| A New Spectro-Polarimeter for Solar Prominence and Filament Magnetic Field Measurements |
Nov-2009 |
11 pages |
| Authors:
David F Elmore; Roberto Casini; Greg L Card; Marc Davis; Alice Lecinski; Ron Lull; Peter G Nelson; Steven Tomczyk; NATIONAL CENTER FOR ATMOSPHERIC RESEARCH BOULDER CO
|
 | We are constructing a spectro-polarimeter using the 4 0-cm coronagraph at the Evans Solar Facility of the National Solar Observatory in Sunspot, NM for the purpose of measuring the vector magnetic filed in prominences and filaments. The Prominence Magnetometer (ProMag) is comprised of a polarization modulation package and a spectrograph. The modulation optics are located at the prime focus of the coronagraph along with calibration optics and a beamsplitter that ... |
|
| Development of a Charged-Particle Accumulator Using an RF Confinement Method |
29-Sep-2009 |
7 pages |
| Authors:
Ryogo S Hayano; TOKYO UNIV (JAPAN)
|
| This report describes the excellent progress made in constructing a Paul Trap, despite all the difficulties encountered by researchers at CERN. |
|
| Plasma-Based Surface Modification and Corrosion in High Temperature Environments |
05-Feb-2009 |
19 pages |
| Authors:
Todd Allen; Lizhen Tan; Kumar Sridharan; WISCONSIN UNIV-MADISON
|
| * Corrosion research at the University of Wisconsin is focused on two areas (i) plasma-based surface treatments to reduce corrosion, (ii) high temperature corrosion in harsh environments. * Plasma-based surface treatments (10 to 2000nm depth) have involved ion implantation and thin film deposition and atomic mixing approaches to mitigate corrosion and wear. * Specific testing equipment for corrosion testing in high temperatures and harsh environments such as supercritical water, molten ... |
|
| Experimental/Computational Approach to Accommodation Coefficients and its Application to Noble Gases on Aluminum Surface (Preprint) |
03-Feb-2009 |
26 pages |
| Authors:
Andrew Ketsdever; Sergey F Gimelshein; Nathaniel Selden; Natalie E Gimelshein; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| A technique is proposed to assess gas-surface accommodation coefficients. The technique utilizes the fact that radiometric forces exerted on heated objects immersed in rarefied gases are governed by the interaction of gas molecules with the surface. In the present implementation, it connects measurements of radiometric forces on a heated vane in the transitional flow regime with the kinetic modeling of the flow, and derives the accommodation coefficients through the successive ... |
|
| Pressurized Structure Technology for UAVS |
Dec-2008 |
10 pages |
| Authors:
H Edge; M Nixon; A Janas; W Ross; J Collins; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD VEHICLE TECHNOLOGY DIRECTORATE
|
| There is a critical need to improve the performance and utility of unmanned aerial vehicles (UAVs). Several areas of UAV performance need to be improved for the next generation of UAVS to be used successfully in expanded future combat roles. For example current time aloft is only on the order of an hour or two for electric-powered UAVs. The current generation of UAVs lacks vertical takeoff and landing (VTOL) capability ... |
|
| Modularity of the MIT Pebble Bed Reactor for Use by the Commercial Power Industry |
01-Jun-2008 |
|
| Authors:
Jaime E Hanlon-Hyssong; MASSACHUSETTS INST OF TECH CAMBRIDGE
|
 | The Modular Pebble Bed Reactor is a small high temperature helium cooled reactor that is being considered for both electric power and hydrogen production. Pebble bed reactors are being developed in South Africa, China and the US. To make smaller 120 Mwe reactors economically competitive with larger 1500 Mew traditional light water reactors changes in the way these plants are built are needed. Economies of production need to be efficiently ... |
|
| Magnesium Repair by Cold Spray |
MAY 2008 |
34 pages |
| Authors:
V. K. Champagne; P.F. Leyman; D. J. Helfritch; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| The U.S. Army has experienced significant corrosion problems with magnesium alloys that are used to fabricate aircraft components. The most severe of these are associated with large and expensive transmission and gearbox housings for rotorcraft, which have to be removed prematurely because of corrosion. Many of the parts cannot be reclaimed because there is not an existing technology that can restore them adequately for service. The U.S. Army Research Laboratory ... |
