| RF Metamaterials for Foliage Penetration (FOPEN) Application |
Feb 2013 |
75 pages |
| Authors:
Nelson Poon; LOCKHEED MARTIN AERONAUTICS CO PALMDALE CA
|
 | Foliage Penetration (FOPEN) radars are critical for detecting and identifying targets concealed by trees and forests. Typically, FOPEN transmits at high powers, making them difficult to design and operate at low frequencies where mismatches are possible. Low operating frequencies also result in large apertures that limit FOPEN systems to large platforms. Novel metamaterials have the potential to reduce the size of FOPEN antennas, but two persistent challenges remain. First, high ... |
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| Evaluation and Understanding of the Laser Oscillation Property in Waveguides |
14 Nov 2012 |
12 pages |
| Authors:
Tomosumi Kamimura; OSAKA INST OF TECHNOLOGY OHMIYA INFORMATION AND COMMUNICATION ENGINEERING
|
| Excellent beam quality is indispensable for industrial application of high power lasers. However, high-power laser oscillation produces temperature gradients and thermal lensing inside the laser gain media resulting in laser power breakdown. This report describes fabrication of waveguide structures using Nd:YAG and YAG ceramics and investigation of their laser oscillation properties. The ceramic laser gain media evaluated was fabricated using materials controlled at macro-, micro- and nano-levels, and bonded into ... |
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| Model for Ultrafast Carrier Scattering in Semiconductors |
14 Nov 2012 |
20 pages |
| Authors:
Danhong Huang; David Cardimona; AIR FORCE RESEARCH LAB KIRTLAND AFB NM SPACE VEHICLES DIRECTORATE
|
| One of the major products the AF is looking for is a lightweight, reconfigurable electro-optic sensor system. Towards that end, we are investigating the possibilities of incorporating a protection layer, an optical signal amplification layer, a detection layer, a solid-state cooling layer, and a readout electronics layer all monolithically integrated within a single pixel of a semiconductor focal plane array (for vast reductions in size and weight). When completed, the ... |
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| Physics of the Geospace Response to Powerful HF Radio Waves |
31 Oct 2012 |
5 pages |
| Authors:
Evgeny Mishin; AIR FORCE RESEARCH LAB KIRTLAND AFB NM SPACE VEHICLES DIRECTORATE
|
| This report describes the results of studies of the response of the Earth's space plasma to high-power HF radio waves from the High-frequency Active Auroral Research Program (HAARP) facility in Alaska under the 2010-2012 AFOSR task Physics of the Geospace Response to Powerful HF Radio Waves'. A first-principle model of a HF-created ionizing wave has been developed, quantitatively explaining the observed artificial plasma layers. The FLIP model has been adapted ... |
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| 0.15-micron Gallium Nitride (GaN) Microwave Integrated Circuit Designs Submitted to TriQuint Semiconductor for Fabrication |
Sep 2012 |
18 pages |
| Authors:
John Penn; ARMY RESEARCH LAB ADELPHI MD SENSORS AND ELECTRON DEVICES DIRECTORATE
|
| High-speed electronic circuits are needed for Army systems in communications, wireless sensors, imaging, and other systems. Gallium nitride (GaN) technology offers the highest power densities for radio frequency (RF) and wireless integrated circuits. Several GaN broadband high power efficient power amplifier designs for high frequency operation, such as satellite communications (SATCOM), were recently designed and submitted for fabrication using a proprietary 0.15-micrometer GaN process under development at TriQuint Semiconductor. These ... |
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| High Power Fiber Lasers |
02 Aug 2012 |
45 pages |
| Authors:
John Ballato; MARTIN RICHARDSON; Michael Bass; Bryce Samson; CLEMSON UNIV SC OFFICE OF SPONSORED PROGRAM
|
| This program focused on new materials and fiber designs towards the realization of 100+ kW class eye-safe fiber lasers based on the following guiding principles: large mode area, single mode, purity of polarization state, minimization of nonlinear effects, compatibility with all-fiber pumps, and high temperature buffer coatings. Over the duration of this program the most significant findings are discussed below in the following sections: 1. Gain guided index anti guided ... |
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| A High Power Solid State Circuit Breaker for Military Hybrid Electric Vehicle Applications |
