bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation of Homogeneous n-Type InSb by Thermal-Neutron Irradiation
Authors: Clark W. Gilbert , Isaacson R. A.
Published: January 2005

Thermal neutron irradiation of high-purity (uncompensated, n=4×1013 cm−3) InSb at ambient temperature has been employed to produce n-type material with n=1014−1017 cm−3. The transmutation end products are 98% Sn and 2% Te, both donors. A detailed prescription for producing samples with an accurate control of doping concentration (∼7%), a mobility (μ) at 77°K that is 80%–100% of the highest obtained by other methods, and high homogeneity, is given. Although the reported homogeneity is about 2%, the method is, in principle, capable of much greater homogeneity. A contribution to the nuclear spin-lattice relaxation rate (1/T1) caused by radiation damage is identified. The changes in n, μ, 1/T1, and homogeneity caused by annealing at temperatures up to 450°C are also presented.
Generation of Giant Pulses from a Neodymium Laser with an Organic-Dye Saturable Filter
Authors: Cross Lee A. , Cheng Charles K.
Published: January 2005

There has been much recent interest in the production of high-peak power laser pulses by regeneration switching. Organic dyes have been used as saturable filters for both the ruby (cyanine dyes) and neodymium (a polymethine dye) to produce single high-power spikes.

The cyanine dye, in suitable concentration and path length, can also be used to produce a long train of slightly enhanced (gain about 10) regular Q-switched spikes from the ruby laser, but the neodymium laser can apparently only be operated in the single-pike mode. This paper reports the discovery of saturable filter action in a common dye, rose bengal, a derivative of fluorescein, which permits the production of an extremely regular sequence of enhanced spikes from the neodymium laser. Unlike the previous dyes, the transition corresponding to the saturable absorption occurs between two excited states, not between the ground state and an excited state. The population of the lower excited state is achieved by optical pumping of the dye solution, and, by varying the intensity of the pumping flash lamp, the optical density of the filter may be altered thus changing the spacing between light spikes as well as their height.
Formulation of Dynamic Switching in Distributed Ferromagnetic-Film Systems
Authors: Chang H. , Lin Y. S. , Priver A.
Published: January 2005

The magnetodynamic equation in the Landau-Lifshitz form has been formulated for distributed ferromagnetic-film systems, such as films with laminar magnetization or domain walls. Initial and boundary conditions are examined. The formulation lends itself easily to the numerical solution of both quasistatic- and dynamic-magnetization reversal problems, as illustrated by several examples. A number of applications for the formulation are also indicated.
Mechanism of Charge Transport and Light Emission in ZnSexTe1−x p-n Junctions
Authors: Aven M. , Garwacki W.
Published: January 2005

Electrical transport, photoconductivity, and luminescence measurements have been performed on high-resistivity p- and n-type ZnSexTe1−x crystals. p-n junction diodes prepared from such material, when cooled from 300° to 80°K in the dark, pass very little current and will not emit light. A momentary illumination with radiation of hν>1.9 eV will initiate a steady, efficient light emission, and produce an increase in current by a factor of about 1010. The experimental data obtained will be used to propose a mechanism for the charge transport and light emission in ZnSexTe1−x p-n junctions which involves a self-induced photoconductivity process in both the p- and the n-type bulk of the diodes.
Fixation of Photoelastic Fringe Patterns by Gamma Rays
Authors: Miyazono Shōhachirō
Published: January 2005

It is shown that photoelastic fringe patterns may be preserved at room temperature by γ-ray irradiation of loaded specimens. The samples used in this experiment were prepared from a mixture of epoxy resin and curing reagent (hardener) of the weight ratios of 100 to 12. The effect of irradiation curing was also studied as a function of the irradiation dose and the concentration of the curing reagent. It was seen that the fringe patterns are retained nearly 100% if the total dose is about 2.0×108 R. As an example, a bending test is shown.
Yield-Point Dependence upon Glide-System Orientation
Authors: Gillis Peter P.
Published: January 2005

Various formulations of the Johnston-Gilman concept of yield are investigated using numerical techniques in order to assess the effects of glide-plane rotation on the yield behavior of monocrystals. It is found that such effects are ordinarily small but are of increasing importance as the Schmid factor becomes small. Probably the shape of the yield point is more dependent upon dynamical dislocation effects including strain hardening than on geometrical effects.
Acoustoelectric Current Saturation in CdS as a Fluctuation Process
Authors: Moore A. R.
Published: January 2005

The current through a CdS crystal saturates above a critical electric field at which the electron drift velocity equals the sound velocity, and an internal acoustic flux is generated. At the same time the fluctuations in the current increase enormously. By combining the concept of carrier bunching in the locally generated incoherent acoustic waves with a form of generation-recombination noise process, a two-state, two-parameter phenomenological model has been constructed. The observed noise power and an analysis of the shape of the I-V curve under various conditions are used to derive the parameters of the theory. Dependence on applied voltage, spectral density, temperature, light level, and crystal length for semiconducting and photoconducting crystals support the general expectations of the model. The parameter defining local acoustic wave growth, hence formation of electron bunches, is related to the linear acoustoelectric gain theory. The parameter defining wave decay, hence destruction of electron bunches, is related to the sound transit time. From the noise data and the two-state phenomenological theory, the effective angular frequency of the acoustic waves is found to be about 3×109 sec−1 in a typical semiconducting sample.
Focusing of Microwave Acoustic Beams
Authors: Cohen M. G. , Gordon E. I.
Published: January 2005