|
| Numerical and Experimental Investigation of Microchannel Flows with Rough Surfaces (Postprint) |
OCT 2007 |
10 pages |
| Authors:
T. C. Lilly; J. A. Duncan; S. L. Nothnagel; S. F. Gimelshein; N. E. Gimelshein; A. D. Ketsdever; I. J. Wysong; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| A conical surface roughness model applicable to particle simulations has been developed. The model has been experimentally validated for channel flows using helium and nitrogen gases at Reynolds numbers from 0.01 to 10 based on inlet conditions. To efficiently simulate gas-surface interaction, molecular collisions with the actual rough surface are simulated by collisions with a randomly positioned conical hole having a fixed opening angle. This model requires only one surface ... |
|
| Analysis of Required Supporting Systems for the Supercritical CO(2) Power Conversion System |
Sep-2007 |
|
| Authors:
Rosemary M Freas; MASSACHUSETTS INST OF TECH CAMBRIDGE
|
| Recently, attention has been drawn to the viability of using S-CO(2) as a working fluid in modern reactor designs. Near the critical point, CO2 has a rapid rise in density allowing a significant reduction in the compressor work of a closed Brayton Cycle. Therefore, 45% efficiency can be achieved at much more moderate temperatures than is optimal for the helium Brayton cycles. An additional benefit of the S-CO2 system is ... |
|
| On the Spectral Evolution of Cool, Helium-Atmosphere White Dwarfs: Detailed Spectroscopic and Photometric Analysis of DZ Stars |
10 JUL 2007 |
19 pages |
| Authors:
P. Dufour; P. Bergeron; James Liebert; H. C. Harris; G. R. Knapp; S. F. Anderson; Patrick B. Hall; Michael A. Strauss; Matthew J. Collinge; Matt C. Edwards; NAVAL OBSERVATORY WASHINGTON DC
|
| We present a detailed analysis of a large spectroscopic and photometric sample of DZ white dwarfs based on our latest model atmosphere calculations. We revise the atmospheric parameters of the trigonometric parallax sample of Bergeron, Leggett, & Ruiz (12 stars) and analyze 147 new DZ white dwarfs discovered in the SDSS. The inclusion of metals and hydrogen in our model atmosphere calculations leads to different atmospheric parameters than those derived ... |
|
| Experimental and Computational Observation of Radiometric Forces on a Plate (Preprint) |
12 JUN 2007 |
13 pages |
| Authors:
N. Selden; C. Ngalande; S. Gimelshein; A. Ketsdever; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| The radiometric force on several configurations of heated plates placed in a stagnant gas is examined experimentally on a high resolution thrust stand and numerically using the direct simulation Monte Carlo method. A wide range of pressures from 0.006Pa to 6Pa corresponding to Knudsen numbers from 20 to 0.02 is examined for nitrogen, argon, xenon, and helium test gases. It is shown that the force is maximum in the transition ... |
|
| Study of Cryogenic Complex Plasma |
26 APR 2007 |
9 pages |
| Authors:
Osamu Ishihara; Yoshiharu Nakamura; Masako Shindo; Chikara Kijima; YOKOHAMA NATIONAL UNIV (JAPAN) FACULTY OF ENGINEERING
|
| This Report describes the investigation entitled by "Study of Cryogenic Complex Plasma." The research has been carried out at Yokohama National University. Our overall goal is to study the cryogenic complex plasma experimentally and theoretically and to reveal novel natures of cryogenic complex plasma produced by a stable discharge above or in superfluid liquid helium. Two Dewar bottles, YD-1 (Yokohama Dewar 1) and YD-2 (Yokohama Dewar 2), accommodate cryogenic plasma ... |
|
| Wettability Tests of Polymer Films and Fabrics and Determination of Their Surface Energy by Contact-Angle Methods |
MAR 2007 |
18 pages |
| Authors:
Daphne Pappas; Craig Copeland; Robert Jensen; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| In this research, wettability testing was performed for nylon-6 and polyethylene films and ultra-high molecular weight polyethylene woven fabrics to examine the effects of surface atmospheric plasma treatment. |