Aug 2012 |
10 pages |
| Authors:
Bruce Pilvelait; Calman Gold; Mike Marcel; DRS TEST AND ENERGY MANAGEMENT INC HUNTSVILLE AL
|
| Military vehicle electrical power systems require quickly responding fault protection to prevent mission failure, vehicle damage, or personnel injury. The electromechanical contactors commonly used for HEV protection have slow response and limited cycle life, factors which could result in fuse activation and disabling of the vehicle, presenting a dangerous situation for the soldier. A protection technology not often considered is Solid State Circuit Breakers (SSCB), which have fast response and ... |
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| Electric Propulsion of a Different Class: The Challenges of Testing for MegaWatt Missions |
Aug 2012 |
14 pages |
| Authors:
Roland Florenz; Thomas M Liu; Alec D Gallimore; Hani Kamhawi; Daniel L Brown; Richard R Hofer; James E Polk; MICHIGAN UNIV ANN ARBOR
|
| Currently, there is great interest in the development of high-power electric propulsion (EP) devices that can be employed in missions requiring 100 kW levels of propulsive power. Of the candidates for such thrusters, the Nested-channel Hall thruster (NHT) has been shown to be particularly scalable to this mission requirement. To this end, the University of Michigan s Plasmadynamics and Electric Propulsion Laboratory (PEPL), in conjunction with both the Air Force ... |
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| Suppression of Stimulated Brillouin Scattering in Optical Fibers Using a Linearly Chirped Diode Laser |
02 Jul 2012 |
11 pages |
| Authors:
J O White; A Vasilyev; J P Cahill; N Satyan; O Okusaga; G Rakuljic; C E Mungan; A Yariv; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The output of high power fiber amplifiers is typically limited by stimulated Brillouin scattering (SBS). An analysis of SBS with a chirped pump laser indicates that a chirp of 2.5 x 10 to the 15th power Hz/s could raise, by an order of magnitude, the SBS threshold of a 20-m fiber. A diode laser with a constant output power and a linear chirp of 5 x 10 to the 15th ... |
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| Electrochemical Energy Storage Materials |
Jul 2012 |
40 pages |
| Authors:
Michael F Durstock; Benji Maruyama; Patrick S Carlin; Gyanaranjan Pattanaik; Jacob M Haag; Daylond Hooper; Gordon Sargent; Placidus Amama; Neal A Pierce; Rahul Rao; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
|
| The objective of the Electrochemical Energy Storage program is to develop enabling materials systems for future electrochemical energy storage devices. The program focuses on developing nanostructured electrodes and improved solid state electrolytes for high power & energy density devices and to explore new 3D nanostructured architectures to enable optimal performance. The goal is to supply performance improvement (i.e. increased power and energy density, longer shelf and use life, and higher ... |
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| Next Generation Large Mode Area Fiber Technologies for High Power Fiber Laser Arrays |
08 Jun 2012 |
77 pages |
| Authors:
Almantas Galvanauskas; H Winful; Peter Dragic; E Honea; Stefan Heinemann; B Samson; MICHIGAN UNIV ANN ARBOR
|
| This program has successfully accomplished its main objective in that large core single-mode Ge-doped and Yb-doped CCC fibers have been developed as a platform for monolithically-integrated building blocks (individual laser channels) of high power beam-combined fiber laser arrays. Robust single-mode performance of CCC fibers with core sizes of up to 60m has been rigorously demonstrated. Various CCC fiber based high power lasers have been also demonstrated, including 600W SBS-free single-frequency ... |
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| CAM-7/LTO Cells for Lithium-Ion Batteries with Rapid Charging Capability at Low Temperature |
06 Apr 2012 |
5 pages |
| Authors:
David Ofer; Leah Nation; Sharon Dalton-Castor; Brian Barnett; Suresh Sriramulu; TIAX LLC LEXINGTON MA
|
| TIAX is developing laminated prismatic lithium-ion (Li-ion) cells capable of rapid charging at low temperature (to -50 deg C) to replace current lead-acid vehicle batteries. The novel cells are based on TIAX?s high energy, high power CAM-7 cathode material, high rate capability lithium titanate (LTO) anode material, and a nitrile-cosolvent electrolyte formulation, and target cell-level energy content greater than 90 Wh/kg and 250 Wh/l. |