A description is given of an experimental study, using Bragg scattering, of the properties of cylindrically-focused longitudinal-wave acoustic beams in fused quartz in the frequency range 200–425 Mc/sec. The results are analyzed and shown to be in good agreement with Fresnel diffraction theory indicating, as expected, that elastic waves at ultrasonic frequencies, because of the extremely short wavelengths involved, propagate as coherent, unguided beams. This allows fabrication of simple focusing elements and makes available efficient light modulation structures as well as techniques for studying the properties of acoustic transducers.
Luminescent Properties of Some Germanate Compounds
Authors: Dugger Cortland O.
Published: January 2005

This qualitative report briefly discusses some properties of some transparent and translucent glasslike germanate compounds and germanate single crystals. These compounds are photoluminescent, thermoluminescent, and phosphorescent. The observable luminescent effects, although only partially understood, are reproducible.
A Thin-Film CdS-Quartz Composite Resonator
Authors: Sliker T. R. , Roberts D. A.
Published: January 2005

A new type of miniature resonator for the 100–1000-MHz range has been developed which consists of a piezoelectric CdS transducer evaporated onto a single-crystal quartz wafer. Energy trapping principles have been applied to localize the acoustic energy in the quartz wafer to the volume under and immediately surrounding the electrically driven CdS film. Resistances at resonance of 50 Ω and electrical Q's of 5000 typically have been realized with 279-MHz devices. Both shear and longitudinal mode resonators have been fabricated, but shear mode operation has the important advantage that devices with a zero frequency-temperature coefficient are possible.
Elastic Moduli of GaAs at Moderate Pressures and the Evaluation of Compression to 250 kbar
Authors: McSkimin H. J. , Jayaraman A. , Andreatch P.
Published: January 2005

Ultrasonic wave velocities in GaAs have been measured at 25°C as a function of hydrostatic pressure. The adiabatic ``zero-electric-field'' stiffness moduli calculated from these velocities are as follows: c11=1.1877± 0.0006, c12=0.5372±0.0009, c44=0.5944±0.0003. All moduli are in units of 1012 dyn/cm2 and are based on a density of 5.3169 g/cm3 taken as exact with respect to estimates of errors. Hydrostatic pressure derivatives for c11, c12, and c44, are, respectively, 4.63±0.03, 4.42±0.05, and 1.10±0.02. From the isothermal bulk modulus (BT) of 746.6 kbar and its pressure derivative (∂BT/∂P) of 4.67 calculated using the above data, the static compression of GaAs has been computed to a pressure of 250 kbar.
Magnetoelastic Resonances in Ferrite Memory Cores
Authors: Boyd E. L.
Published: January 2005

The acoustical resonant modes of a ferrite memory core have been identified and related to the flux configuration. A simple calculation is given which indicates the relationship of the amplitude of the resonance to the single-crystal parameters. The line width has been measured as a function of temperature and related to the relaxation of the permeability.
Nature of the Electrical Conduction Transients Observed in CeO2 and Ca-Doped CeO2
Authors: Blumenthal R. N. , Pinz B. A.
Published: January 2005

The electrical conduction transients of CeO2 and ca-doped CeO2 were investigated by employing a constant-current dc power source and a six-probe high-resistance input-isolated recording system.

In contrast to the observations made by Kevane et al. neither voltage-time transients nor non-Ohmic behavior were observed when high-purity CeO2 (99.9% min.) was investigated in the temperature range 300° to 1000°C.

Transients were observed for the high-purity CeO2 specimen when loading due to the instrumentation occurred or when high current densities due to a small contact area were used at the contacts. A model based on electrolysis was used to explain these results.

Voltage transients at constant current were observed on a CeO2 specimen doped with 1 wt% CaO in argon but not in oxygen. These transients increased with increasing temperature in contrast to the observations made by Kevane.

At 960°C in argon potential distribution curves at several different times showed that the electrical conductivity increases with time and was larger at the negative end of the sample than at the positive end where the conductivity decreases with time initially. After longer periods of time the conductivity increased over the entire specimen. In addition the specimen exhibited a discolored region; the intensity of the discoloration decreased with increasing distance from the cathode. After reoxidation at 1000°C in air the discolored region disappeared and the weight of the specimen increased. These results were explained in terms of a model that assumed blocking of the oxygen vacancies and oxygen ions at the cathode and anode, respectively. The electrons were then distributed so that electroneutrality was preserved. Thus the electrical conductivity was dependent upon the distribution of the oxygen vacancies and the oxygen ions. After longer times the voltage transients were controlled by electrolysis.
Domain Formation in a Ferromagnetic Plate
Authors: Muller M. W.
Published: January 2005

The nonlinear micromagnetic equations are used to obtain an approximate analytical solution for the distribution of the magnetization vector in the central plane of a ferromagnetic plate with uniaxial magnetocrystalline anisotropy. It is shown that the micromagnetic nucleation mode derived from the linearized equations develops into a strip domain pattern with well-defined Bloch walls in a rather narrow range of applied magnetic field near the saturation value. The stability of the domain pattern is discussed qualitatively.
Defects in the Compound Bi2Te3 caused by Irradiation with Protons
Authors: Chaudhari P. , Bever Michael B.
Published: January 2005

