Estimator |
OCT 2004 |
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| Authors:
Y. Shao; E. Yee; DEFENCE RESEARCH AND DEVELOPMENT SUFFIELD (ALBERTA)
|
| Lagrangian Stochastic (LS) particle models have proven to be a useful computational tool for the description and prediction of dispersion of pollutant releases in complex meteorological situations (e.g., space- and time-varying situations pertaining to complex flow and turbulence). However, simulating the emitted pollutant by following the trajectories of many "marked" fluid elements released from the source distribution brings up the difficulty of the correct estimation of the mean concentration of ... |
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| Coherent Ion Acceleration Using Beating Electrostatic Waves |
01 SEP 2004 |
58 pages |
| Authors:
Edgar Choueiri; PRINCETON UNIV NJ DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
|
| The results obtained from AFOSR-sponsored study on a new ion acceleration using beating electrostatic waves. Unlike previously known methods of energizing plasmas with electrostatic waves, and which accelerate only ions whose initial velocities are above a certain threshold (close to the waves velocity), the new mechanism can accelerate ions with arbitrarily small initial velocities. This results in significant improvements to the acceleration/heating efficiency (by as much as 45%) over previous ... |
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| Advanced Electrodeless Plasma Propulsion Concepts |
25 JUN 2004 |
36 pages |
| Authors:
Edgar Choueiri; PRINCETON UNIV NJ ELECTRIC PROPULSION LAB
|
| OUTLINE: I. FARAD: Faraday Accelerator with RF-assisted Discharge: * Basic concept * Advantages * Basic questions and approach * Results of Proof-of-concept experiment. II. Ion acceleration by Beating Electrostatic Waves: * Basic concept * Advantages * Basic challenges * Status of research. |
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| Scattering-Matrix Analysis of Linear Periodic Arrays of Short Electric Dipoles |
MAY 2004 |
58 pages |
| Authors:
Robert Shore; Arthur D. Yaghjian; AIR FORCE RESEARCH LAB HANSCOM AFB MA SENSORS DIRECTORATE
|
| The scattering-matrix analysis of linear periodic arrays of electric dipoles given in this report was suggested by the corresponding analysis performed by Yaghjian for linear periodic arrays of electro-acoustic monopole transducers. The extension to electromagnetic antennas reported here requires the use of the more complicated vector spherical wave functions instead of scalar spherical wave functions. However, no new concepts are needed for our treatment. A general vector spherical-wave source scattering-matrix ... |
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| Reactions of O(+) With C(n)H(2n+2), n=2-4: A Guided-Ion Beam Study |
15 APR 2004 |
10 pages |
| Authors:
D. J. Levandier; Y. Chiu; R. A. Dressler; AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE
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| We have measured absolute reaction cross sections for the interaction of 0+ with ethane, propane, and n-butane at collision energies in the range from near thermal to approximately 20 eV, using the guided-ion beam (GIB) technique. We have also measured product recoil velocity distributions using the GIB time- of-flight (TOF) technique for several product ions at a series of collision energies. The total cross sections for each alkane are in ... |
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| Antenna Beam Steering Concepts for High Power Applications |
MAR 2004 |
26 pages |
| Authors:
Clifton C. Courtney; Donald E. Voss; Tom McVeety; VOSS SCIENTIFIC LLC ALBUQUERQUE NM
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| There is considerable interest in antennas that are high power capable, platform conformal, and steerable. These attributes are often at odds with one another, but we will discuss approaches to mechanically steer the direction of the peak beam of a large-slot array antenna. Traditionally, the slot spacing determines the direction of the radiated main beam of the antenna, and beam steering is accomplished by varying the frequency. But HPM sources ... |
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| TST Reconfigurable Aperture RF MEMS for Antenna Applications |
FEB 2004 |
68 pages |
| Authors:
E. W. Jacobs; H. B. Simonds; M. W. Roberts; T. O. Jones III; D. W. Brock; SPACE AND NAVAL WARFARE SYSTEMS CENTER SAN DIEGO CA
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| This report documents the progress of the Tactical SIGINT Technology (TST) program in investigating radio-frequency (RF) microelectromechanical system (MEMS) pulsed RF performance, and application of these devices to signal intelligence (SIGINT) reconfigurable antennas. |
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| Active Vibration Control for Free Electron Lasers |
DEC 2003 |
103 pages |
| Authors:
Aaron M. Stetler; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF PHYSICS
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| This thesis is concerned with active control methods for stabilizing the mirror vibrations of free-electron laser weapons on ships so that the laser continues to deliver full power Alignment of the mirrors is critical for proper operation because the electron beam and optical mode must substantially overlap. The alignment is expected to be difficult to maintain in a shipboard environment A theory for controlling the vibrations of a single-degree-of-freedom system ... |
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Particle Accelerators