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| Protection of Electronic Systems from the Effects of High-Power Microwave (HPM) and Ultra-Wideband (UWB) Sources |
24 Mar 2012 |
45 pages |
| Authors:
John Rodgers; Edo Waks; MARYLAND UNIV COLLEGE PARK INST FOR RESEARCH IN ELECTRONICS AND APPLIED PHYSICS
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| This grant to studied and developed innovative methods of hardening electronic systems against the effects of high power microwave (HPM) radiation. |
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| High Power Electrochemical Capacitors |
23 Mar 2012 |
14 pages |
| Authors:
Gleb Yushin; GEORGIA INST OF TECH ATLANTA SCHOOL OF MATERIALS SCIENCE AND ENGINEERING
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| Electrochemical supercapacitors are rechargeable electrochemical energy storage devices similar to batteries, but with different performance characteristics. Supercapacitors can store more power in a smaller volume and often at a lower cost. In contrast to batteries, supercapacitors have incredibly long cycle life ( 1000,000 cycles), and could be charged in less than a second. Their unique characteristics allow them to complement batteries in applications where high power and low weight are ... |
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| An Octave Bandwidth, High PAE, Linear, Class J GaN High Power Amplifier |
12 Mar 2012 |
6 pages |
| Authors:
Kris Skowronski; Steve Nelson; Rajesh Mongia; Howard Sheehan; Sid Anderson; COBHAM RICHARDSON TX SENSOR SYSTEMS
|
| In this paper, the design and measured performance of a wideband (1.2-2.5 GHz), high efficiency, high linearity, Gallium Nitride (GaN), Class J, 200-W power amplifier (PA) is reported. The Class J PA output stages exhibit 45-62% power-added efficiency (PAE) and a near-maximum power match over 2:1 bandwidth, and impressive 802.11g WLAN linearity. This linear PA has 65 to 70-dB small-signal gain over this bandwidth. |
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| Plasma and Electro-energetic Physics |
07 Mar 2012 |
26 pages |
| Authors:
John W Luginsland; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH
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| High Power Quantum Cascade Laser for Terahertz Imaging |
Mar 2012 |
69 pages |
| Authors:
Mun W Ng; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| Video rate or real-time imaging in the terahertz (THz) frequency range has become possible in the last few years with the advent of compact and high power THz sources, such as quantum cascade (QC) lasers, and the THz-sensitive vanadium oxide based microbolometer focal plane arrays. A new higher power QCL had been acquired and was characterized using FTIR spectroscopic techniques as part of this thesis. Spectral analysis revealed the center ... |
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| Nonlinear Frequency Conversion in III-V Semiconductor Photonic Crystals |
Mar 2012 |
160 pages |
| Authors:
Kelley Rivoire; STANFORD UNIV CA EDWARD L GINZTON LAB OF PHYSICS
|
| Nonlinear optical processes provide a physical mechanism for converting the frequency of light. This allows the generation of tunable light sources at wavelengths inaccessible with lasers, leading to a diverse set of applications in fields such as spectroscopy sensing, and metrology. To make these processes efficient has conventionally required relatively exotic materials that are incompatible with state of the art nanofabrication resulting in large-area devices that operate at high optical ... |
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| Fundamentals of Metamaterials for High-power RF Applications |
08 Feb 2012 |
11 pages |
| Authors:
Rebecca Seviour; Elena Luchinski; Yap S Tan; LANCASTER UNIV (UNITED KINGDOM) DEPT OF PHYSICS
|
| Microwave metamaterials have shown promise in numerous low power applications, ranging from strip lines to antennas. In general, metamaterials allow microwave designers to obtain electromagnetic characteristics not typically available in nature, leading to new behavior as well as reductions in the size of typical devices. High Power Microwave (HPM) sources have in the past drawn inspiration from work done in the conventional microwave source community. This programme of research focused ... |
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| Characterization of the Morphology of RDX Particles Formed by Laser Ablation |
Feb 2012 |
28 pages |
