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Stable Equilibrium Statistical States For Spheromaks, George Vahala, Linda L. Vahala Jan 1979

Stable Equilibrium Statistical States For Spheromaks, George Vahala, Linda L. Vahala

Electrical & Computer Engineering Faculty Publications

Incompressible nondissipative magnetohydrodynamic turbulence is treated for spherical systems. From the absolute equilibrium expectation values of the fields one can investigate those initially quiescent states for which no large mean square velocity will develop. This stable state is force-free and gives rise to the Hill vortex structure for the magnetic flux surfaces.

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Nonlinear Anelasticity And The Martensitic Transformation, Manfred Wuttig, Tetsuro Suzuki Jan 1979

Nonlinear Anelasticity And The Martensitic Transformation, Manfred Wuttig, Tetsuro Suzuki

Materials Science and Engineering Faculty Research & Creative Works

Zener's model of a standard linear solid is extended to include nonlinearities characteristic of metals and alloys in the vicinity of a martensitic transformation. The equation of motion of a nonlinear anelastic solid is derived and solved using van der Pol's method. The characteristics of the solutions indicate that auto-oscillations of finite amplitude can be excited externally. It is proposed that the streaming oscillations represent the beat between the external excitation and the auto-oscillation. © 1979.

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Nucleation Experiments With Monodisperse Nacl Aerosols., Darryl J. Alofs, M. B. Trueblood, D. R. White, V. L. Behr Jan 1979

Nucleation Experiments With Monodisperse Nacl Aerosols., Darryl J. Alofs, M. B. Trueblood, D. R. White, V. L. Behr

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Nucleation Experiments with Monodisperse NaCl Aerosols Showed Good Agreement with the Kohler Theory Relating the Critical Super-Saturation S//c to the Dry Size. Aerosols Produced by Condensing NaCl Showed the Same S//c as Those Produced by Evaporating Aqueous NaCl Solution Droplets. This Indicates that If There is an Energy Barrier in Going from a Dry NaCl Particle to a Solution Droplet, This Energy Barrier is Small. the Fact that the Evaporation Aerosol Particles Are Cubical Crystals and the Condensation Aerosols Are Amorphous Spheres is Shown to Make No Difference in the Nucleation Threshold. the Investigation Also Gives Insights into the Performance …

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Negative Ion Production Rates In Rare Gas-Halide Lasers, Kaare J. Nygaard, Howard L. Brooks, Scott R. Hunter Jan 1979

Negative Ion Production Rates In Rare Gas-Halide Lasers, Kaare J. Nygaard, Howard L. Brooks, Scott R. Hunter

Physics Faculty Research & Creative Works

This paper reports on dissociative electron attachment in F2, NF3, Cl2, and I2. The principle of the method is to produce a short burst of photoelectrons from a photocathode by means of light from an argon-fluoride laser. Subsequently, by studying the motion of electrons and negative ions in a constant electric field (E) region, information is obtained about drift velocities and effective attachment cross sections. Helium, argon, and nitrogen were used as buffer gases. Of particular interest is a very strong temperature dependence of the attachment coefficient in I2. Measurements were taken from 35 to 110°C, covering an E/N range …

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Precision Doubly Differential Cross Section Measurements, John T. Park Jan 1979

Precision Doubly Differential Cross Section Measurements, John T. Park

Physics Faculty Research & Creative Works

Ion Energy Loss Spectrometry has been applied to the measurement of cross sections differential in both scattering angle and ion energy loss. Differential cross sections obtained for excitation of the n=2 level of atomic hydrogen by various ions provides unexpectedly good agreement with the available theories. Copyright © 1978 by The Institute of Electrical and Electronics Engineers, Inc.

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Temperature Dependence Of The Electron Attachment Coefficient In Iodine, Howard L. Brooks, Scott R. Hunter, Kaare J. Nygaard Jan 1979

Temperature Dependence Of The Electron Attachment Coefficient In Iodine, Howard L. Brooks, Scott R. Hunter, Kaare J. Nygaard

Physics Faculty Research & Creative Works

The attachment coefficient for iodine in a (1% I2+99% N 2) mixture, 50 Torr total pressure, has been measured in an electron swarm experiment from 1 to 50 Townsends (1 Townsend=1Td=10-17 V cm2). As the temperature was increased from 35 to 110°C, the attachment coefficient increased for any E/N (electric field intensity/gas number density) values greater than 7 Td. These results are compared to other experimental data and an explanation for the temperature dependence, based on the population of upper vibrational states, is presented. © 1979 American Institute of Physics.

