| On the Accuracy of Thermionic Electron Emission Models. I. Electron Detachment from SF6(-) |
Jun-2009 |
13 pages |
| Authors:
Jurgen Troe; Thomas M Miller; Albert A Viggiano; GOETTINGEN UNIV (GERMANY F R) INST FUER PHYSIKALISCHE CHEMIE
|
 | Detailed statistical rate calculations combined with electron capture theory and kinetic modeling for the electron attachment to SF6 and detachment from SF6(-) [Troe et al., J. Chem. Phys. 127, 244303 (2007)] are used to test thermionic electron emission models. A new method to calculate the specific detatchment rate constants k(det)(E) and the electron energy distributions f(E, epsilon) as functions of the total energy E of the anion and the energy ... |
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| Quenching Dynamics of Electronically Excited Hydroxyl Radicals |
19 MAY 2008 |
6 pages |
| Authors:
Marsha I. Lester; PENNSYLVANIA UNIV PHILADELPHIA
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| Collisional quenching of electronically excited OH radicals by molecular partners has been investigated over the past 25 years, principally by evaluating the quenching cross sections for partners of aeronautical, atmospheric, and/or combustion relevance. Yet little is known about the outcome of these electronic quenching events, except that they facilitate the efficient removal of OH from the excited Alpha 2sigma+ electronic state by introducing nonradiative decay pathways. Most recently, we carried ... |
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| Dependence of Electron Peak Current on Hollow Cathode Dimensions and Seed Electron Energy in a Pseudospark Discharge (Preprint) |
03 JUN 2007 |
25 pages |
| Authors:
S. O. Cetiner; P. Stoltz; P. Messmer; Jean-Luc Cambier; TECH-X CORP BOULDER CO
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| The pre-breakdown and breakdown phases of a pseudospark discharge are investigated using the two-dimensional kinetic plasma simulation code OOPIC Pro. Trends in the peak electron current at the anode are presented as function of the hollow cathode dimensions and mean seed injection velocities at the cavity back wall. The plasma generation process by ionizing collisions is examined, showing the effect on supplying the electrons that determine the density of the ... |
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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
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| 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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| Computational Model of One-Dimensional Dielectric Barrier Discharges |
JUN 2005 |
111 pages |
| Authors:
Krista G. Marchand; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT/DEPT OF ENGINEERING PHYSICS
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| A one-dimensional fluid model of a surface-type dielectric barrier discharge is created using He as the background gas. This simple model, which only considers ionizing collisions and recombination in the electropositive gas, creates an important framework for future studies into the origin of experimentally observed flow control effects of the DBD. The two methods employed in this study include the semi-implicit sequential algorithm and the fully implicit simultaneous algorithm. The ... |
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| The Convergence of CASSCF Energies to the Complete Basis Set Limit |
APR 2005 |
18 pages |
| Authors:
George A. Petersson; David K. Malick; Michael J. Frisch; Matthew Braunstein; WESLEYAN UNIV MIDDLETOWN CT HALL-ATWATER LABS
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| Examination of the convergence of full valence CASSCF energies with expansion of the one-electron basis set reveals a pattern very similar to the convergence of single determinant Hartree-Fock energies. Calculations on twenty-six molecular examples with the sequence of ntuple-sigma augmented polarized (nZaP) basis sets (n = 2, 3, 4, 5, and 6) are used to evaluate complete basis set (CBS) extrapolation schemes. The most effective extrapolation reduces the RMS one-electron ... |
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| Capacitance-Voltage Study on the Effects of Low Energy Electron Radiation on Al(0.27)Ga(0.73)N/GaN High Electron Mobility Transistors |
MAR 2005 |
143 pages |
| Authors:
Thomas D. Jarzen; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| The effects of radiation on semiconductors are extremely important to the Department of Defense since the majority of the defense informational, navigational and communications systems are now satellite-based. Due to the high radiation tolerance of gallium nitride and a plethora of high temperature, high power and high frequency applications, the prospect that gallium nitride based devices will become key components in a multitude of military satellite-based systems is highly probable. ... |
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| Characterization of Dislocation Core Structures in BCC Metals |