| Authors:
Jennifer L Gottfried; Jr De Lucia Frank C; Stephanie M Piraino; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| The morphology of cyclotrimethylenetrinitramine (RDX) particles produced by laser ablation has been characterized using scanning electron microscopy and Scanning Mobility Particle Sizer analyses. The effects of laser pulse energy, wavelength, and duration have been studied. Higher laser pulse energies resulted in higher concentrations of ablated RDX particles. Ultraviolet laser radiation is absorbed by RDX and results in the formation of agglomerated particles. Nano-RDX (mean particle size = 64 nm) was ... |
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| 11.72-sq cm Active-Area Wafer Interconnected PiN Diode Pulsed at 64 kA Dissipates 382 J and Exhibits an Action of 1.7 MA(sup 2)-s |
30 Jan 2012 |
5 pages |
| Authors:
M Snook; H Hearne; Ty McNutt; N El-Hinnawy; V Veliadis; B Nechay; S Woodruff; R S Howell; David Giorgi; Joe White; NORTHROP GRUMMAN SYSTEMS CORP LINTHICUM MD ELECTRONIC SYSTEMS
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| The Silicon carbide (SiC) device area is presently limited by material and processing defects. To meet the large current handling requirements of modern power conditioning systems, the paralleling of a large number of devices is required. This can increase costs and complexity through wafer dicing, device soldering, the inclusion of ballast resistors, and the formation of multiple wire bonds. Furthermore, paralleling numerous discrete devices increases package volume and weight and ... |
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| Leading Edge. Volume 7, Issue 4 |
Jan 2012 |
103 pages |
| Authors:
NAVAL SURFACE WARFARE CENTER DAHLGREN DIV VA
|
| The Leading Edge magazine is produced by the Naval Surface Warfare Center, Dahlgren, Virginia. The purpose of the publication is to showcase technical excellence across the Warfare Centers and promote a broader awareness of the breadth and depth of knowledge and support available to the Navy and DoD. Topics discussed are: directed energy weapons, acquisition, warfare management, technology, modeling and assessment, microwaves, high power, high energy lasers, and nonlethal capabilities. ... |
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| Leading Edge. Volume 7, Issue Number 4, 2012 |
Jan 2012 |
103 pages |
| Authors:
NAVAL SURFACE WARFARE CENTER DAHLGREN DIV VA
|
| The Leading Edge magazine is produced by the Naval Surface Warfare Center, Dahlgren, Virginia. The purpose of the publication is to showcase technical excellence across the Warfare Centers and promote a broader awareness of the breadth and depth of knowledge and support available to the Navy and DoD. In this issue of The Leading Edge magazine, you will trace the rich history of directed-energy work at Dahlgren, gain insight into ... |
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| Gallium Nitride (GaN) High Power Electronics (FY11) |
Jan 2012 |
36 pages |
| Authors:
Kenneth A Jones; Randy P Tompkins; Michael A Derenge; Kevin W Kirchner; Iskander G Batyrev; Shuai Zhou; ARMY RESEARCH LAB ADELPHI MD SENSORS AND ELECTRON DEVICES DIRECTORATE
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| This report covers work done for the Director's Research Initiative (DSI) on Gallium Nitride (GaN) High Power Electronics (HPE) in which GaN devices are assessed in comparison to those fabricated from silicon carbide (SiC). We show that for low power applications (less than 1500 V) GaN diodes should have a lower on-resistance, and therefore less loss, than their SiC counterparts because the critical breakdown field and electron mobility are larger. ... |
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| The Basics of Electric Weapons and Pulsed-Power Technologies |
Jan 2012 |
9 pages |
| Authors:
Stuart Moran; NAVAL SURFACE WARFARE CENTER DAHLGREN DIV VA
|
| Most conventional weapons rely on chemical energy (explosives) as their destruction mechanism, either to explode on target, like bombs, or to create kinetic energy, like a bullet. Electric weapons are different. Electric weapons use stored electrical energy, rather than explosives, to attack or destroy the target. Electric weapons generally fall into two categories: directed-energy weapons (DEWs) and electromagnetic (EM) launchers. DEWs send energy, instead of matter, toward a target, and ... |
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| A Fundamental Key to Next-Generation Directed-Energy Systems |