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A Feasibility Study Concerning The Use Of Alternate Energy Sources In Taiwan, Li-Juan Lee Dec 1978

A Feasibility Study Concerning The Use Of Alternate Energy Sources In Taiwan, Li-Juan Lee

Masters Theses

No abstract provided.

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Principal Angle, Principal Azimuth, And Principal-Angle Ellipsometry Of Film-Substrate Systems, R. M.A. Azzam, A.-R. M. Zaghloul Dec 1978

Principal Angle, Principal Azimuth, And Principal-Angle Ellipsometry Of Film-Substrate Systems, R. M.A. Azzam, A.-R. M. Zaghloul

Electrical Engineering Faculty Publications

When the film thickness is considered as a parameter, a system composed of a transparent film on an absorbing substrate (in a transparent ambient) is characterized by a range of principal angle ø¯min ≤ ø¯ ≤ ø¯max over which the associated principal azimuth ψ¯ varies between 0° and 90° (i.e., 0° ≤ ψ¯ ≤ 90°) and the reflection phase difference Δ assumes either one of the two values: +π/2 or −π/2. We determine the principal angle ø¯(d) and principal azimuth ψ¯(d) as functions of film thickness d for the vacuum-SiO2-Si system at …

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Propagation Of Partially Polarized Light Through Anisotropic Media With Or Without Depolarization: A Differential 4 × 4 Matrix Calculus, R. M.A. Azzam Dec 1978

Propagation Of Partially Polarized Light Through Anisotropic Media With Or Without Depolarization: A Differential 4 × 4 Matrix Calculus, R. M.A. Azzam

Electrical Engineering Faculty Publications

We extend the scope of the Mueller calculus to parallel that established by Jones for his calculus. We find that the Stokes vector S of a light beam that propagates through a linear depolarizing anisotropic medium obeys the first-order linear differential equation dS/dz = mS, where z is the distance traveled along the direction of propagation and m is a 4 × 4 real matrix that summarizes the optical properties of the medium which influence the Stokes vector. We determine the differential matrix m for eight basic types of optical behavior, find its form for the most general anisotropic nondepolarizing …

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Nmr Instrumentation With Solid State Devices, Syed M. Ahmed Dec 1978

Nmr Instrumentation With Solid State Devices, Syed M. Ahmed

Masters Theses

No abstract provided.

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Chemical Vapor Deposited Amorphous Silicon For Use In Photothermal Conversion, David D. Allred, D. C. Booth, M. Janai, G. Weiser, B. O. Seraphin Nov 1978

Chemical Vapor Deposited Amorphous Silicon For Use In Photothermal Conversion, David D. Allred, D. C. Booth, M. Janai, G. Weiser, B. O. Seraphin

Faculty Publications

Efficient photothermal conversion requires surfaces of high solar absorptance and low thermal emittance. This can be accomplished by the tandem action of a good infrared reflector overlaid by a film of sufficient solar absorptance that is transparent in the infrared. Crystalline silicon is a suitable candidate for the absorber layer. Its indirect band gap, however, results in a shallow absorption edge that extends to far into the visible. In contrast, the absorption edge of amorphous silicon is steeper and located farther into the infrared, resulting in a larger solar absorptance. We report on the fabrication of amorphous silicon absorbers by …

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Chemical Vapor Deposited Molybdenum Films For Use In Photothermal Conversion, David D. Allred, G. E. Carver, B. O. Seraphin Nov 1978

Chemical Vapor Deposited Molybdenum Films For Use In Photothermal Conversion, David D. Allred, G. E. Carver, B. O. Seraphin

Faculty Publications

High infrared reflectance, coupled with higher solar absorptance, is required for efficient photothermal conversion. Converters can be fabricated by depositing an absorber on a highly reflecting metal. The absorber functions in the visible, yet becomes transparent in the near infrared, allowing the metal to suppress the thermal emittance. Economic considerations demand the use of thin films, rather than bulk materials. The thin film reflector must be capable of withstanding high temperatures of operation. Compatibility of the reflector with the substrate below, and the absorber above, is required for long-time service. Highly reflective silver films suffer reflectance losses by agglomeration, and …