30 AUG 2004 |
17 pages |
| Authors:
Kevin J. Hemker; JOHNS HOPKINS UNIV BALTIMORE MD DEPT OF MECHANICAL ENGINEERING
|
| The scientific aim of this study was to use state-of-the-art TEM techniques to experimentally describe dislocation core structures in bcc metals through experimental characterization of screw dislocations in single-crystalline Mo. Methods were developed for deriving localized electron structure data from electron energy loss spectra (EELS) taken from perfect lattice regions and along dislocations and low angle boundaries in ordered NiAl. Significant changes in the fine structure of the NiL edge ... |
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| High Resolution Chemical Microscopy for Materials Science |
18 SEP 2003 |
5 pages |
| Authors:
R. W. Carpener; W. Petuskey; D. J. Smith; ARIZONA STATE UNIV TEMPE CENTER FOR SOLID STATE SCIENCE
|
| This project is for purchase and installation of a high resolution analytical transmission electron microscope. The microscope has been delivered, installed in a specially prepared laboratory area, and thoroughly checked out. It met all performance test and was formally accepted on September 1, 2003, two weeks after the final peripheral hardware was installed by the manufacturer and checked out successfully. The start date for the project was June 1, 2000. ... |
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| Resonance Effects of the Electron Distribution Function Formation in Spatially Periodic Fields |
20 JUL 2003 |
2 pages |
| Authors:
Yu. B. Golubovskii; R. V. Kozakov; C. Wilke; J. Behnke; V. Nekutchaev; SAINT PETERSBURG STATE UNIV (RUSSIA)
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| Calculations of the electron energy distribution function (EEDF) in the striation-like sine modulated electric field are performed. Dependence on a spatial period length was investigated. Calculations were made for discharge conditions pR=2 Torr cm and i/R= 5 mA/cm and electric field E/p= 1.9 V/cm Torr. The presence of the resonance on the EEDF and macroscopic parameters are demonstrated. These resonances correspond to S- and P- striations that could be observed ... |
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| Electron Energy Deposition in an E-Beam Pumped KrF Amplifier: Impact of the Gas Composition |
23 DEC 2002 |
28 pages |
| Authors:
J. L. Giuliani; G. M. Petrov; A. DASGUPTA; NAVAL RESEARCH LAB WASHINGTON DC PLASMA PHYSICS DIV
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| Electron Energy Deposition in an E-Beam Pumped KrF Amplifier: Impact of Beam Power and Energy |
23 DEC 2002 |
57 pages |
| Authors:
G. M. Petrov; J. L. Giuliani; A. DASGUPTA; BERKELEY SCHOLARS INC SPRINGFIELD VA
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| Collective Motional Resonances and Instabilities of an Electron Cloud Stored in a Penning Trap |
24 JUN 2002 |
6 pages |
| Authors:
D. Biswas; P. Paasche; T. Valenzuela; C. Angelescu; S. Ananthamurthy; BANGALORE UNIV (INDIA) DEPT OF PHYSICS
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| We have experimentally investigated the behaviour of an electron cloud confined in a Penning trap at weak superimposed magnetic fields. Exciting the motional frequencies of the electrons by an external drive field we found the axial mode split into two components which were identified as center-of-mass and individual electron oscillations. When the trapping potential was varied. rapid electron loss appeared at numerous values of the applied voltage. They are determined ... |
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| Investigation of the Expansion Rate Scaling of Plasmas in the Electron Diffusion Gauge Experiment |
24 JUN 2002 |
6 pages |
| Authors:
Kyle A. Morrison; Ronald C. Davidson; Stephen F. Paul; Thomas G. Jenkins; PRINCETON UNIV NJ PLASMA PHYSICS LAB
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| The expansion of the Electron Diffusion Gauge(EDG) pure electron plasma due to collisions with background neutral gas atoms is characterized by the pressure and magnetic field scaling of the profile expansion rate (d/dt) (r squared). Data obtained at higher background gas pressures than previously studied is presented. The measured expansion rate in the higher pressure regime is found to be in good agreement with the classical estimate of the expansion ... |
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| Nonlinear PIC Simulation in a Penning Trap |
24 JUN 2002 |
10 pages |
| Authors:
G. Lapenta; G. L. Delzanno; J. M. Finn; LOS ALAMOS NATIONAL LAB NM
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| We study the nonlinear dynamics of a Penning trap plasma, including the effect of the finite length and end curvature of the plasma column. A new cylindrical PIC code, called KANDINSKY, has been implemented by using a new interpolation scheme. The principal idea is to calculate the volume of each cell from a particle volume, in the same manner as it is done for the cell charge. With this new ... |