Jan 2012 |
7 pages |
| Authors:
NAVAL SURFACE WARFARE CENTER DAHLGREN DIV VA
|
| Naval Surface Warfare Center, Dahlgren Division (NSWCDD), is meeting the demanding requirements of next-generation Directed-Energy (DE) systems with Class-E radiofrequency (RF) transmitter switch-mode amplifiers designed to operate at ultrahigh efficiency, greater than 90 percent. Having discovered the key to next-generation DE systems, researchers at NSWCDD are focusing on the urgent need to counter-improvised explosive device (IED) systems with small, lightweight, highly efficient transmitters that use switch-mode amplifiers. Considering the multiplicity ... |
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| Directed Energy Using High-Power Microwave Technology |
Jan 2012 |
5 pages |
| Authors:
Jacob Walker; Matthew McQuage; NAVAL SURFACE WARFARE CENTER DAHLGREN DIV VA
|
| The Directed Energy Warfare Office (DEWO) and Directed Energy Division at the Naval Surface Warfare Center, Dahlgren Division (NSWCDD), merge past research and data with continuous innovation in the field of high-power microwave(s) (HPM) to address the critical need for nonlethal, nonkinetic weapons. HPM weapons can be described as nonkinetic devices that radiate electromagnetic energy in the radio frequency (RF) or microwave spectrum. They are designed to disrupt, deny, degrade, ... |
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| Naval Directed-Energy Weapons - No Longer a Future Weapon Concept |
Jan 2012 |
7 pages |
| Authors:
David C Stoudt; NAVAL SURFACE WARFARE CENTER DAHLGREN DIV VA
|
| Directed-energy weapon (DEW) technologies typically take the form of high- energy lasers (HELs), high-power microwaves (HPMs), and charged-particle beams. This article focuses on the first two technology areas, as they have reached the point of being ready for operational testing and evaluation, and in some cases, operational use on the battlefield. DEWs have been popularized in science-fiction writings for over a hundred years. The Department of Defense (DoD) has been ... |
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| Multifrequency Radio-Frequency (RF) Vehicle Stopper |
Jan 2012 |
7 pages |
| Authors:
Stephen A Merryman; NAVAL SURFACE WARFARE CENTER DAHLGREN DIV VA
|
| The widespread use of vehicle-borne improvised explosive devices (VBIEDs) in Iraq and Afghanistan has resulted in large numbers of military and civilian personnel being killed or injured. Consequently, the Joint Non-Lethal Weapons Directorate's (JNLWD) top priority is to identify, investigate, and develop technologies and capabilities to nonlethally stop both vehicles and vessels outside of minimum keep-out ranges (i.e., ranges where the rules of engagement would dictate the use of lethal ... |
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| High-Power Electrical Vehicle-Stopping Systems |
Jan 2012 |
5 pages |
| Authors:
Jordan Chaparro; Melanie Everton; NAVAL SURFACE WARFARE CENTER DAHLGREN DIV VA
|
| The military needs devices that can safely and reliably stop or arrest vehicles. The primary concern is security at entry control points and vehicle check points. In such scenarios, it is desirable to be able to stop unauthorized vehicles at predefined standoff ranges to protect personnel, equipment, and critical infrastructure. Both the military and civilian law enforcement agencies face similar issues with chase scenarios, where concerns over bringing an offending ... |
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| Nonlethal Small-Vessel Stopping with High-Power Microwave Technology |
Jan 2012 |
5 pages |
| Authors:
Jacob Walker; NAVAL SURFACE WARFARE CENTER DAHLGREN DIV VA
|
| The employment of small vessels to attack merchant ships and other seafaring units has emerged as a significant threat to international navigation and safe operations on the high seas. Along with swarm tactics, small vessels have been known to carry improvised explosive devices, help smuggle terrorists and weapons, and serve as attack platforms on the water for larger weapons. While kinetic solutions serve as the decisive option, alternative solutions that ... |
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| Historical Overview of Directed-Energy Work at Dahlgren |
Jan 2012 |
15 pages |
| Authors:
Stuart Moran; NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD
|
