bluuebunny/crossref_metadata_2025_split huggingface dataset:
Time-Dependent Electron Flow
Authors: Pease M. C. 
Published: April 2005

The conditions of self-consistency for electron flow through arbitrary static or time-varying electric and magnetic fields are established assuming (a) nonrelativistic flow, (b) single streaming–i.e., the velocity has a single value and direction at every point, and (c) the electrons originate on a cathode not threaded by magnetic lines of force. In the case where the magnetic field is constant and uniform, a single-vector differential equation can be written which determines all possible solutions.
From this equation certain time-variant solutions are developed. These are fully self-consistent–that is, large signal–solutions which exhibit some of the nonlinear behavior that would be expected of such solutions.
Probably the most interesting of these solutions–since it offers an explanation of an observed phenomenon that does fit previous theory–is a radial oscillation of the cloud in a filamentary cathode smooth bore magnetron at ω/2.
The possible application of the other solutions to anomalous behavior in various magnetron type devices is also discussed.
Longitudinal Wave Propagation in Stretched Polymers
Authors: Mason Peter 
Published: April 2005

The wave equation is derived for the propagation of longitudinal waves along a stretched filament of a highly elastic material. It is found that the tension in the filament reduces the effective modulus by twice the product of Poisson's ratio and the tensile traction, leaving the internal viscosity term unchanged. This result is illustrated by measurements of continuous 1 kcps wave propagation in natural rubber at 50°C, where the damping is small (tan δ&lt;0.1). An alternative derivation is given for the purely elastic case of zero damping without restriction upon the amplitude.
The ``equilibrium'' or ``static'' Young's modulus is obtained for extensions up to about 600% from the slope of the equilibrium stress-strain curve and used to predict the corresponding wave velocities from the wave equation for zero damping. The predicted velocities are slightly higher—by up to about 10%—than the measured velocities. It is shown that the deviations could arise from differences in rate of strain between the wave-propagation and the stress-strain measurements. At the higher extensions the rubber is very hysteretic for large deformations, and the Young's modulus governing the small-amplitude wave propagation is shown to relate substantially to the loading branch of the stress-strain curve.
Effect of Temperature and Reactor Irradiation on the Strength of Biaxially Oriented Polyethylene Terephthalate
Authors: Haynes A. , Hsiao C. C. 
Published: April 2005

Samples of biaxially oriented polyethylene terephthalate irradiated in a nuclear reactor have been investigated at five temperature levels ranging from − 150°F to 350°F. In general, from tensile studies, the ultimate tensile strength was found to decrease markedly to a relatively low magnitude upon receiving a reactor irradiation dose having a thermal neutron bombardment component of 1018 nvt and over. The modulus of elasticity for both the irradiated and nonirradiated samples was found to increase with the decrease of the temperature.
The fracture surfaces of the biaxially oriented polyethylene terephthalate samples obtained at − 15°F are also recorded for reference.
Wave Functions and Energy Eigenvalues for the Polytetrafluoroethylene Chain
Authors: Pao Yoh-Han , Bjorklund R. F. 
Published: April 2005

The paper reports on a quantum mechanical investigation of an isolated polytetrafluoroethylene molecule. The purpose of this investigation is twofold: to find the energy gap between filled and empty electronic bands and to determine the energy required to change the conformation of the molecule. For reasons of simplicity, the carbon atoms are assumed to have the planar zigzag conformation in the ground state of the molecule. Molecular wave functions are constructed from Bloch sums taken along the four rows of fluorine atoms. The basis functions used are Gaussian approximations to 2p and 3s atomic orbitals. The suitability of this choice is tested in a preliminary calculation of the dissociation energy of the hydrogen fluoride molecule.
In polytetrafluoroethylene, the molecular orbitals form bands. The energy gap between the filled 2p band and the empty 3s band is calculated as 10.07 ev, suggesting negligible intrinsic semiconduction. The width of the 2p band is 0.0625 ev, signifying that chain conformation may change easily at room temperature, for example from a right-handed helical conformation to the conformation of the opposite hand.
Secondary Electron Emission of MgO Crystals Bombarded by Relativistic Electrons
Authors: Pomerantz Martin A. , Shatas Romas A. , Schieve William C. 
Published: April 2005