|
| Preliminary Study of Arcjet Neutralization of Hall Thruster Clusters (Postprint) |
18 JAN 2007 |
22 pages |
| Authors:
Quentin E. Walker; Mark A. Cappelli; William A. Hargus; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| Clustered Hall thrusters have emerged as a favored choice for extending Hall thruster options to very high powers (50 kW - 150 kW). This paper examines the possible use of an arcjet to neutralize clustered Hall thrusters, as the hybrid arcjet-Hall thruster concept can fill a performance niche amongst available propulsion options. We examine missions on which this hybrid concept would be a competitive or favored thruster option, report on ... |
|
| Confocal Microscopy Studies for Plasma Surface Modified Films and Fibers |
DEC 2006 |
28 pages |
| Authors:
Donovan Harris; Daphne Pappas; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The focus of this work is plasma-treated Nylon 6 films and woven fabrics characterization by a confocal laser scanning microscope. The purposes of these efforts were the preliminary characterization of vendor-treated materials prior to equipment installation and the evaluation of instrumentation capability to provide the data required in a time-effective manner. Brief technical discussions of the atmospheric plasma process and some of the resultant surface chemistries are presented in conjunction ... |
|
| Aircraft Fuel Cell Repair Equipment (AFCRE) |
09 AUG 2006 |
11 pages |
| Authors:
John M. Yerger; AIR MOBILITY WARFARE CENTER FORT DIX NJ AIR MOBILITY BATTLELAB
|
| PROBLEM: Aircraft fuel cell repair time is quite lengthy due to dated troubleshooting tools, sealant cure time and repair validation. PROPOSED SOLUTION: Use helium gas to troubleshoot leaks and validate repairs. Use new technology to remove and cure sealant. |
|
| New Experimental Approaches and Theoretical Modeling Methods for Laser Cooling Atoms and Molecules |
27 JUL 2006 |
13 pages |
| Authors:
T. H. Bergeman; H. J. Metcalf; STATE UNIV OF NEW YORK AT STONY BROOK RESEARCH FOUNDATION
|
| The first part of this project involved continued development of theoretical models of diatomic molecular electronic level structure for application to the production of ultracold diatomic molecules via photoassociation. Recently, there has been considerable interest in producing molecules at the temperatures achieved for laser-cooled atoms, for applications to "coherent chemistry," studies of molecule-atom and molecule-molecule interactions. Bose condensates of molecules and for quantum computing. It is advantageous to produce cold ... |
|
| Surface Roughness Effects in Low Reynolds Number Channel Flows (POSTPRINT) |
JUL 2006 |
9 pages |
| Authors:
N. Gimelshein; J. Duncan; T. Lilly; S. Gimelshein; A. Ketsdever; I. Wysong; ENGINEERING RESEARCH AND CONSULTING INC (ERC INC) EDWARDS AFB CA
|
| Rarefied helium and nitrogen flow expanding into vacuum through 150 micron high and 1.5 cm long channels is studied experimentally and numerically with the DSMC method. Different types of channel walls are examined, both polished and rough with well characterized roughness shaped as triangles and rectangles. The pressure varies from 200 to 13,000 Pa, with the gas mean free path being both much larger and much smaller than the roughness ... |
|
| Surface Roughness Effects in Low Reynolds Number Channel Flows |
12 JUN 2006 |
9 pages |
| Authors:
N. Gimelsheim; J. Duncan; T. Lilly; S. Gimelshein; A. Ketsdever; I. Wysong; ERC INTERNATIONAL INC SAN DIEGO CA
|
| Rarefied helium and nitrogen flow expanding into vacuum through 150 micrometers high and 1.5 cm long channels is studied experimentally and numerically with the DSMC method. Different types of channel walls are examined, both polished and rough with well characterized roughness shaped as triangles and rectangles. The pressure varies from 200 to 13,000 Pa, with the gas mean free path being both much larger and much smaller than the roughness ... |
|
| Investigation into the Feasibility of Highly Enriched Uranium Detection by External Neutron Stimulation (Expanded Study) |