Single-crystal foils of the compound Bi2Te3 were irradiated with 7.5-MeV protons at two levels of flux to the same integrated dose of 5.5×1018 protons/cm2. The specimens were examined by transmission electron microscopy. After irradiation with a flux of 1.8×1013 protons/cm2·sec, clusters of point defects ranging in size from approximately 50 to 250 Å were observed. These clusters annealed out during examination in the electron microscope. After irradiation with a flux of 3.0×1013 protons/cm2·sec, clusters of interstitial atoms and clusters of vacancies could be distinguished. Hexagonal areas were observed after irradiation with the higher flux. Irradiation also promoted the rearrangement of dislocations. Segments of dislocations intersected the surface of the specimens, and some dislocations acquired a jagged appearance.
Microwave Faraday Rotation in Nickel-Powder Artificial Dielectric—A Suggested Explanation
Authors: Datta A. N. , Engineer M. H. , Nag B. R.
Published: January 2005

It is shown that the anisotropic permeability of the magnetic particles constituting an artificial dielectric provides an explanation for the rotation of the plane of polarization and the variation of the attenuation of a plane-polarized electromagnetic signal propagating through the dielectric in the presence of a longitudinal magnetic field. The attenuation curve is found to be readily explainable from the nature of variation of the power transmitted into the particles. A more detailed agreement between experimentally observed rotation, attenuation, and computed values is shown to follow if Lewin's formulas for the permeability and permittivity of an artificial dielectric is assumed to be valid also for circularly polarized signals. The effect of the size and permeability of the metal particles on the figure of merit of rotation is also discussed.
Longitudinal Magnetoresistance and Hall Mobility of n-Type Germanium at High Electric Fields
Authors: Nag B. R. , Paria H. , Guha S.
Published: January 2005

The longitudinal magnetoresistance and Hall mobility of 5-Ω·cm n-type germanium have been measured for electric fields applied in the (111) direction up to 4 kV/cm. It has been found that (i) longitudinal magnetoresistance at a particular electric field decreases with an increase in the magnetic field, (ii) for small magnetic fields the longitudinal magnetoresistance decreases with an increase in the electric field, and (iii) the Hall mobility and the ratio of Hall mobility to the conductivity mobility decrease with an increase in the electric field.

The experimental value for fields above 1 kV/cm are found to agree with the theoretical values calculated with the assumptions that (i) the scattering is due to the acoustic, optical, and intervalley phonons, (ii) the average energy of the electrons is much larger than that of the optical phonons, (iii) the intervalley phonons affect only the carrier repopulation in the different valleys, and (iv) the value of the optical-phonon deformation potential constant is 0.8×109 eV/cm.
Cathodoluminescence of MgS:Ce,Ni
Authors: Gilliland J. W.
Published: January 2005

The phosphor MgS:Ce,Ni is an efficient cathodoluminophor with green to yellow emission and very short decay time. The addition of nickel produces lower efficiency and correspondingly faster decay, the exact relation depending on the cerium concentration. The optimum composition for high efficiency (5–10 lm/W) and fast decay (0.25–0.35 μsec) was found to be MgS:Ce (0.001), Ni (0.0002). The primary green luminescence was shown to result from cerium doping rather than from some other impurity.
Effect of Impurities on the Annealing Behavior of Irradiated Silicon
Authors: Hirata Mitsuji , Hirata Masako , Saito Haruo , Crawford James H.
Published: January 2005

The effect of impurities on the annealing behavior of irradiated silicon was studied through an investigation of isothermal annealing of minority carrier lifetime in silicon crystals containing phosphorus, arsenic, antimony, or bismuth in the temperature range 100°–180°C. The activation energy for the annealing of vacancy-impurity complex increased with increasing atom size of the dopant. The values are 0.93, 1.27, 1.84, and 2.22 eV. The frequency factor was also found to be dependent on impurity as well as concentration of the complex. The variation of these parameters is discussed in terms of the lattice strain associated with impurity atoms which have a larger covalent radius than silicon.
Nature of Electrical Contact between Tarnished Surfaces
Authors: Tripp J. H. , Snowball R. F. , Williamson J. B. P.
Published: January 2005

The variation of contact resistance with temperature has been measured on clean and tarnished silver contacts between 77° and 420°K. It is shown that the temperature coefficient of resistance provides a direct method of distinguishing film conduction from metallic conduction in contacts, and conversely that a single measurement at room temperature cannot reliably yield this information. Clean contacts have the positive temperature coefficient of resistance of the conductor metal. A film-covered contact on the other hand exhibits either of two distinct types of temperature dependence: one with a large negative temperature coefficient, and one that is metallic. It is suggested that these occur according to whether mechanical contact is made on the film or through a small fissure in it. If the contact is mechanically disturbed, the nature of the conduction fluctuates randomly between these two modes.