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Consequences Of Light Reflection At The Interface Between Two Transparent Media Such That The Angle Of Refraction Is 45°, R. M.A. Azzam Nov 1978

Consequences Of Light Reflection At The Interface Between Two Transparent Media Such That The Angle Of Refraction Is 45°, R. M.A. Azzam

Electrical Engineering Faculty Publications

The reflection of light at the interface between two transparent, homogeneous and optically isotropic media such that the angle of refraction is 45° has the following interesting consequences: (i) the interface relfectivity for the parallel (p) polarization is the square of that for the perpendicular (s) polarization; (ii) the angular deviation of the propagation direction upon refraction is equal to the polarization (or ellipsometric) angle ψ and (iii) the complex reflection coefficient for the ppolarization is stationary, in both magnitude and phase, with respect to small charges of the (refractive and/or absorptive) optical properties of …

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20th Annual Rocky Mountain Conference On Analytical Chemistry Aug 1978

20th Annual Rocky Mountain Conference On Analytical Chemistry

Rocky Mountain Conference on Magnetic Resonance

Abstracts and program from the 20th annual meeting of the Rocky Mountain Conference on Analytical Chemistry, co-sponsored by the Rocky Mountain Section of the Society for Applied Spectroscopy and the Rocky Mountain Chromatography Discussion Group. Held in Denver, Colorado, August 7-9, 1978.

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Simulation Of Mechanical Rotation By Optical Rotation: Application To The Design Of A New Fourier Photopolarimeter, R. M.A. Azzam Apr 1978

Simulation Of Mechanical Rotation By Optical Rotation: Application To The Design Of A New Fourier Photopolarimeter, R. M.A. Azzam

Electrical Engineering Faculty Publications

The mechanical rotation of an optical element around the axis of a beam of polarized light can be easily simulated by using the phenomenon of optical rotation. Because optical rotation can be magnetically or electrically induced, virtually any kind of mechanical rotation can be mimicked. This interesting principle is applied to the design of a new Fourier photopolarimeter that uses an oscillating-azimuth retarder (OAR). The OAR consists of a quarter-wave plate surrounded by two ac-excited Faraday cells that produce equal and opposite sinusoidal optical rotations. Analysis of the operation of this polarimeter of no moving parts proves its ability to …

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Generalized Ellipsometry Based On Azimuth Measurements Alone, R. M.A. Azzam Apr 1978

Generalized Ellipsometry Based On Azimuth Measurements Alone, R. M.A. Azzam

Electrical Engineering Faculty Publications

We investigate the azimuth response function, θo = f(θi), of a linear nondepolarizing optical system S, whereθi and θo, are the azimuths (orientations) of the generally elliptic vibrations of totally polarized light at the input and output of S. We find that the azimuth response function depends on five of the six parameters that specify the normalized circular Jones matrix of the optical system. Thus the entire polarization response of an optical system can be nearly completely reconstructed from its azimuth response alone. Five input-output azimuth measurements (θik, θok), k …

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The Stephen F. Austin Traveling Science Show, James C. Dennis Jan 1978

The Stephen F. Austin Traveling Science Show, James C. Dennis

Faculty Publications

No abstract provided.

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Two-Step Photoionization Of Potassium Atoms, Kaare J. Nygaard, Robert J. Corbin, James A. Jones Jan 1978

Two-Step Photoionization Of Potassium Atoms, Kaare J. Nygaard, Robert J. Corbin, James A. Jones

Physics Faculty Research & Creative Works

The cross section for photoionization of potassium atoms in the 4P2 states has been measured in a triple-crossed-beam experiment. © 1978 The American Physical Society.