MAY 2006 |
238 pages |
| Authors:
Martin E. Nelson; James F. Ziegler; Harry F. Feigel; Crystine M. Good; Bryan N. Blackburn; Joseph S. St. John; Sean J. Locke; Jeffrey D. Allen; NAVAL ACADEMY ANNAPOLIS MD DEPT OF MECHANICAL ENGINEERING
|
| This report studied the detectability of 1kg of HEU in a cargo container, whose dimensions are 20'x8'x8', by stimulating the HEU with neutron source located external to the container and counting the neutrons that would be produced with a high sensitivity thermal neutron detector. This project examined a wide variety of different energy sources, counting options, and the effect of different cargo materials present within the container. The study considered ... |
|
| Electromagnetic Launching for Affordable Agile Access to Space |
15 APR 2006 |
71 pages |
| Authors:
Rainer Meinke; Hector Guiterrez; Daniel Kirk; ADVANCED MAGNET LAB INC MELBOURNE FL
|
| The conceptual design of a novel hypersonic electromagnetic launch system has been developed, which offers reliable access to space. While the concept can be scaled in both mass and launch speed, the performed study assumes a 100-kg projectile leaving the launcher at 7,000 m/sec. The projectile is propelled and levitated by electromagnetic forces inside of a low pressure tube filled with helium at about 10 torr. A fully controlled acceleration ... |
|
| Improved Chemical Protective Gloves Using Elastomeric Nanocomposites |
06 FEB 2006 |
35 pages |
| Authors:
Harris A. Goldberg; Carrie A. Feeney; INMAT LLC HILLSBOROUGH NJ
|
| Nanocomposite Coatings of neoprene and nitrile Rubber based on InMat's environmentally friendly, water based, Nanolok coating technology have been developed. In this report, we discuss the optimization and scale up of these coating formulations that are targeted for use in multilayer chemical protective gloves. Such gloves will provide the protection of butyl based gloves while having significantly improved resistance to petroleum oils and gasoline while also being less flammable. There ... |
|
| Collisional Stabilization of Highly Vibrationally Excited Omicron-, Mu- and Rho-Xylene Ions (C8H10+) from 300-900 K and 1-250 Torr |
2006 |
7 pages |
| Authors:
AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE
|
|
| Development and Optimization of a Tridyne Pressurization System for Pressure Fed Launch Vehicles |
2006 |
14 pages |
| Authors:
Shyama Chakroborty; Mark Wollen; Lee Malany; MICROCOSM INC EL SEGUNDO CA
|
| Over the recent years, Microcosm has been pursuing the development of a Tridyne-based pressurization system and its implementation in the Scorpius family of launch vehicles to obtain substantial gain in payload to orbit. This technology program was initiated with an IR&D program and matured with contracts from the National Reconnaissance Office (NRO), and the Air Force Research Laboratory (AFRL). The Tridyne pressurization system functions by mixing small amounts of hydrogen ... |
|
| Characterization of Plasma Etch Processes for Wide Bandgap Semiconductors |
07 SEP 2005 |
12 pages |
| Authors:
Karen J. Nordheden; KANSAS UNIV LAWRENCE CENTER FOR RESEARCH IN ENGINEERING SCIENCE
|
| We have completed etch rate determination and plasma diagnostics using optical emission spectroscopy, mass spectrometry, and microwave measurements of average electron densities. The previous diagnostics indicate that the observed etch rate enhancement might be due to in part to an increase in the overall electron density (but not enough to account for the entire etc rate enhancement) and a probable increase in the average electron temperature (energy), both of which ... |
|
| Control of High-Speed Flows Using Helium Injection |
24 AUG 2005 |
17 pages |
| Authors:
Alexander J. Smits; Richard B. Miles; PRINCETON UNIV NJ
|
| Here, we summarize the results of our investigation of means for controlling high-speed flows using helium injection, first demonstrated by Auvity et al., with particular emphasis on the wavefront distortion of light transmitted through the boundary layer. Quantitative estimates of wavefront distortion were obtained, with and without helium injection, and new diagnostic techniques were developed, including a MHz rate Hartmann wavefront sensor. In particular, we demonstrated the ability to capture ... |