Further, the temperature coefficient of resistance provides a means for distinguishing between semiconducting and tunneling contacts. The experimental observations on silver sulfide tarnish film suggest that electron tunneling is dominant at cryogenic temperatures, but that at normal temperatures the film is an n-type semiconductor.
Anisotropy of Nonelastic Flow in Bone
Authors: Bonfield W. , Li C. H.
Published: January 2005

The microdeformation characteristics of 0.010-in.-diam compact bone filaments have been measured under torsional loading conditions. The effects of prestrain, recovery, cyclic loading, and specimen orientation on the nature and extent of the nonelastic flow were determined. Correlations are considered between the mechanical behavior and the composite structure of compact bone.
Phase-Shift-Corrected Thickness Determination of Silicon Dioxide on Silicon by Ultraviolet Interference
Authors: Wesson R. A. , Phillips R. P. , Pliskin W. A.
Published: January 2005

A spectrophotometer operating in the ultraviolet region can be used to obtain accurate and precise silicon dioxide thickness determinations on silicon. Excellent accuracy and precision is obtained by considering: (1) the refractive-index dispersion of the silicon dioxide; and (2) the theoretically calculated phase shifts at the silicon dioxide-silicon interface based on known optical constants of silicon. Experiments comparing spectrophotometric oxide thickness determinations against VAMFO (variable-angle monochromatic fringe observation) thickness determinations indicate an accuracy of ±25 Å and a precision of ±15 Å.
Two-Stream Instability in Semiconductor Plasmas
Authors: Robinson B. B. , Swartz G. A.
Published: January 2005

Pines and Schrieffer demonstrated that the two-stream instability could occur in a high-mobility semiconductor such as InSb if the conditions ωp+τ+>10 and T−»T+ are satisfied, where ωp+ is the hole-plasma frequency, τ+ is the hole-collision time and T− and T+ are the electron and hole temperatures, respectively. Either condition is difficult to obtain in bulk InSb. The possibility of observing such an instability in a structure consisting of adjacent p and n InSb is considered. The collision condition is reconsidered using a collision term which conserves particles and assuming the somewhat higher electron-drift velocities (≃electron-thermal velocity) which are now believed possible. It is concluded that the condition can be relaxed by about an order of magnitude (ωp+τ+>1). The layered structure could provide the condition T+«T− if it were in contact with liquid helium while a current, passed only in the n region, produced both relative streaming and elevated electron temperatures. A comparative stability analysis in the zero-temperature fluid limit indicates that the surface space-charge waves of the layered structure can grow at rates only slightly less than those of the bulk space-charge waves of the corresponding penetrating stream system.
Fluctuations in Luminescent Junctions
Authors: Brophy James J.
Published: January 2005

Optical-emission fluctuations from three types of GaAs and Ga(AsP) p-n junction luminescent diodes have been examined. Characteristic time constants of 12×10−3 and 0.45×10−3 sec are observed in both the optical noise spectra and forward-current noise spectra of a GaAs diode in which carrier recombinations occur in the junction space-charge region. More heavily doped junctions (∼1019 cm−3), in which tunnel currents predominate, exhibit 1/f noise. In either case, correlation exists between optical-emission noise and forward-current noise, suggesting that carrier transitions responsible for both effects are the same. Only simple photon noise is observed from a Ga(AsP) diode in which junction diffusion currents are significant, although the forward noise spectrum is also 1/f noise.
Effect of MgO on the Crystal-Growth Defects and Optical Absorption of Flux-Grown In2O3
Authors: Chase A. B. , Tippins H. H.
Published: January 2005

Crystals of In2O3 grown from a pure flux have inclusions and striations and, because of oxygen deficiency, are nonstoichiometric and almost black. The addition of MgO to the melt produces crystals that have no inclusions or striations, and that have optical properties characteristic of stoichiometric In2O3. Therefore, Mg acts as an efficient compensator of the oxygen deficiency. This paper describes the effect of MgO on the visible optical absorption spectrum and on the crystal defects. One possible model of the role of Mg in compensating In2O3 is discussed briefly.
Microscopic Evidence of Plastic Deformation on Cleaved Germanium Surfaces
Authors: Noble W. P. , Henisch H. K.
Published: January 2005

A study of cleaved germanium surfaces by transmission electron microscopy and gold transfer replicas provides direct and indirect evidence of plastic deformation introduced by the cleavage process at room temperature. The results are interpreted as showing that dislocations move by glide on {111}-type planes parallel to the surface and at 70°32′ to the surface. Experiments are also reported using copper plating as a technique for decorating surface damage.
Sink-Terminated Concentration Quenching of Trivalent Gadolinium and Ytterbium Fluorescence
Authors: Pearson A. David , Northover W. R.
Published: January 2005

The lifetimes of Gd3+ 6P7/2 and Yb3+ 2F5/2 fluorescence in a glass host have been studied at room temperature as a function of concentration, and in the case of Gd3+ as a function of added Eu3+ concentration. The results show that the ions ``concentration quench'' by a mechanism involving the migration of excitational energy from ion to ion until a sink in the structure is reached. This result is significant to the preparation of laser materials.
X-Ray Study of Proton-Induced Disorder in Cu3Au
Authors: Kosaki M. , Smith Harold P. , Khan J. M. , Potter D. L. , Worley R. D.
Published: January 2005

Measurement of fundamental and superlattice x-ray diffraction lines as a function of integrated proton-bombardment current has been used to determine induced disorder in the surface layers of fully ordered polycrystalline targets of Cu3Au. It is shown that a proton range for induced disorder and the number of disordered atoms created per proton can be inferred from the data.
Elastic Moduli of Single-Crystal Spinel at 25°C and to 2 kbar
Authors: Schreiber Edward
Published: January 2005

The elastic properties of a synthetic single-crystal spinel with a composition of MgO·2.6Al2O3 have been determined at 25°C and up to 2 kbar by measuring propagational velocities of ultrasonic waves using the method of pulse superposition. The isotropic moduli and Poisson's ratio were computed from the single-crystal values using the Voigt-Reuss-Hill approximation.

