| Simulation of Gas-Filled Diodes With the VORPAL Code |
28 SEP 2005 |
21 pages |
| Authors:
Peter Stoltz; Chet Nieter; Jean-Luc Cambier; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
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 | Researchers are interested in rapid switching high-current diodes for applications including accelerators, microwave sources, and flat panel displays. Gas-filled diodes, such as the pseudospark, are one class of candidates for such high-current applications. To yield a better understanding of their operation, numerical simulations of these devices must include a number of physical processes: gas ionization, secondary electron emission and ion-induced electron emission, and radiation. We are enhancing the VORPAL code ... |
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| Carbon Materials Research |
AUG 2005 |
11 pages |
| Authors:
Wesley P. Hoffman; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
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| A basic research study in carbon materials for propulsion applications led to research in seemingly diverse areas, which include carbon-carbon composite fabrication, oxidation protection of carbon, microelectromechanical (MEMs) devices, and surface tension phenomenon. Carbon-carbon composites are the material of choice in many high temperature thermostructural applications, such as, rocket nozzles and exit cones, missile nosetips, and leading edges of hypersonic vehicles. Although these material are stronger than steel, stiffer than ... |
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| Predicting the Crack Growth Behavior in a Filled Elastomer (Briefing Charts) |
AUG 2005 |
13 pages |
| Authors:
C. T. Liu; Max Yen; C. K. Ching; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
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| Objectives of this study is to investigate the effect of confining pressure on the crack growth behavior in the material, and to predict the crack growth behavior in the material. |
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| Chemistry in Action: Space Shuttle Fuel Chemistry |
AUG 2005 |
32 pages |
| Authors:
Ghanshyam L. Vaghjiani; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
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| Carbon Materials Research |
14 JUL 2005 |
7 pages |
| Authors:
Wesley P. Hoffman; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
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| Carbon-carbon composites have been used by the Air Force and others for over 25 years in a variety of thermostructural applications including rocket propulsion, re-entry, hypersonics and aircraft brakes. Although the technology is mature, these materials are still very expensive, have long lead-times, are limited in thickness, are not uniform in density, and cannot be used in an oxidizing environment for extended periods without some type of protection. There is ... |
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| Laser-Induced Fluorescence of Neutral Xenon in the Near Field of a 200 W Hall Thruster |
JUL 2005 |
11 pages |
| Authors:
William A. Hargus Jr; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
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| This work presents measurements of neutral xenon velocity in the plume of the Busek Company BHT-200-X3 200 W Hall thruster at a single 250 V anode potential operating condition. The xenon velocities were measured using laser induced fluorescence of the 6s'1/20/1 -6p'3/22 excited state transition at 834.68 nm. Velocities were interrogated near the exit plane of the anode discharge and in the vicinity of the cathode. Both axial and radial ... |
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| Energetic Ionic Liquids as TNT Replacements (Briefing Charts) |
JUN 2005 |
19 pages |
| Authors:
T. W. Hawkins; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
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| Presentation on the use of energetic ionic liquids as a substitute for TNT in melt-cast explosives. |
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| Ionic Liquids Research and Development - US Air Force Research Laboratory. Molecular Dynamics Contractors Meeting |
24 MAY 2005 |
14 pages |
| Authors:
Tim Hawkins; Stefan Schneider; Angelo Alfano; Gammy Vaghjiani; Jeff Mills; Leslie Hall; Donald Tzeng; Jerry Boatz; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
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| This documents reports on: 1) Recent Ionic Liquid Synthesis and Characterization; 2) Ionic Liquid Fuel for Biopropulsion; 3) Ionic Liquids in Munitions; 4) Energetic Ionic Liquids for TNT Replacements; and 5) Theoretical Performance. |
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| ExB Measurements of a 200 W Xenon Hall Thruster |
MAY 2005 |
10 pages |
| Authors:
J. M. Ekholm; W. A. Hargus Jr.; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
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| Angularly resolved ion species fractions of Xe+1, Xe+2, and Xe+3 in the Busek BHT-200-X3 xenon Hall thruster plume were measured using an ExB probe for several operating conditions. The thruster was operated at nominal anode potential of 250 V and swept from 200 V to 325 V in 25 V increments. The ExB probe was placed 60 cm downstream of the exit plane and rotated up to 90 degrees from ... |
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| Optical Boron Nitride Insulator Erosion Characterization of a 200 W Xenon Hall Thruster |
MAY 2005 |
11 pages |
| Authors:
William A. Hargus Jr; Joshua Strafaccia; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
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| Vacuum ultraviolet emission (137.9 nm) of boron neutrals sputtered from a 200 W xenon Hall thruster boron nitride insulator is evaluated as a diagnostic for real-time evaluation of thruster insulator erosion. Three Hall thruster plasma control variables are examined: ion energy (discharge potential), ion flux (propellant flow), and plasma conductivity (magnetic field strength). The boron emission, and hence the insulator erosion rate, varies linearly with ion energy and ion flux. ... |
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| 248-NM Laser Photolysis of CHBr3/O-Atom Mixtures: Kinetic Evidence for UV CO(A)-Chemiluminescence in the Reaction of Methylidyne Radicals with Atomic Oxygen |
APR 2005 |
19 pages |
| Authors:
Ghanshyam L. Vaghjiani; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
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| A 90 GHz Phase-Bridge Interferometer for Plasma Density Measurements in the Near Field of a Hall Thruster |
2001 |
9 pages |
| Authors:
Mark Cappelli; Wes Hermann; Michael Kodiak; Nicolas Gascon; William Hargus Jr; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
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| Preliminary measurements are described of electron number density obtained in the near field of a 200W Busek Hall thruster. The approach taken is ultra-high high frequency (3.3 mm wavelength, 90 GHz) microwave interferometry that affords high spatial resolution suitable for studying the near exit region, where the plasma density can be as high as 10 (11)cm-3. A 90 GHz beam can be focused down to a waist of approximately 7 ... |
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| The Case for Small Spacecraft: An Integrated Perspective on Electric Propulsion |
1995 |
13 pages |
| Authors:
D. Barnhart; R. Wojnar; D. Tilley; R. Spores; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
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| As economies of scale were reduced in commercial and military endeavors, and with the international climate trending toward cooperation and stabilization, the aerospace industry today has taken a decided turn toward decreasing expenditures. This reduction in funding has challenged project managers and engineers to reduce the overall size of spacecraft while still accomplishing the same or similar tasks as larger spacecraft. Solutions to reconnaissance, environmental monitoring, and ground imaging are ... |
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| Electric Propulsion for an Interplanetary Astrophysics Mission |
1995 |
10 pages |
| Authors:
B. T. Patel; M. Martinez-Sanchez; G. R. Ricker; D. Tilley; D. Barnhart; H. Alexander; R. Myers; E. Pencil; G. Horvat; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
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| The Energetic Transient Array (ETA) is a mission, proposed by the Center for Space Research (CSR) at MIT, to set up an interplanetary constellation of six microsatellites for Gamma Ray Burst (GRB) astrometry. The micro-satellites will be deployed into distinct heliocentric orbits by a carrier spacecraft which will be propelled by a stationary plasma (SPT-79) electric thruster. This paper presents a discussion of the issues related to the application of ... |
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