|
| Characterization and Optimization of a Radiantly Driven Multi-Stage Knudsen Compressor |
13 JUL 2005 |
7 pages |
| Authors:
M. Young; Y. L. Han; E. P. Muntz; Geoff Shiflett; UNIVERSITY OF SOUTHERN CALIFORNIA LOS ANGELES DEPT OF AEROSPACE AND MECHANICAL ENGINEERING
|
| The Knudsen Compressor is a micro/meso-scale gas roughing pump that operates by utilizing the thermal transpiration effect. A Finite Element Knudsen Compressor Performance Model was constructed and used to investigate the pumpdown performance of large-scale Knudsen Compressor cascades. Model predictions were compared to experimental measurements made for radiantly driven Knudsen Compressors of up to 15 stages. The temperature difference maintained across the thermal transpiration membrane was measured and agreed with ... |
|
| Experimental and Numerical Study of Nozzle Plume Impingement on Spacecraft Surfaces |
13 JUL 2005 |
7 pages |
| Authors:
A. D. Ketsdever; T. C. Lilly; S. F. Gimelshein; A. A. Alexeenko; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| An experimental and numerical effort was undertaken to assess the effects of a cold gas (To=300K) nozzle plume impinging on a simulated spacecraft surface. The nozzle flow impingement is investigated experimentally using a nano-Newton resolution force balance and numerically using the Direct Simulation Monte Carlo (DSMC) numerical technique. The Reynolds number range investigated in this study is from 0.5 to approximately 900 using helium and nitrogen propellants. The thrust produced ... |
|
| Stationary Population Inversion in an Expanding Argon Plasma Jet by Helium Puffing |
13 JUL 2005 |
7 pages |
| Authors:
H. Akatsuka; K. Kano; TOKYO INST OF TECH (JAPAN) RESEARCH LAB FOR NUCLEAR REACTORS
|
| An experiment of He gas-contact for generating population inversion in a recombining Ar plasma jet is carried out. Population inversion between Ar I excited states 5s'->4p'[1/2]1 and 5s'->4p[3/2]1,2, [5/2]2,3 is created by helium gas-contact cooling of electrons, whereas it is not created without gas-contact. Ar I lines 1.14 m, 1.34 m, and 1.09 m are strongly enhanced due to the He gas cooling. It is experimentally found that helium gas ... |
|
| Experimental and Numerical Modeling of Rarefied Gas Flows Through Orifices and Short Tubes |
13 JUL 2005 |
8 pages |
| Authors:
S. F. Gimelshein; G. N. Markelov; T. C. Lilly; N. P. Selden; A. D. Ketsdever; UNIVERSITY OF SOUTHERN CALIFORNIA LOS ANGELES
|
| Flow through circular orifices with thickness-to-diameter ratios varying from 0.015 to 1.2 is studied experimentally and numerically with kinetic and continuum approaches. Helium and nitrogen gases are used in the range of Reynolds numbers from 0.02 to over 700. Good agreement between experimental and numerical results is observed for mass flow and thrust corrected for the experimental facility background pressure. For thick-to-thin orifice ratios of mass flow and thrust vs ... |
|
| Kinetics of Thermal Decomposition of Aluminum Hydride: I-non-Isothermal Decomposition Under Vacuum and in Inert Atmosphere (Argon) |
06 MAY 2005 |
13 pages |
| Authors:
I. M. Ismail; T. Hawkins; AIR FORCE RESEARCH LAB EDWARDS AFB CA
|
| Recently, interest in alane (aluminum hydride) has been renewed as a rocket propulsion ingredient due to improvements in its manufacturing process and an increase in thermal stability. When alane is added to solid propellant formulations, rocket performance is enhanced and the specific impulse increases. Preliminary work was performed at AFRL on the characterization and evaluation of two alane samples. Decomposition kinetics have been determined from gravimetric TGA data and volumetric ... |
|
| NiAl Bond Coats Made by a Directed Vapor Deposition Approach |
OCT 2004 |
11 pages |
| Authors:
Z.. Yu; D. D. Hass; H. N. Wadley; VIRGINIA UNIV CHARLOTTESVILLE DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Intermetallic, nickel aluminide alloys are widely used as bond coat materials in thermal barrier coating systems applied to nickel base super alloy components. They are usually synthesized by a solid-state reaction diffusion heat treatment following the chemical vapor deposition of aluminum on the nickel rich substrate. Here, an electron beam directed vapor deposition (EB-DVD) technique is used to simultaneously evaporate nickel and aluminum and then reactively deposit NiAl bond coats ... |
|
| International Conference on Low Temperature Chemistry, LTC5, (5th) Held in Berlin-Dahlem, Germany on September 7-10, 2004. Final Proceedings Abstracts |
20 SEP 2004 |
124 pages |
| Authors:
Nikolaus Schwentner; Ingeborg Twesten; FREIE UNIV BERLIN (GERMANY F R)
|
| The Final Proceedings for Fifth International Conference on Low Temperature Chemistry (LTC5) 7 September 2004 - 10 September 2004. The proceedings are abstracts only. Topics covered include: Quantum solid: hydrogens and condensates, Quantum liquid: helium and nanodroplets, Tunneling and transport processes, Coherence and quantum chemical dynamics, Dynamics and femtochemistry, STM induced chemistry, Chemistry on surfaces and in nano materials, Reactions in clusters, Matrix isolation, Rare gas compounds, Cooled biomolecules, Astro- ... |
|
| Investigations of Vapor-Cell Clock Equilibration Following Initial Activation: A Progress Report |
SEP 2004 |
10 pages |
| Authors:
S. Herbulock; C. Klimcak; A. Presser; J. Milne; J. Camparo; AEROSPACE CORP LOS ANGELES CA
|
| Over the past several years, anecdotal evidence has grown indicating that Rb gas-cell frequency standards exhibit a long equilibration period of somewhere between 30 and 70 days following their initial activation. The mechanism driving this behavior is not well understood and has been the subject of debate. Generally, lamp intensity has also been observed to undergo a slow variation following the clock s turn-on, and since the clock s resonant ... |
|
| Experimental and Numerical Determination of Micropropulsion Device Efficiencies at Low Reynolds Numbers |
SEP 2004 |
47 pages |
| Authors:
Andrew D. Ketsdever; Michael T. Clabough; Sergey F. Gimelshein; Alina Alexeenko; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| The need for low thrust propulsion systems for maneuvers on micro- and nano-spacecraft is growing. Low thrust characteristics generally lead to low Reynolds number flows from propulsive devices that utilize nozzle expansions. Low Reynolds number flows of helium and nitrogen through a small conical nozzle and a thin-walled orifice have been investigated both numerically, using the Direct Simulation Monte Carlo technique, and experimentally, using a nano-Newton thrust stand. For throat ... |
|
| The Growth and Characterization of Metastable Free Radical Nanoclusters |
JUN 2004 |
7 pages |
| Authors:
Roger E. Miller; NORTH CAROLINA UNIV AT CHAPEL HILL DEPTOF CHEMISTRY
|
| In the first three years of this grant we have made considerable progress towards the goals stated in the original proposal. To date we have made clean sources for propargyl radical, CH3, F, Cl, Br and I. A total of 11 papers have been published during this grant period. |
|
| Formation of Electron Beam and Volume Discharge in Air under Atmospheric Pressure |
07 APR 2004 |
3 pages |
| Authors:
V. F. Tarasenko; V. M. Orlovskii; RUSSIAN ACADEMY OF SCIENCES TOMSK INSTOF HIGH CURRENT ELECTRONICS
|
| The conditions to form electron beams in air, nitrogen, and in the mixture CO2 - N2 - He under atmospheric pressure have been examined experimentally. At nanosecond pulses applied to the diode, e-beam was obtained in air with amplitude of 70 Angstrom. Electron beam appears at voltage pulse leading edge having duration at FWHM not higher than 0,4 ns. After beam current ends, the discharge is usually continued in quasi-stationary ... |
|
| Investigation of AlfVen Waves in a Helicon Plasma |
07 APR 2004 |
2 pages |
| Authors:
Albrecht Stark; Olaf Grulke; Thomas Klinger; ERNST-MORITZ-ARNDT-UNIVERSITY GREIFSWALD (GERMANY)
|
| Helicon wave sustained discharges provide high density plasmas needed to investigate Alfven waves under laboratory conditions. In the present paper kinetic Alfven waves were successfully launched in a helium plasma. A good agreement is found between the measured and the theoretically predicted dispersion behavior. The damping can be associated both to collisional and Landau damping. |