Values of the adiabatic elastic moduli at 1 bar and 2 kbar and at 25°C are c11c12c441 bar2985.71537.21575.8(kbar)2 kbar2995.51545.01577.5(kbar).

The adiabatic bulk modulus was computed to be 2019.9 kbar, and the pressure derivative of the adiabatic bulk modulus was found to be 4.18.
Dynamic Mechanical Properties of the Transcrystalline Regions in Two Polyolefins
Authors: Kwei T. K. , Schonhorn H. , Frisch H. L.
Published: January 2005

The dynamic Young's moduli E of molded films of a polyethylene and a polypropylene were found to decrease with increasing thickness t. An upper limit of E appears to exist when the film thickness is reduced to less than 1 mil. For thicker films, E is inversely proportional to t. Finally, the modulus approaches a lower asymptotic value when t is in excess of 20 mil. The results can be represented quantitatively by a model in which the surface transcrystalline region and the bulk phase of the polymer respond in a parallel combination to the applied stress. The modulus of the transcrystalline region in each polymer is higher than that of the bulk phase. The thickness of a surface region is about 12 μ in polypropylene and 15 μ in polyethylene. The effects of thermal history and the nature of the molded surface were examined briefly.
Comment on the Initial-Rise Method for Determining Trap Depths
Authors: Bräunlich P.
Published: January 2005

For the determination of the trap depth from thermoluminescence and thermally stimuated current-glow curves commonly the initial-rise method by Garlick and Gibson is used. This method provides accurate results only if the condition Rh(T0)[2/z−1] ≤f(T0) is fulfilled. R is the retrapping factor, z the filling ratio of the traps at the temperature T0, f the concentration of unoccupied recombination centers, and h the density of trapped electrons.
Wing-Slope Techniques for the Analysis of Langmuir-Probe Characteristics in a Low-Density Plasma
Authors: Bettinger Richard T.
Published: January 2005

The volt-ampere characteristics of Langmuir probes utilized in ionospheric investigations and employing ideal geometries (spherical or cylindrical) contain a considerable amount of information, much of which is not utilized in the usual analysis programs. The slope of the V-i curve for large accelerating potentials contain a substantial amount of information on mass density and temperature. We have developed equations for the current and its slope in this region for both of the above geometries and have applied them to a few typical situations. We conclude that the usefulness of Langmuir-probe techniques may be appreciably improved by performing a ``total analysis'' on the available information. In some cases, measuring the slope directly will supply the same information with a substantial saving in experimental complexity.
The Voigt-Reuss-Hill Approximation and Elastic Moduli of Polycrystalline MgO, CaF2, β-ZnS, ZnSe, and CdTe
Authors: Chung D. H. , Buessem W. R.
Published: January 2005

The Voigt-Reuss-Hill (VRH) approximation, a useful scheme by which anisotropic single-crystal elastic constants can be converted into isotropic polycrystalline elastic moduli, is shown to apply for moderately anisotropic cubic crystals like MgO, CaF2, β-ZnS, ZnSe, and CdTe. Experimental values of polycrystalline isotropic elastic moduli for these materials are presented here, and the validity of the VRH approximation is established. The VRH approximation is then discussed for these materials with respect to their elastic anisotropy of crystals. To provide further support to this work, a numerical confirmation on the VRH moduli is made with the use of a high-speed computer by calculating the mean velocity of sound in crystals and comparing this result with the corresponding quantity calculated from the actual polycrystalline elastic moduli. The general agreement is observed.
Behavior of Saturable-Absorber Giant-Pulse Lasers in the Limit of Large Absorber Cross Section
Authors: Erickson L. E. , Szabo A.
Published: January 2005

Using a rate-equation model, it is shown that the behavior of the saturable-absorber giant-pulse (SAGP) laser can be adequately described in terms of two parameters for values of the ratio of absorber to laser absorption cross section σ>200: nai′ the normalized initial inversion and στs, where τs is the normalized absorber relaxation time. In the general case, specification of nai′, σ, and τs is required. Theoretical curves of the giant-pulse output power, energy, and rise- and falltimes are presented. The results are applicable in particular to SAGP lasers employing organic-dye absorbers.
Self-Diffusion of Tritium in Natural and Synthetic Ice Monocrystals
Authors: Ramseier René O.
Published: January 2005