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| Energy Loss of Ions by Collisions with Magnetized Electrons |
24 JUN 2002 |
10 pages |
| Authors:
G. Zwicknagel; C. Toepffer; ERLANGEN-NUERNBERG UNIV (GERMANY F R)
|
| The interaction of ions with electrons in the presence of an external magnetic field is a basic process for the description of the transport properties of a magnetized plasma, as e.g. the energy loss of ions to the superimposed electron beam in the electron cooler of a storage ring. But a comprehensive description of binary collisions of ions and electrons in the presence an external magnetic field has still to ... |
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| Flowing Electron Plasmas as Modified Current Source |
24 JUN 2002 |
10 pages |
| Authors:
Haruhiko Himura; Chihiro Nakashima; Haruhiko Saito; Zensho Yoshida; Junji Morikawa; TOKYO UNIV (JAPAN) GRADUATE SCHOOL OF FRONTIER SCIENCES
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| Probing of streaming electron plasmas with finite temperature is studied. Due to the fast flow of the electron plasmas, the characteristic curve spreads out significantly and exhibits a long tail. Another significant feature of the characteristic is that it determines a floating potential where the current equals zero, despite there being very few ions in the electron plasma. A high impedance probe, which is popularly used to determine the space ... |
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| Ion Density Fluctuations in Plasma and Their Effects on Hot Electron Generation |
JUN 2002 |
61 pages |
| Authors:
Marty Wallace; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| In this thesis, high-energy electron generation by stimulated Raman scattering of intense laser light is investigated in computer simulations. These high-energy electrons can be used to produce a high-energy x-ray source for Nuclear Weapons Effects Testing. The simulation results are compared with actual experiments conducted at the Atomic Weapons Establishment in the United Kingdom. The simulations show that the heated electron temperature is significantly lowered and the frequency spectrum of ... |
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| A New System of Parallel Isolated Nonthermal Filaments Near the Galactic Center: Evidence for a Local Magnetic Field Gradient |
14 AUG 2001 |
10 pages |
| Authors:
T. N. LaRosa; T. J. Lazio; Namir E. Kassim; KENNESAW STATE UNIV GEORGIA DEPARTMENT OF BIOLOGICAL AND PHYSICAL SCIENCES
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| We report the discovery of a system of isolated nonthermal filaments approximately northwest 0 degrees.5 (75 pc in projection) of Sgr A. Unlike other isolated nonthermal filaments which show subfilamentation, braiding of subfilaments, and flaring at their ends, these filaments are simple linear structures and more closely resemble the parallel bundled filaments in the Galactic center radio arc. However, the most unusual feature of these filaments is that the 20/90 ... |
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| Advanced Applications for 0.53 micrometers Laser Light |
JUN 2001 |
70 pages |
| Authors:
W. D. Jones; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| Use of the National Ignition Facility with green light as the laser output is an intriguing option for advanced applications ranging from inertial fusion to production of compact x-ray sources. Particular attention is given to the potential use of 0.53 micrometers light to produce a high-energy x-ray source. This application requires the efficient generation of high-energy electrons which can subsequently produce high-energy x-rays as they transport into gold or other ... |
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| Free Electron Laser Development for Directed Energy |
DEC 2000 |
150 pages |
| Authors:
Roger D. McGinnis; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| This dissertation investigates power requirements for a Free Electron Laser to burn through various missile radome materials. It also includes computer simulation results for several FEL system configurations designed to achieve maximum power while maintaining strict energy spread constraints. The method used to determine power requirements to burn through materials was to use the Thomas Jefferson National Accelerator Facility's Free Electron Laser to conduct material damage experiments. As the laser ... |
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| Electron Energy Levels in Magnetic Nanoparticles |
01 AUG 2000 |
8 pages |
| Authors:
Daniel C. Ralph; CORNELL UNIV ITHACA NY LAB OF ATOMIC AND SOLID STATE PHYSICS
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| Final Report for Grant #N00014-97-1-0745. Progress is reported on (a) investigations of electron tunneling via individual "electron-in-a-box" quantum energy levels in magnetic nanoparticles, and the sensitivity of these energy levels to changes in the orientation of the particle's magnetic moment, and (b) a discovery that spin-polarized currents in magnetic multilayer samples can be used to controllably switch the orientation of magnetic layers, due to an ... |