| In 1962, the United States set off a megaton nuclear weapon 250 miles above the Pacific. The blast caused a large imbalance of electrons in the upper atmosphere that interacted with the Earth's magnetic field to create oscillating electric fields over a large area of the Pacific. These fields were strong enough to damage electronics in Hawaii, a thousand miles away, and clearly demonstrated the effects of an electromagnetic pulse ... |
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| Control of Current and Voltage Oscillations in a Short dc Discharge Making Use of External Auxiliary Electrode |
Jan 2012 |
5 pages |
| Authors:
A S Mustafaev; V I Demidov; I Kaganovich; S F Adams; M E Koepke; A Grabovskiy; WEST VIRGINIA UNIV MORGANTOWN
|
| A dc discharge with a hot cathode is subject to current and voltage plasma oscillations, which have deleterious effects on its operation. The oscillations can be inhibited by installing an auxiliary electrode, placed outside of anode. By collecting a modest current through a small opening in anode, we show that the discharge becomes stable, in a certain pressure range. This method of avoiding current oscillations can be used, for example, ... |
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| BCN Graphene as Efficient Metal-Free Electrocatalyst for the Oxygen Reduction Reaction |
Jan 2012 |
5 pages |
| Authors:
Shuangyin Wang; Lipeng Zhang; Zhenhai Xia; Ajit Roy; Dong W Chang; Jong-Beom Baek; Liming Dai; ULSAN NATIONAL INSTITUTE OF SCIENCE AND TECHNOLOGY (KOREA SOUTH)
|
| The cathodic oxygen reduction reaction (ORR) is an important process in fuel cells and metal air batteries.[1 3] Although Pt-based electrocatalysts have been commonly used in commercial fuel cells owing to their relatively low overpotential and high current density, they still suffer from serious intermediate tolerance, anode crossover, sluggish kinetics, and poor stability in an electrochemical environment. This, together with the high cost of Pt and its limited nature reserves, ... |
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| Fundamental Studies of Electronic Properties of Materials and Devices for High Power, Compact Terahertz Vacuum Electron Devices |
23 Dec 2011 |
6 pages |
| Authors:
John H Booske; WISCONSIN UNIV MADISON
|
| The results of this investigation have yielded two major new research capabilities and several important advances in physical understanding of materials and devices at high (THz-regime) frequencies. A quasi-optical cavity THz measurement system was developed with a record-high Q and resolution capable of measuring differences in surface conductivity less than 10% at frequencies between 300- 1000 GHz. A multi physics computational model (EMC, FDTD, MD) was developed for electron transport ... |
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| Supplemental Task-High Power Lasers |
20 Dec 2011 |
15 pages |
| Authors:
Luke Lester; Ganesh Balakrisnan; NEW MEXICO UNIV ALBUQUERQUE CENTER FOR HIGH TECHNOLOGY MATERIALS
|
| The researchers made significant progress in all of the proposed research areas. The first task involved the growth and characterization of 1040 nm vertical external cavity surface emitting lasers (VECSELs). These devices have been grown by MOCVD and have been subjected to temperature-dependent reflectivity studies to optimize the alignment of the gain peak with the micro-cavity as well as examining their continuous wave output power properties. Secondly, based on extensive ... |
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| Reliability-Limiting Defects in GaN/AlGaN High Electron Mobility Transistors |
Dec 2011 |
112 pages |
| Authors:
Tania Roy; VANDERBILT UNIV NASHVILLE TN DEPT OF ELECTRICAL ENGINEERING
|
| GaN-based high electron mobility transistors (HEMTs) have gained popularity in high- frequency, high-power electronics owing to the high breakdown voltage and high mobility of GaN. The reliability of GaN-based devices is still an issue, and a lot of research is under way in order to bring GaN to parity with SiC in high-power application areas. In this work, we study the various reliability issues of GaN/AlGaN HEMTs that were fabricated ... |
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| Shielding Requirements for an Energy-Recovery Linac Free Electron Laser |
Dec 2011 |
109 pages |
| Authors:
Robert E Peterson; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| Many Free Electron Lasers (FELs) utilize high current, high energy electron beams. Inevitably, a small fraction of the electrons in the beam will exist outside the core beam; these electrons are referred to as beam halo. The halo electrons will travel down an FEL's transport system with the core electrons; any portion of those halo electrons that intercept transport system components can generate radiation that is harmful to the operating ... |