The self-diffusion of tritium in artificially and naturally grown ice monocrystals, parallel and perpendicular to the optical axis, was studied between −2.5° and −35.9°C. The plane-source solution to Fick's second law was used in treating the data. An anisotropy of ≈ 12% was observed. The activation energy was found to be 0.62 eV for all cases and D0 ≈ 10 cm2/sec. Based on the experimental data, it is concluded that the diffusion takes place by a vacancy mechanism, and that entire H2O molecules are diffusing, i.e., molecular diffusion occurs. Theoretical calculations using the atomic-diffusion theory and Zener's theory for D0 are in excellent agreement with the experimentally determined diffusion coefficient.
Radiation from Current Sources in an Isotropic Plasma
Authors: Connolly Denis J. , Tanenbaum B. Samuel
Published: January 2005

Using a three-fluid model, wave equations are developed for the disturbances due to current sources in a partly ionized gas. The formal solutions to the wave equations are obtained for an elementary current source. The power radiated from the source is given in terms of these solutions and, for the special case in which the electrons are much hotter than the other two constituents, the radiated power is determined in detail.
Thick Cylindrical Coil Systems for Strong Magnetic Fields with Field or Gradient Homogeneities of the 6th to 20th Order
Authors: Garrett Milan Wayne
Published: January 2005

For strong homogeneous fields the ideal loop and solenoid elements of a prototype system may be expanded into thick cylindrical coils whose current density is (a) uniform or (b) inversely proportional to the cylindrical radius. Error coefficients of the zonal harmonic series for field or gradient that are cancelled in any given prototype continue to vanish as the elements are expanded, even to fusion, if at each stage the coil boundaries are adjusted by an iterative method. This involves the use of (a) the harmonic source functions Un* or (b) the Legendre functions Pn; either set is best computed by a recursion formula. An alternative method based on Lyle's principle requires no iterations and only trivial calculations. Though it also is valid for systems of any order, it can only expand a set of loops into coils with square cross sections of limited area. Also, the true null coefficients are replaced by small residues proportional to 4th and higher powers of the section dimensions when the second method is used.

The number of tabulated prototype systems of the 6th and 8th orders is increased to more than 200. Since multiply infinite sets of prototypes can be computed for every order higher than the 8th, univariate tables would be inadequate and only a few illustrative examples of such systems are given. Some 150 thick-walled systems of the 6th or 8th order are listed in several tables, but such a selection can only suggest the wide range of possibilities. These systems have more degrees of freedom than do the corresponding prototypes, and even the 6th order is multivariant. At the 8th order and beyond, the growing redundancy of variables permits the design of systems with a common current density in all coils and with all section dimensions proportional to a set of small integers. Systems of order 4n have paired coils with gaps for lateral access, an advantage that is lacking in the 6th-order designs.

Efficient computer programs have been written to design systems of all the types so far enumerated, including multiple sets of both prototypes and fully adjusted systems of thick coils for orders from 8 to 20 in steps of 4. Since adequate tabulation of results is ruled out by their diversity and sheer bulk, in view of the wide range of potential applications the programs themselves must be considered the basic research tool. They will be described in detail elsewhere.

As a measure of field inhomogeneity, including contributions from all orders and from both axial and radial field components, the concept of total vector error is developed. The tables include error limits for all systems, and some 40 systems or their error contours are shown in the figures.
Effect of Stacking Faults and Twins on the Coercive Force of Thin Magnetic Films
Authors: Walker G. A. , Larson H. W.
Published: January 2005

The effects of fairly high densities of extrinsic stacking faults (α approximately as large as 0.3) and twins (β approximately as large as 0.15) on the coercive force, Hc, of thin (less than 700 Å) ferromagnetic Fe-Co-Ni films are studied.

Once the effects of strain and small crystallite size on Hc are eliminated, it can be shown that stacking faults and twins increase the Hc, stacking faults having a larger effect than the twins. The introduction of the faults was achieved by sputtering onto ``unclean'' substrates, which gave an initial small-crystallite-size layer of about 100 Å, where the crystallite size gradually increased to that found on ``clean'' substrates. At the intersection of the two layers, there was a layer of faults extending about 200 Å into the larger-crystallite-size film. The x-ray technique used to evaluate thickness variation of faults is described.
Stability of an Electrified Liquid Jet
Authors: Schneider J. M. , Lindblad N. R. , Hendricks C. D. , Crowley J. M.
Published: January 2005

A capillary wave of the appropriate wavelength will cause a jet to break up into a stream of uniform-sized droplets. In this paper, a theoretical expression for droplet size, radius, and spacing in terms of the jet parameters and applied frequency is derived and verified experimentally. For a given jet radius and velocity, the droplet size can be varied from its minimum value, rmin, to approximately 1.6rmin by varying the driving frequency. Also, a theoretical expression for the charge on droplets resulting from the disintegration of a charged jet is shown to agree with the measured value of droplet charge.
Third-Order Elastic Moduli of Gallium Arsenide
Authors: McSkimin H. J. , Andreatch P.
Published: January 2005

The six third-order moduli of GaAs have been determined by measurement of ultrasonic wave velocities (time delays) as a function of applied stress. The adiabatic values (in units of 1012 dyn/cm2) at 25°C and for zero electric field are very similar to those previously obtained for Si and Ge, as can be seen from the following table: ModulusGaAsGeSiC111−6.22±0.06−7.10−8.25C112−3.87±0.03−3.89−4.51C123−0.57±0.06−0.18−0.64C144+0.02±0.09−0.23+0.12C166−2.69±0.06−2.92−3.10C456−0.39±0.09−0.53−0.64.
Stress and Displacement Fields of an Edge Dislocation that Climbs with a Uniform Velocity
Authors: Weertman J.
Published: January 2005