|
| Plasma Channel Dynamics Created by High-Current Relativistic Electron Beam When Being Distributed in Gaseous Media of Various Types |
07 APR 2004 |
2 pages |
| Authors:
N. A. Kondratiev; G. E. Remnev; V. I. Smetanin; TOMSK POLYTECHNIC UNIV (RUSSIA) NUCLEAR PHYSICS INST
|
| Experimental results of determination of plasma channel dynamics created by high-current beam (energy of electrons E(sub e) =1,1 x 10(exp 6) eV, beam current I(sub b)=2,4 x 10(exp 4) A, with pulse duration t=60 x 10(exp -9) c.) in gases: helium (He), nitrogen (N(sub 2)), neon (Ne), Air (Air),argon (Ar), krypton (Kr), xenon (Xe), humid air (Air:water) at pressure from 1 to 760 Tor are presented. It is showed that ... |
|
| Determination of Gas Temperature in Cathode Fall of the Self-Sustained Normal Atmospheric Pressure DC Glow Discharge |
07 APR 2004 |
2 pages |
| Authors:
V. I. Arkhipenko; A. A. Kirillov; L. V. Simonchik; S. M. Zgirouski; NATIONAL ACADEMY OF SCIENCES MINSK (BELARUS)
|
| The result of gas temperature measurements in cathode region of atmospheric pressure glow discharge in helium are presented. Temperature was determined using molecular bands of the first negative system of nitrogen (0,1) and OH (A(exp 2)SIGMA(+)-X(exp 2)pi) (0,0) band. The obtained results are compared with calculated one using one-dimensional model of the cathode fall taking into account the volumetric heat generation. |
|
| Quantitative Detection of Single O2 by Cavity-Enhanced Absorption |
11 DEC 2003 |
4 pages |
| Authors:
Skip Williams; Manish Gupta; Thomas Owano; Douglas S. Baer; Anthony O'Keefe; AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE
|
| A method for the practical determination of the absolute concentration of single alpha(exp 1) DELTA(sub g) oxygen is discussed. The method is based on sensitive, off-axis integrated-cavity-output spectroscopy (ICOS). Off-axis ICOS allows narrowband, continuous-wave lasers to be used in conjunction with optical cavities to record sensitive absorption measurements. The details of the method as well as spectroscopic data confirming the first observation of the (1,0) band of the beta(exp 1) ... |
|
| Arcjet Neutralization of Hall Thrusters. II: Experimental Demonstration |
03 OCT 2003 |
29 pages |
| Authors:
Quentin E. Walker; N. Gascon; Mark A. Cappelli; William A. Hargus Jr.; John A. Schilling; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| This paper examines the use of an arcjet to neutralize Hall thrusters, as such a hybrid arcjet-Hall thruster concept can fill a performance niche amongst available space propulsion options. We report on experiments that determine how much electron current can be drawn to a surrogate anode from the plume of low power arcjets operating on hydrogen and helium, and demonstrate the first successful operation of a low power Hall thruster-arcjet ... |
|
| Diffuse Dielectric Barrier Discharges in Nitrogen-Containing Gas Mixture |
20 JUL 2003 |
2 pages |
| Authors:
R. Brandenburg; H. -E. Wagner; P. Michel; D. Trunec; P. Stahel; MASARYK UNIV BRNO (CZECHOSLOVAKIA)
|
| Diffuse dielectric barrier discharges are investigated in mixtures of nitrogen with several noble gases (He, Ne, Ar). The results show that the discharge remains in the diffuse mode at relatively high content of the noble gases, which is contrary to the admixture of oxygen to nitrogen. |
|
| Mixing Characteristics of Coaxial Injectors at High Gas/Liquid Momentum Ratios |
04 JUN 2003 |
11 pages |
| Authors:
P. A. Strakey; D. G. Talley; J. J. Hutt; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| A study of the spray of a swirl coaxial gas-liquid injector operating at high-liquid momentum ratios is reported. Mixing and droplet size characteristics of the swirl injector are also compared to a shear coaxial injector, currently being used in the space shuttle main engine fuel preburner. The injectors were tested at elevated chamber pressures using water as a liquid oxygen stimulant and nitrogen and helium as gaseous hydrogen simulants. The ... |
|