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| Selected Energy Epitaxial Deposition and Low Energy Electron Microscopy of AlN, GaN and SiC Thin Films |
DEC 1998 |
23 pages |
| Authors:
R. F. Davis; H. H. Lamb; I. S. Tsong; NORTH CAROLINA STATE UNIV AT RALEIGH DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| In situ real-time low energy electron microscopy of GaN homoepitaxial growth using supersonic jets was conducted. Non-faceted basal-plane GaN(0001) layers were successfully grown when the GaN/NH3 flux ratios exceeded two in the temperature range of 660-710 deg C. Very smooth layers with atomic steps were obtained when growth occurred on regions of the substrate surface previously covered by Ga liquid droplets. This effect is believed to be due to the ... |
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| Electron Energy Levels in Magnetic Nanoparticles |
30 APR 98 |
6 pages |
| Authors:
Daniel C. Ralph; CORNELL UNIV ITHACA NY LAB OF ATOMIC AND SOLID STATE PHYSICS
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| Annual progress report for N00014-97-1-0745. We provide details concerning equipment installation, start-up experiments on effects of spin-orbit scattering impurities on the superconducting properties of aluminum nanoparticles, and efforts to optimize procedures for making nm-scale tunnel barriers on magnetic electrodes. |
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| Selected Energy Epitaxial Deposition and Low Energy Electron Microscopy of AlN, GaN and SiC Thin Films |
MAR 96 |
24 pages |
| Authors:
R. F. Davis; H. H. Lamb; I. S. Tsong; NORTH CAROLINA STATE UNIV AT RALEIGH
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| Gallium nitride has been deposited using hyperthermal and thermal beams of NH3 and triethylgallium seeded in He and Ar supersonic jets, respectively. The V/III ratio = 344. The growth rates were lower and the film character poor when Ar was used as the carrier. The films deposited using He were continuous and adherent and exhibited a characteristic wavy surface morphology. The major components of a new SEED facility have been ... |
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| Characterization of the Energy Deposition Produced by the Primary Electron Beam on the Excede III Program |
MAY 93 |
38 pages |
| Authors:
R. J. Rieder; R. L. McNutt; S. A. Rappaport; VISIDYNE INC BURLINGTON MA
|
| The primary goal of the EXCEDE III (Excitation by Electron Deposition) atmospheric energy deposition experiment was to monitor the spatial distribution of the energy deposition profile produced by the approx. 18 Ampere approx. 2.5 keV electron beam. During the rocket flight on April 27, 1 990, prompt emission at 391 4 A from the N sub2 + (1N) 0-0 transition were measured by a UV scanning photometer. We have inverted ... |
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| A Derivation of the Topside Heat Flux Using Incoherent Scatter Radar Observations |
JUN 92 |
213 pages |
| Authors:
Devin J. Della-Rose; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
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| Analysis of Dynamical Plasma Interactions with High-Voltage Spacecraft |
JUN 92 |
183 pages |
| Authors:
M. J. Mandell; T. Luu; J. Lilley; G. Jongeward; I. Katz; S-CUBED LA JOLLA CA
|
| This volume describes numerous plasma interaction problems done in support of DynaPAC code development, and in support of the SPEAR-II and SPEAR-3 programs. Two dimensional calculations show that oscillations of a beam emitted into an underdense plasma can cause overcharging of a beam emitting rocket, as was observed on MAIMIK. The effects of the sheath instability caused by orbital motion of a positive body are studied, showing that substantial potential ... |
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| Collisional Relaxation of Non-Maxwellian Plasma Distribution in a Polywell (Tradename) |
JUN 92 |
46 pages |
| Authors:
M. Rosenberg; Nicholas A. Krall; DIRECTED TECHNOLOGIES INC ARLINGTON VA
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| The Polywell is a magnetic version of a Spherically Convergent Ion Focus (SCIF) device which was proposed as a significant variation of earlier studies on electrostatic confinement. The idea of this device is to inject high energy electrons into a quasi-spherical magnetic field; the electrons create a potential well of sufficient depth to accelerate ions from low energy at the periphery to fusion energies within a focus at the center ... |
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| Electron Recirculation in Electrostatic Multicusp Systems: 1. Confinement and Losses in Simple Power Law Wells |
19 APR 91 |
55 pages |
| Authors:
Robert W. Bussard; Katherine E. King; DIRECTED TECHNOLOGIES INC ARLINGTON VA
|
| A large body of work over the past 35 years has been devoted to the study of cusp confinement of electrons, ions, and plasmas. Nearly all of this has examined single particle electron (or ion) motion or the motion of particles in neutral plasmas within cusped magnetic systems, generally without internal electric potential fields. In this note the problem of electron motion, confinement and losses is analyzed in the non-LTE, ... |
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| Elucidation of Heterogeneous Processes Controlling Boost Phase Signatures |
12 SEP 90 |
10 pages |
| Authors:
Pazhayannur K. Swaminathan; CHEMICAL DYNAMICS CORP UPPER MARLBORO MD
|
| This final report summarizes work carried out in a three year research program to develop efficient theoretical methods to study collisional processes involved in radiative signature modeling. The problems of rotational, vibrational and electronic energy transfer have been studied using novel semiclassical methods. The developed advancements in techniques are generally applicable to a state-to-state description of gas phase and gas/surface collisions leading to radiating species. Keywords: Boost phase signatures, Gas ... |
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| Monte-Carlo Simulations of Gas Discharge Systems with Some Application to SF6 |
AUG 90 |
18 pages |
| Authors:
P. K. Milsom; ROYAL SIGNALS AND RADAR ESTABLISHMENT MALVERN (UNITED KINGDOM)
|
| The Monte Carlo method is used to consider the behaviour of an electron swarm released into a Sulphur HexaFluoride gas discharge. The mean energy of the swarm is monitored as a function of time and when the steady state is reached the energy and velocity distributions are calculated. The growth in electron number is also monitored and this is used to determine the stable working field in the gas. The ... |
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| The Application of HREELS to Model Catalysts: CO and C2H4 Adsorption on Pt/Al2O3 |
20 MAY 90 |
27 pages |
| Authors:
D. A. Hensley; L. L. Kesmodel; INDIANA UNIV AT BLOOMINGTON DEPT OF PHYSICS
|
| A model catalyst made by platinum vapor deposition onto a thin alumina film is investigated with Transmission Electron Microscopy and High Resolution Electron Energy Loss Spectroscopy. The preparation techniques are fully described, then the results of TEM analysis for platinum deposits from 0.3 monolayers to 1.7 monolayers are reported, for which clusters varying from 1.0 to 1.6 nanometers in diameter are observed. High Resolution Electron Energy Loss Spectroscopy spectra are ... |
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| High Resolution Electron Energy Loss Spectroscopy Studies of Chemisorbed Species on Metal Surfaces |
31 MAR 90 |
14 pages |
| Authors:
J. L. Erskine; TEXAS UNIV AT AUSTIN DEPT OF PHYSICS
|
| The objective of this research program is to utilize high resolution electron energy loss spectroscopy and other spectroscopic tools to investigate chemical and physical properties of surfaces and of gas-surface interactions. Our experiments address issues pertaining to bond lengths and site symmetry of chemisorbed atoms and molecules at metal surfaces, binding energies and vibrational frequencies associated with the atomic and molecular bonds, and with the driving mechanisms responsible for structural ... |
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| Production Rates for Electron Beams and Swarms in Nitrogen |
24 FEB 90 |
24 pages |
| Authors:
S. P. Slinker; A. W. Ali; R. D. Taylor; NAVAL RESEARCH LAB WASHINGTON DC
|
| Detailed calculations of the deposition of electron energy in molecular nitrogen are presented. Two cases are considered. In the first one, the electrons are accelerated by a constant, uniform electric field as in a swarm experiment. The reduced electric field strength ranges from 1 to 300 Townsends. In the second case, deposition is initiated by electron beams with energies up to 10 MeV. Production rates for the various excitation channels ... |
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| Scanning Electron Microscopy by Photovoltage Contrast Imaging. |
20 FEB 1990 |
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| Authors:
Larry D. Flesner; DEPARTMENT OF THE NAVY WASHINGTON DC
|
 | A process and apparatus are disclosed for remotely determining electrical properties of a semiconductor. A surface of the semiconductor is simultaneously irradiated with an electron beam to generate secondary electrons from the irradiated surface and with a modulated light beam. Secondary electrons emitted by the semiconductor are filtered by an electron energy analyzer. An electron detector receives the filtered electrons and provides an output corresponding to electrical properties of the ... |
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| Electronic Energies for Neon Dimer Dication Radiative Charge Transfer |
DEC 89 |
66 pages |
| Authors:
Roger A. Deemer; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING
|
| This research was conducted to find the shape of the potential energy surfaces for the Neon dimer dication, designated Ne2(+2), to include all symmetries which dissociate to two ground state Ne(+) ions or a ground state Ne atom and Ne(+2) ion. The motivation is to investigate whether there is a minimum in the upper level, the Ne(+2) and Ne level, located in such a way that populations of bound dimer ... |
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| Physics of High Energy Photoconductive Switches |
JUN 89 |
25 pages |
| Authors:
Erich E. Kunhardt; POLYTECHNIC UNIV FARMINGDALE NY WEBER RESEARCH INST
|
| During this funding period, a semi-classical macro-kinetic theory that describes the dynamic behavior of carriers in a semiconductor under the influence of space-time varying fields has been formulated. The macro-kinetic model is considerably easier to implement numerically than Monte Carlo methods or those based on the Boltzmann Transport Equation (BTE). Moreover, the macro- kinetic model requires orders of magnitude less computer time to run. A Monte Carlo method has been ... |
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| Electron Energy Levels in a Quantum Well within an In-Plane Magnetic Field |
JUN 89 |
23 pages |
| Authors:
H. R. Lee; H. G. Oh; Thomas F. George; C. I. Um; STATE UNIV OF NEW YORK AT BUFFALO DEPT OF CHEMISTRY
|
| The exact eigenenergy spectrum of an electron is calculated in a quantum well within an in-plane magnetic field. The numerical solutions for the excited energy states as well as the ground state energy are found for various quantum-well widths and barrier heights. The cyclotron orbits are considerably affected by the quantum well. The energy levels higher than the potential height of the quantum well and the energy levels lower than ... |
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| Production of Very Energetic Electrons in a Discrete Aurora |
26 APR 89 |
21 pages |
| Authors:
D. W. Swift; D. J. Gorney; AEROSPACE CORP EL SEGUNDO CA LAB OPERATIONS
|
| Data are presented showing that acceleration of electrons to energies in excess of 100 keV sometimes occurs on field lines associated with discrete auroral arcs. Velocity distributions suggest that acceleration is in directions primarily perpendicular to the magnetic field. The examples studied in the S3-3 data set indicate that the process can occur in the altitude range from the topside ionosphere to 5500 km. Our favored explanation is that the ... |
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| Time-Resolved Surface Structural Study by Picosecond Reflection High- Energy Electron Diffraction |
21 MAR 89 |
56 pages |
| Authors:
Hani E. Elsayed; ROCHESTER UNIV N Y LAB FOR LASER ENERGETICS
|
| The objective of this program was to develop an instrument for characterization of nanosecond and picosecond time evolution of surface properties. This instrument was developed based on the technique of picosecond time-resolved reflection high-energy electron diffraction (RHEED). The basic idea of this technique is the utilization of 150 ps laser pulses to generate electron pulses by the photoelectric effect. The photogenerated electrons are accelerated, focused, and collimated using electron optics. ... |
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| Theory of Electronic States and Formation Energies of Defect Complexes, Interstitial Defects and Crystal Growth in Semiconductors |
89 |
17 pages |
| Authors:
Otto F. Sankey; ARIZONA STATE UNIV TEMPE DEPT OF PHYSICS
|
| Briefly summarized is all the work that has been performed in this final report. The major accomplishments were (i) the determination of trends in defect concentration in III-V and II-VI semiconductors, and (ii) the development and deployment of a novel quantum molecular dynamics method which is far faster and can handle larger systems than any competing method. These topics will be marked with a **** to indicate their importance. The ... |
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| International Symposium on Dissociative Recombination: Theory, Experiment and Applications Held in Lake Louise, Alberta on 28 - 31 May 1988 |
30 NOV 88 |
|
| Authors:
J. B. Mitchell; UNIVERSITY OF WESTERN ONTARIO LONDON DEPT OF PHYSICS
|
| This report contains a summary of the papers presented at the International Symposium on Dissociative Recombination: Theory, Experiment and Applications held at Lake Louise, Alberta, Canada. May 28-31, 1988. Dissociative recombination (DR) of molecular ions with electrons has important consequences in many areas of physical science. Theory: The proposed mechanism was several years in the making because it had to overcome two important obstacles. First, due to the mass mismatch, ... |
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| A New Procedure for Determination of Electron Temperatures and Electron Concentrations by Thomson Scattering and Analytical Plasmas |