The stress and displacement fields of an edge dislocation that climbs with a uniform velocity are derived. This solution has application for the determination of the stress and displacement field arising from the anomalous edge component of a moving partial dislocation. The climb motion of the anomalous edge component does not involve diffusion of point defects and is not restricted to slow velocities. The self-energy of a climbing edge dislocation also is determined. It is found that the self-energy diverges as (1−V2/c2)−1/2, where V is the dislocation velocity and c is the transverse sound velocity when the dislocation velocity approaches the slow sound velocity. This divergence is not as strong as that of the gliding edge dislocation [which is (1−V2/c2)−3/2].
Effects of Film Geometry on Superconductive Tunneling
Authors: Gillespie C. J. , Rachinger W. A.
Published: January 2005

The effect of exceeding the critical current in one film of a superconducting tunnel junction is examined. The position of the normal superconducting boundary is calculated for a simplified model, and the form of the current-voltage relation is discussed. Nonuniformity of the film is shown to cause anomalous characteristics observed in Pb-PbO-Al junctions.
Slip-Induced Directional Order in Fe-Ni Alloys. II. Experimental Observations
Authors: Chin G. Y. , Nesbitt E. A. , Wernick J. H. , Vanskike L. L.
Published: January 2005

The results of an extensive investigation into the nature of slip-induced directional order in Fe-Ni alloys near the 75% Ni composition are reported in this paper. Single crystal rods of 4–79 moly-Permalloy were swaged in the [111] and [001] orientations, as were crystals of the following orientations subjected to plane strain compression: (001) [100], (001) [110], (110) [001], (110) [1̄12], (110) [1̄10], (111) [1̄12], (112) [1̄10] and (112) [1̄1̄1]. Magnetic torque measurements show that all crystals developed a uniaxial anisotropy upon deformation, with the easy magnetic direction in good agreement with our previous theoretical deductions. In the [001] swaged crystal, deviation of the observed easy axis from the calculated value was rationalized in terms of unequal participation of the expected slip systems.

In all cases of plane strain compression, the induced anisotropy constant rose to a maximum value, and then decreased, as the thickness reduction was increased. In one experiment, crystals of a 2%Mo-76% Ni-22%Fe alloy received a long-range-ordering treatment at 475°C for 190 h prior to plane strain compression in the (110) [1̄12] orientation. The anisotropy energy reached a maximum value of 460 000 erg/cm3, the highest value of slip-induced anisotropy thus far reported in Fe-Ni alloys. As for the anisotropy decrease at large reductions, reorientation of slip-induced atom pairs as a result of lattice rotation, is undoubtedly a factor. However, this explanation is not valid for the (110) [1̄12] orientation, which remained stable even after 98% reduction. A more widely applicable mechanism is advanced, whereby the decrease in anisotropy is attributed to randomization of the atom pairs through slip across antiphase ordered domain boundaries, both those grown-in and those created by intersecting slip.

Additional observations have been made of the crystallographic texture and magnetic squareness in cold-formed polycrystalline Permalloy tapes, which are currently used as magnetic memory elements in storage devices. The results are satisfactorily explained in terms of slip-induced directional-order theory. Implications of seeded single crystals to these results are discussed.
Thermal Emission Microscope Studies of Cesium Surface Ionization on Porous Refractory Metals
Authors: Jamba D. M. , Husmann O. K.
Published: January 2005

Quantitative thermal emission microscope studies of cesium surface ionization on porous tungsten emitters show under clean surface conditions a surface migration length in the 2-μ range. The migration length from the pore exit is under this condition fairly independent of the flow rate per pore and the emitter temperature. It is therefore concluded that 107 pores/cm2 (traverse counting technique) yield maximum ionization efficiency on porous tungsten.

Clean surface conditions were checked by Richardson work function measurements with the built-in Faraday cage. Also, the ion-current transition pattern in the threshold region was used for judgement of the surface condition. In case of a contaminated surface, a smooth transition from high to low ion current with decreasing temperature was observed in contrast to the steep ion-current change-over in the threshold region under clean surface conditions. Also the surface migration length increased on the contaminated surface.

Molybdenum, sputtered onto the porous tungsten substrate, showed a uniform work function over the entire emitter area with φ=4.20 eV.
The Bi I-II Transition Pressure Measured with a Dead-Weight Piston Gauge
Authors: Heydemann Peter L. M.
Published: January 2005

A dead-weight piston gauge was used to determine the bismuth I-II transition pressure and the volume change at the transition. The transition pressure at 25°C for one sample, believed to contain less than 0.001% impurities, was found to be 25 306 bar, with an estimated uncertainty of 60 bar. With another sample, of substantially less purity and of larger grain size, a transition pressure of 25 500±60 bar was measured. The average relative volume change was 0.035.
Electrical Currents Produced during the Solidification of Water (Costa Ribeiro Effect)
Authors: Pinatti D. , Mascarenhas S.
Published: January 2005