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A Xenon Ion Pumped Blue Dye Laser, D. W. Fahey, Laird D. Schearer Jan 1978

A Xenon Ion Pumped Blue Dye Laser, D. W. Fahey, Laird D. Schearer

Physics Faculty Research & Creative Works

A pulsed xenon ion laser with an output power of 5 kW at 364.5 nm has been used as a pump source for several blue dyes. Broadband conversion efficiencies exceed 20 percent. The use of a birefringent filter provides tunable output in the blue region of the spectrum with a bandwidth of 0.08 nm and a pulse width of 120 ns. © 1978 IEEE

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The Coma/A1367 Supercluster And Its Environs, Stephen A. Gregory, Laird A. Thompson Jan 1978

The Coma/A1367 Supercluster And Its Environs, Stephen A. Gregory, Laird A. Thompson

Department of Physics and Astronomy: Faculty Publications

The three-dimensional galaxy distribution in the region of space surrounding the two rich clusters Coma and A1367 is analyzed by using a nearly complete redshift sample of 238 galaxies with mp < 15.0 in a 260 degree2 region of the sky; 44 of these redshifts are reported here for the first time. We find that the two clusters are enveloped in a common supercluster which also contains four groups and a population of isolated galaxies. The least dense portions of the Coma/A1367 supercluster have a density which is approximately 6 times that of the Local Supercluster in the regions of our own Galaxy. In …

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Studies Of The Temporary Anion States Of Unsaturated Hydrocarbons By Electron Transmission Spectroscopy, Kenneth D. Jordan, Paul Burrow Jan 1978

Studies Of The Temporary Anion States Of Unsaturated Hydrocarbons By Electron Transmission Spectroscopy, Kenneth D. Jordan, Paul Burrow

Paul Burrow Publications

The concept of occupied and unoccupied orbitals has provided a useful means for visualizing many of the most important properties of molecular systems. Yet, there is a curious imbalance in our experimental knowledge of the energies of occupied and unoccupied orbitals. Whereas photoelectron spectroscopy has provided a wealth of data on positive ion states and has established that they can be associated, within the context of Koopmans’ theorem, with the occupied orbitals of the neutral molecule, the corresponding information for the negative ion states, associated with the normally unoccupied orbitals, is sparse. In part this reflects the experimental difficulties connected …

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The Electrical Characterization Of Semi‐Insulating Gaas: A Correlation With Mass‐Spectrographic Analysis, David C. Look Dec 1977

The Electrical Characterization Of Semi‐Insulating Gaas: A Correlation With Mass‐Spectrographic Analysis, David C. Look

Physics Faculty Publications

The room‐temperature electrical properties of 28 semi‐insulating GaAs crystals have been determined by using a mixed‐conductivity analysis. It is shown that for most of these samples, such an analysis gives good accuracy for the electron mobility μn and electron concentration n, but poorer accuracy for the hole mobility μp, hole concentration p, and intrinsic concentration ni. The intrinsic concentration is determined at 296 °K to be ni ≈ (1.7±0.4) ×106 cm−3, which compares favorably with the theoretical value deduced from the band gap and the effective masses. From a …

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Single-Element Rotating-Polarizer Ellipsometer For Film-Substrate Systems, A.-R. M. Zaghloul, R. M.A. Azzam Sep 1977

Single-Element Rotating-Polarizer Ellipsometer For Film-Substrate Systems, A.-R. M. Zaghloul, R. M.A. Azzam

Electrical Engineering Faculty Publications

A novel and very simple ellipsometer for the characterization of film-substrate systems that employs one rotating optical element (a polarizer) is proposed. The ellipsometer is based on detecting the angles of incidence at which a film-substrate system has equal amplitude attenuations for light polarized parallel (p) and perpendicular (s) to the plane of incidence. At a certain wavelength, the film thickness of the filmsubstrate system has to lie within permissible-thickness bands (PTB) for the technique to apply.

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The Use Of Nuclear Reactions And Sims For Quantitative Depth Profiling Of Hydrogen In Amorphous Silicon, David D. Allred, G. J. Clark, C. W. White, B. R. Appleton, C. W. Magee, D. E. Carlson Aug 1977

The Use Of Nuclear Reactions And Sims For Quantitative Depth Profiling Of Hydrogen In Amorphous Silicon, David D. Allred, G. J. Clark, C. W. White, B. R. Appleton, C. W. Magee, D. E. Carlson

Faculty Publications

Depth profiles for hydrogen in amorphous silicon have been determined by the use of resonant nuclear reactions [1H(15N,αγ)12C and 1H(19F,αγ)16O] and by secondary ion mass spectroscopy (SIMS). Independent calibration procedures were used for the two techniques. Measurements were made on the same amorphous silicon film to provide a direct comparison of the two hydrogen analysis techniques. The hydrogen concentration in the bulk of the film was determined to be about 9 at % H. The SIMS results agree with the resonant nuclear reaction results to within 10%, which demonstrates that quantitative hydrogen depth profiles can be obtained by SIMS analysis …