28 OCT 88 |
41 pages |
| Authors:
Huang Mao; Gary M. Hieftje; INDIANA UNIV AT BLOOMINGTON DEPT OF CHEMISTRY
|
| A new data-treatment procedure allows for more accurate determination of electron temperatures and electron concentrations in analytical plasmas. A thomson scattering spectrum, useful for these determinations, is often not purely Gaussian in shape, even when the probed electrons possess a Maxwellian velocity distribution. Nonetheless, an unambiguous relationship exists between electron temperatures and concentrations that truly exist in a plasma and those calculated from a distorted Thompson scattering spectrum. Understanding this ... |
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| Chaotic Electron Motion Caused by Sidebands in Free Electron Lasers |
27 OCT 88 |
86 pages |
| Authors:
S. Riyopoulos; C. M. Tang; NAVAL RESEARCH LAB WASHINGTON DC
|
| The electron dynamics in a Free Electron Laser (FEL) is studied in the case when the radiation field contains many modes. This situation arises when unstable modes (sidebands) are excited during operation. It is observed that when the strength of these sidebands exceeds certain levels, The electron motion becomes chaotic. This may lead to extensive particle detrapping and loss of amplification for the FEL signal. The threshold for the onset ... |
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| Outer Zone Electron Precipitation Produced by a VLF Transmitter |
01 MAR 88 |
|
| Authors:
Alfred L. Vampola; C. D. Adams; AEROSPACE CORP EL SEGUNDO CA SPACE SCIENCES LAB
|
| Using high resolution pitch angle measurements made by a magnetic focusing electron spectrometer on the S3-3 satellite while in the drift loss cone region of the magnetosphere, characteristics of fluxes of 108 keV to 654 keV electrons precipitated in the inner zone, in the slot region, and in the outer zone of the magnetosphere are all shown to be consistent with the precipitation having been produced by the same ground-based ... |
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| Thomson Scattering for Determining Electron Concentrations and Temperatures in an Inductively Coupled Plasma. 1. Assessment of the Technique for a Lo -Flow, Low-Power Plasma |
15 FEB 88 |
|
| Authors:
Kim A. Marshall; Gary M. Hieftie; INDIANA UNIV AT BLOOMINGTON DEPT OF CHEMISTRY
|
| Electron number densities and electron temperatures have been measured by multichannel Thomson scattering in a low-flow low-power inductively coupled plasma. Preliminary electron-concentration values agree well with those previously determined, and spatial variation in both electron concentration and temperature are largely consistent with existing models of the ICP. One difference is that aqueous aerosol was found here to depress the electron number density throughout the plasma. Unfortunately, the intensities measured in ... |
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| Laboratory Studies of Atomic Collision Processes |
26 FEB 87 |
|
| Authors:
R. Johnsen; M. A. Biondi; PITTSBURGH UNIV PA DEPT OF PHYSICS
|
| Accomplishments: Dissociative recombination of O4(+) ions with electrons as a function of electron temperature. Development of computer codes to describe electron-energy gain and loss processes in plasmas heated by microwaves, including effects of inelastic collisions with molecules and spatially non uniform fields. Development of the rf conductivity method to determine electron and ion densities in plasmas at atmospheric neutral densities. Development of mass spectrometric techniques to analyze the ion composition ... |
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| Electron Acceleration by Wave Processes in the Earth's Ionosphere |
31 DEC 86 |
|
| Authors:
G. J. Morales; J. E. Maggs; CALIFORNIA UNIV LOS ANGELES DEPT OF PHYSICS
|
| The nonlinear modification of the electron distribution function caused by the interaction with a resonant electrostatic field is studied analytically using a perturbation analysis. This interaction produces tail heating and for a limited range of parameter values can form a bump in the distribution, which may lead to emission of secondary waves. These results are applied to the ionosphere's F and upper E regions in the context of ionospheric modification ... |
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| Electron Energy Deposition in Atomic Oxygen |
31 DEC 86 |
|
| Authors:
S. Slinker; A. W. Ali; NAVAL RESEARCH LAB WASHINGTON DC
|
| The interaction of high energy electrons with atomic oxygen is described. A code for discrete energy deposition scheme was developed. The discrete energy method provides the electron loss function in oxygen the secondary electron distribution, the mean energy per electron-ion pair generation, and the efficiencies of all relevant inelastic processes. Our calculations show that energy electrons (500-100,000 eV) expend approx. 28 eV to generate an electron-ion pair. |
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*ELECTRON ENERGY