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| Beam Combining and Atmospheric Propagation of High Power Lasers |
09 Nov 2011 |
16 pages |
| Authors:
Phillip Sprangle; Joseph Penano; Bahman Hafizi; NAVAL RESEARCH LAB WASHINGTON DC BEAM PHYSICS BRANCH
|
| Solid state lasers are one of the candidates for efficient and compact directed energy systems. To achieve the necessary power levels many laser beams must be combined to form a single focused beam. We discuss coherent and incoherent combining of multi-kW, high quality lasers and the effects of atmospheric turbulence and aerosols on the propagation of the combined beams. We analyze the beam centroid wander and spreading contributions to the ... |
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| Carbon-Coated Current Collectors for High-Power Lithium-Ion Secondary Batteries |
20 Sep 2011 |
10 pages |
| Authors:
Nae-Lih Wu; NATIONAL TAIWAN UNIV TAIPEI DEPT OF CHEMICAL ENGINEERING
|
| The goal of this project is to develop a viable C-coating process of the current collector in order to improve the overall power performance of the electrode of Li-ion batteries. Two major parts of research works toward this goal were carried out. (1) Al and Cu foils were subjected to high-temperature chemical vapor deposition (T-CVD) to produce surface C-coating, and the resulting foils were used as current collectors for LiFePO4 ... |
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| Implementing Digital Feedback Controls for the Multiple Simultaneous Ring Cavities in the FASOR-X System |
Sep 2011 |
9 pages |
| Authors:
Jeffrey T Baker; David Gallant; Arthur Lucero; Harold Miller; Jonathon Stohs; AIR FORCE RESEARCH LAB KIRTLAND AFB NM SPACE VEHICLES DIRECTORATE
|
| Precision tuned high power (50W) 589nm generation for use in laser sodium guidestar generation is a key capability in today's modern adaptive optical systems. The approached used is Sum-Frequency Generation (SFG) of 1319nm and 1064nm lines of Nd:YAG in an LBO crystal. High power narrow line sources are not commercially available, so low power narrow-band NPRO sources are mated with resonantly tuned high power ring lasers to achieve high power ... |
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| Development of Nanoporous Carbide-Derived Carbon Electrodes for High-Performance Lithium-Ion Batteries |
Sep 2011 |
93 pages |
| Authors:
Kamryn M Sakamoto; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| Lithium ion batteries are the state-of-the-art power sources for portable electronic devices and, due to their superior energy and power densities, are promising candidates for the demanding energy storage applications of the U.S. Navy and other branches of the military. While graphitic carbon is currently the most common anode material in lithium ion batteries, it suffers from low specific capacity (372 mAh/g) and poor power characteristics. In contrast, amorphous carbons ... |
|
| TCAD Analysis of Heating and Maximum Current Density in Carbon Nanofiber Interconnects |
Sep 2011 |
87 pages |
| Authors:
Jason A Brunton; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
|
| As devices shrink, the current density through interconnects increases proportionally making new materials a necessity for industry growth. Carbon nanofiber (CNF) and carbon nanotube's (CNT) potential for high current density make them a possible replacement for metal contacts. Learning the limitations of CNFs and CNTs is important if they are to be used in next-generation electronics. As current density increases, heat is generated throughout the CNF structure. This heating eventually ... |
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| Time-resolved Langmuir Probing of a New Lanthanum Hexaboride (LaB6) Hollow Cathode |
Sep 2011 |
11 pages |
| Authors:
Kimberly R Trent; Michael S McDonald; Robert B Lobbia; Alec D Gallimore; MICHIGAN UNIV ANN ARBOR PLASMA DYNAMICS AND ELECTRIC PROPULSION LAB
|
| A new laboratory model lanthanum hexaboride (LaB6) hollow cathode sized for a 20 A HET discharge has been developed. The cathode design is based on previous high current LaB6 cathodes. The cathode s heating element, which is used to bring the insert to thermionic emission temperatures, is usually the most likely to break down. In this new LaB6 cathode, the heater has been redesigned to address various fail mechanisms such ... |