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19th Annual Conference On Analytical Chemistry Aug 1977

19th Annual Conference On Analytical Chemistry

Rocky Mountain Conference on Magnetic Resonance

Program and abstracts from the 19th annual meeting of the Conference on Analytical Chemistry, co-sponsored by the Rocky Mountain Section of the Society for Applied Spectroscopy and the Rocky Mountain Chromatography Discussion Group. Held in Denver, Colorado, August 1-3, 1977.

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Static Temperature Measurements In Supersonic Flow Using Lasar Raman Spectroscopy, Paul A. Nystrom Jul 1977

Static Temperature Measurements In Supersonic Flow Using Lasar Raman Spectroscopy, Paul A. Nystrom

Mechanical & Aerospace Engineering Theses & Dissertations

Laser Raman spectroscopy is a nonintrusive technique which can generate mean static temperature (MST) data within flow fields. By ratioing two simultaneously gathered portions of the Raman scattered spectrum, absolute intensity measurements were not needed. This method was applied to a supersonic cold air jet, where the NST ranged from 160'K to 300'K. Accurate measurements were not realized due to the presence of flow contaminates, especially water vapor.

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Sio2-Si Film-Substrate Reflection Polarizers For Different Mercury Spectral Lines, A.-R. M. Zaghloul, R. M.A. Azzam Jun 1977

Sio2-Si Film-Substrate Reflection Polarizers For Different Mercury Spectral Lines, A.-R. M. Zaghloul, R. M.A. Azzam

Electrical Engineering Faculty Publications

No abstract provided.

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Can Physics Develop Reasoning?, Robert Fuller, Robert Karplus, Anton E. Lawson Feb 1977

Can Physics Develop Reasoning?, Robert Fuller, Robert Karplus, Anton E. Lawson

Robert G. Fuller Publications

The life of every physicist is punctuated by events that lead him to discover that the way physicists see natural phenomena is different from the way non-physicists see them. Certain patterns of reasoning appear to be more common among physicists than in other groups. These include:
• focusing on the important variables (such as the force that accelerates the apple, rather than the lump it makes on your head);
• propositional logic ("if heat were a liquid it would occupy space and a cannon barrel could only contain a limited amount of heat, but this is contrary to my observations, …

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Compton's 'Crucial Test' - Theoretical Preconceptions And Experimental Interpretation, Roger H. Stuewer Jan 1977

Compton's 'Crucial Test' - Theoretical Preconceptions And Experimental Interpretation, Roger H. Stuewer

Journal of the Minnesota Academy of Science

Arthur Holly Compton, as a result of his own research and confidence in the validity of classical electrodynamics, was convinced in 1921 that homogeneous x-rays and gamma rays could be affected in only two possible ways when passing through matter: either they gave rise to "truly scattered" radiation of the same wavelength as that of the incident rays, or they excited "fluorescent" radiation of a longer wavelength. When Compton was led to carry out experiments using homogeneous x-rays and actually found secondary radiation of longer wavelength, he regarded his result as a crucial test between the "truly scattered" and the …

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Effect Of Compliant Wall Motion On Turbulent Boundary Layers, Dennis M. Bushness, Jerry N. Hefner, Robert L. Ash Jan 1977

Effect Of Compliant Wall Motion On Turbulent Boundary Layers, Dennis M. Bushness, Jerry N. Hefner, Robert L. Ash

Mechanical & Aerospace Engineering Faculty Publications

A critical analysis of available compliant wall data which indicated drag reduction under turbulent boundary layers is presented. Detailed structural dynamic calculations suggest that the surfaces responded in a resonant, rather than a compliant, manner. Alternate explanations are given for drag reductions observed in two classes of experiments: (1) flexible pipe flows and (2) water-backed membranes in air. Analysis indicates that the wall motion for the remaining data is typified by short wavelengths in agreement with the requirements of a possible compliant wall drag reduction mechanism recently suggested by Langley. Copyright © 1977 American Institute of Physics.

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