A new type of cell for investigation of the Costa Ribeiro effect in water is described. The rate of change of water to ice can be controlled and measured, while the associated current is measured. The current is found to be proportional to the rate of change of water to ice and between 1 and 10 μC of charge are liberated for each gram of water frozen. The possible importance of the effect for the explanation of atmospheric electricity is discussed.
Correlated Structure in Evaporated Cermet Films
Authors: Scott R. E.
Published: January 2005

Flash-evaporated cermet films (Cr-SiO) with 77 wt % Cr were examined by x-ray diffraction. Bragg peaks corresponding to extremely small particles of Cr were observed. For specimens deposited onto room-temperature Pyrex substrates, a particle size of 20 Å was calculated from the breadths of the peaks. For specimens deposited at 400°C, the Bragg peaks took on an unusual form, consisting of a central peak flanked by strong subsidiary peaks, or sidebands. These sidebands are interpreted as evidence for a strong crystal-lographic correlation, in both separation and orientation, between chromium particles. A model consisting of short chains of touching Cr particles, with correlation only between nearest-neighboring particles, and a particle size of 15 to 20 Å, is consistent with the observations on the 400°C specimens.
Control of Ion-Acoustic Wave Instabilities in a Gaseous Discharge
Authors: Coleman James T.
Published: January 2005

The marginal-stability boundary for spontaneous generation of ion-acoustic waves in a nonequilibrium plasma is investigated experimentally. The transition from inverse Landau damping to normal Landau damping of the acoustic wave modes is demonstrated by observing the change in forward-scattering cross section of microwave electromagnetic energy. The measured scattering cross section is compared with that predicted by Ichimaru, using a simple relaxation-time collision term in the Boltzmann equation. In addition, the collision term of Bhatnagar et al. is used to construct a new marginal-stability boundary. The latter expression seems to give a better comparison with the observed microwave scattering and demonstrates the superiority of the more realistic collision-term model.
Bolometric Detection of Coherent 9-GHz Longitudinal Phonons in X-Cut Quartz
Authors: Andrews John M. , Strandberg M. W. P.
Published: January 2005

Coherent longitudinal phonons at 9.0 GHz in X-cut quartz rods have been detected by means of high-speed superconducting bolometers. This type of detector is responsive to ultrasonic intensity and is insensitive to the ultrasonic phase distribution over the endface of the quartz rod, which often disguises the true nature of the echo-decay envelope when piezoelectric detection of microwave phonons is employed. These bolometers are also capable of detecting the incoherent phonons produced in the dissipation and thermalizing of the coherent microwave phonons.
Effects of Transverse and Longitudinal Nonuniformities in Conductivity on Ultrasonic Propagation in CdS
Authors: Davis E. A. , Drews R. E.
Published: January 2005

Ultrasonic propagation in piezoelectric crystals as a function of conductivity and electric field has been theoretically described by White. Deviations from the theory are frequently encountered in materials such as CdS, and explanations in terms of trapping, transducer misalignment, dielectric relaxation effects, and nonuniformities in conductivity have been invoked. In this paper the effects of conductivity variations along (longitudinal) and perpendicular (transverse) to the direction of sound propagation on ultrasonic attenuation and amplification characteristics are considered. It is assumed that White's theory is valid locally. The effects of conductivity inhomogeneities are shown to be significant even for relatively small departures from uniformity. Longitudinal variations are especially important, because the electric field required to produce zero attenuation, which is frequently used for determining drift mobilities, shows a considerable variation with measured sample conductivity. A discussion in terms of experimental observations is presented.
Aging and Skew in Permalloy-Base Magnetic Films
Authors: Slonczewski J. C. , Ainslie N. G. , Beam W. R.
Published: January 2005

A summary of the results of experiments to determine the magnetic aging characteristics of ``Chainstore'' memory elements as a function of time, temperature, and electrical exercise is presented. A phenomenological theory of anisotropy kinetics is constructed which provides an account of aging in magnetic films in agreement with the ``Chainstore'' experiments. The theory, which is capable of simple geometric representation, describes the kinetics by which the uniaxial anisotropy constant and skew angle change when a device is subjected to magnetic annealing at an elevated temperature. Conclusions are also drawn in regard to the phenomena of angle and amplitude dispersion.
Parametric Coupling between Ion and Electron Waves
Authors: Sjölund A. , Stenflo L.
Published: January 2005

Parametric coupling between ion and electron waves is studied by means of coupled-mode theory. The coupling coefficients are determined. Two examples of parametric coupling are considered. One results in amplifying waves and the other in an absolute instability. The growth rate is calculated.
Propagation of a Longitudinal Strain Pulse along a Single-Crystal Bar
Authors: Hensel R. D. , Curtis C. W.
Published: January 2005

An experimental study has been carried out to determine how the behavior of an elastic pulse produced by step-function pressure loading of a single-crystal lead bar, depends on the orientation of the crystal relative to the axis of the bar. It was observed that the strain-time records had the same general characteristics as in the case of an isotropic bar. The effect of varying the crystal orientation was to change the velocity of the pulse, the amount by which it disperses, and its amplitude. For lead, the velocity and amount of dispersion can be changed by a factor of approximately two and the amplitude by a factor of five. Reasonable predictions of this behavior result from an approximate equation of motion developed on the same assumptions as used by Love for an isotropic bar.