|
| A User-Friendly Tool for Evaluationg the Thermal Response of High Power Battery Packaging Alternatives |
02 AUG 2011 |
17 pages |
| Authors:
Stanley Jones; John Mendoza; George Frazier; Sonya Zanardelli; ARMY TANK AUTOMOTIVE RESEARCH DEVELOPMENT AND ENGINEERING CENTER WARREN MI
|
| Latest generation of high power battery cells are often comprised of multiple alternating layers of anode, cathode, separator and electrolyte. Macroscopically, battery cores represent an orthotropic material subject to a time variant heat source. Safety and performance considerations place a premium on packaging design and installation thermal maintenance. SAIC has developed a numerical solver tool to evaluate thermal performance of packaging alternatives. |
|
| Compact, High-Power, Low-Cost 295 nm DUV Laser by Harmonic Conversion of High Power VECSELs |
10 MAY 2011 |
9 pages |
| Authors:
Mahmoud Fallahi; ARIZONA UNIV TUCSON OPTICAL SCIENCES CENTER
|
| We have successfully demonstrated a compact high-power CW DUV source emitting at 295 nm exceeding the targeted objective. The laser is based on frequency-quadrupled optically pumped vertical external cavity surface emitting source. A highly-strained InGaAs/GaAs multi-quantum well semiconductor laser operating at 1178 nm in a single frequency is developed. By intracavity frequency doubling of the laser, multi-watt yellow laser emitting at 589 nm is generated. The single-frequency, intracavity-doubled 589-nm output ... |
|
| A Review of Heavy-Fueled Rotary Engine Combustion Technologies |
MAY 2011 |
96 pages |
| Authors:
Chol-Bum M. Kweon; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The rotary engine has been used as one of the powerplants for unmanned aerial vehicles because of its many merits, such as higher power density, light weight, simple design, smooth operation, low vibration, and compact size. However, it also has demerits, such as high fuel consumption and higher maintenance requirements. This report reviews the current status of the heavy-fueled rotary engine combustion technologies and gains insights into the technology gaps ... |
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| Coherent Combining of High-Power Yb Fiber Amplifiers |
20 Apr 2011 |
9 pages |
| Authors:
Charles X Yu; Steven J Augst; Shawn M Redmond; Kris C Goldizen; Daniel V Murphy; Antonio Sanchez; Tso Y Fan; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| Commercial 0.5-kW Yb-doped fiber amplifiers have been characterized and been found to be suitable for coherent beam combining. Eight such fiber amplifiers have been coherently combined in a tiled-aperture configuration with 78% combining efficiency. The power-in-the-bucket vertical beam quality of the combined output is 1.25 times diffraction limited at full power. The beam-combining performance is independent of output power. |
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| High-Energy Laser for Detection, Inspection, and Non-Destructive Testing |
21 MAR 2011 |
14 pages |
| Authors:
Donald Umstadter; Sudeep Banerjee; NEBRASKA UNIV LINCOLN DEPT OF PHYSICS AND ASTRONOMY
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| The central feature of the project was the development of a high-energy (30 J) high-power (petawatt) laser amplifier, which is seeded by an existing 100-terawatt, 30-fs laser system. This 2-pass, 10-cm aperture, Ti:Sapphire amplifier pumped by four high-energy (total of 100-J energy), high-repetition-rate (0.1 Hz), frequency-doubled Nd-Glass pump lasers, and a new, larger grating-based optical compressor, were installed in the Extreme Light Laboratory and successfully tested. The amplifier gain was ... |
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| Code TESLA for Modeling and Design of High-Power High-Efficiency Klystrons |
Mar 2011 |
4 pages |
| Authors:
I A Chernyavskiy; S J Cooke; B Levush; A N Vlasov; Jr Antonsen T M; NAVAL RESEARCH LAB WASHINGTON DC
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| This work gives an overview of the main features of the 2.5D large-signal code TESLA and its capabilities for the modelling single-beam and multiple-beam klystrons as high-power RF sources. These sources are widely used or proposed to be used in accelerators in the future. Comparison of TESLA modelling results with experimental data for a few multiple-beam klystrons are shown. |
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Reports by Keyword(s)
HIGH POWER