| Empirical Evaluation of the MK 16 MOD 1 UBA Breathe-Down Procedure |
JUN 2003 |
47 pages |
| Authors:
Wayne A. Gerth; Keith A. Gault; Stephen J. Stanek; NAVY EXPERIMENTAL DIVING UNIT PANAMA CITY FL
|
| Guidance for using new helium-oxygen (Me-C2) decompression tables for the MK 16 MOD 1 underwater breathing apparatuS (UBA) includes recommended performance of a predescent breathe-down procedure (SOP) to reduce descent-induced overshoot of diver-inspired oxygen partial pressure (002). This report describes work completed at NEDU to test the efficacy of this procedure. Thirty-two MK 16 MOD 1 Me-C2 man-dives to 300 feet of seawater (fsw) were completed in the NEDU Ocean ... |
|
| Theory of Gas Adsorption in Carbon Nanostructures |
20 MAY 2003 |
5 pages |
| Authors:
Milton W. Cole; Vincent H. Crespi; J. K. Johnson; PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF PHYSICS
|
| This report is a brief summary of the results of studies conducted by faculty, students, and postdoctoral fellows at Pennsylvania State University (Department of Physics) and the University of Pittsburgh (Department of Chemical and Petroleum Engineering) on gas adsorption in carbon nanostructures. The principal research methods employed in these studies were analytical or numerical theory and computer simulation. In addition, successful collaborations with experimental scientists at these institutions and elsewhere ... |
|
| Numerical Simulations of Supersonic Flow Over an Elliptic Projectile with Jet Interaction |
MAY 2003 |
28 pages |
| Authors:
Jubaraj Sahu; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Computational fluid dynamics (CFD) approaches were used to compute the supersonic flow fields and aerodynamic forces and moments on an elliptic projectile with jet interaction. Steady state numerical results have been obtained for the jet interaction problem at a supersonic Mach number, Mach = 4. 0, and several angles of attack from 0 deg to 12 deg via Navier-Stokes computational techniques. The jet modeled in this problem is a supersonic ... |
|
| Coaxial Injection under Supercritical Conditions |
JAN 2003 |
3 pages |
| Authors:
Bruce Chehroudi; Doug Talley; ENGINEERING RESEARCH AND CONSULTING INC(ERC INC) EDWARDS AFB CA
|
| This work reports on findings from the initial phase of a coaxial injection process under both subcritical and supercritical conditions. The results presented here are part of a systematic investigation of common rocket engine injectors, such as impinging and coaxial designs. Liquid nitrogen (LN2) is injected through a large length-to-diameter ratio circular hole and exposed at the exit to an annular jet of different gases including nitrogen, helium, and argon. ... |
|
| Significant Increase in the Cryogenic Pumping System Capacity and Reliability for the CHAFF-IV Plume and Contamination Facility |
12 DEC 2002 |
21 pages |
| Authors:
E. P. Muntz; UNIVERSITY OF SOUTHERN CALIFORNIA LOS ANGELES DEPT OF AEROSPACE AND MECHANICAL ENGINEERING
|
| The interactions between exhaust plumes and the ambient, high altitude atmosphere have been investigated by the components of the Department of Defense for many years. To date, laboratory investigations of space plumes from firing thrusters and simulated ambient environments have been difficult to achieve due to limitations in pumping speed. The major limitation of ground- based facilities in accurately predicting the effects of thruster operation on spacecraft systems has always ... |
|
| Computational Issues in Analysis and Design of Chemical-Laser Flow- Fields |
30 SEP 2002 |
62 pages |
| Authors:
W. M. Eppard; Eugene M. Cliff; AEROSOFT INC BLACKSBURG VA
|
| In support of the Air Force's airborne laser (ABL) development program. state-of-the-art CFD analysis and design methods have been extended to include the physical models important in chemical oxygen-iodine laser (COIL) systems. The three-dimensional COIL simulation model is based on the CFD flow solver GASP v4 which solves the conservative, finite-volume formulation of the Navier-Stokes equations with general thermo-chemistry. The COIL design software is based on the continuous sensitivity equation ... |
|
Reports by Keyword(s)
HELIUM