The yield of single crystals of MgO has been determined at a primary energy of 1.3 Mev, utilizing a modification of the ``sandwich'' technique developed earlier for investigating the secondary electron emission of metals at high primary energies. The value of δ for Al was measured concurrently under identical conditions.
The accumulation of surface charges usually encountered with insulators is prevented by the bombardment-induced conductivity of MgO. The influence of multiple scattering and energy loss of the primary beam, as well as of δ-ray production, must be considered when the targets are relatively thick as in the present case. An empirical correction for normalizing the thick target measurements to thin target conditions was determined.
The result is: δMgO=0.09±0.02 as compared with δAl=0.023±0.003.
Direct Measurements of the Surface Energies of Crystals
Authors: Gilman John J. 
Published: April 2005

By means of quantitative cleavage experiments, the surface energies of several simple crystals have been measured at −196°C. The crystals and their cleavage planes are: LiF (100), MgO (100), CaF2 (111), BaF2 (111), CaCO3 (1010), Si (111), and Zn (0001). Measured values of their respective surface energies (ergs/cm2) are: 340, 1200, 450, 280, 230, 1240, and 105. The measured values for LiF and MgO are in good agreement with simple ionic lattice theory. Values for the other crystals seem consistent with their binding energies.
Under irreversible conditions an effective surface energy is measured. This quantity increases rapidly with increasing temperature for the metallic crystals, Zn and Fe (3% Si). The increase correlates with increasing plastic flow in these crystals. In contrast, the effective surface energy of LiF and MgO is only moderately dependent on temperature.
A small amount of cadmium (0.1 at.%) markedly increases the cleavage surface energy of zinc.
Single Crystal Tungstates for Resonance and Emission Studies
Authors: Van Uitert L. G. , Soden R. R. 
Published: April 2005

A number of single crystal tungstates have been prepared for paramagnetic resonance and emission studies. Compositions such as monoclinic MgWO4, ZnWO4, CdWO4, and tetragonal CaWO4, SrWO4, and BaWO4 containing paramagnetic ions of the transition and rare earth series have been prepared. They were grown by dissolving the constituent oxides into an equimolar mixture of Na2WO4 and WO3 at 1100 to 1250°C and cooling at 2 to 3°C per hour to 700°C.
These crystals offer the advantages of one environment for the paramagnetic ions present, freedom from strain (hardness equal to that of iron), absence of random ordering effects, minimal effects from nuclear magnetic moments, and chemical stability. Large zero field splitting are observed in the monoclinic crystals, making them of interest for studies at high microwave frequencies. The tetragonal compositions are promising at the lower microwave frequencies and have shown very narrow resonance lines. Line widthṡ as low as 1.5 Mc have been obtained in CaWO4:Mn.
Na0.5Y0.5WO4 crystals, which have the scheelite structure, were also grown. Random ordering effects of monovalent sodium and trivalent yttrium, however, result in a nonhomogeneous electrostatic environment throughout the crystals and hence cause broad paramagnetic resonance lines.
Theory of Non-Newtonian Flow. III. A Method for Analyzing Non-Newtonian Flow Curves
Authors: Kim Wan Kyue , Hirai Nishio , Ree Taikyue , Eyring Henry 
Published: April 2005

The historical development of the rate theory of viscosity is briefly reviewed. The Ree-Eyring equation of generalized viscosity, η= ∑ n=1m(xnβn/αn)(sinh−1βnṡ/βnṡ)is applied successfully in a variety of cases. (For the definitions of the symbols in this equation, reference is made to the text.) We develop here a new method for determining the parameters xn/αn and βn in Eq. (A). According to the method, these parameters are uniquely determined. When we used the parameters determined by the new method, the viscosities for solutions of poly-γ-benzyl-l-glutamate were calculated from Eq. (A). It is found that Eq. (A) is much superior to other frequently applied viscosity equations.
Upon calculating the Newtonian viscosities ηs for fairly concentrated solutions of polyacrylonitrile and of nitrated pine pulp, the following empirical formula is found: ηs≃KC2Mβp12. Here K is a characteristic constant for a solution; C the concentration; M the molecular weight; and βp is the ``principal'' relaxation time. In dilute solutions, Eq. (B) reduces to the form ηs≃K′CM.
High-Energy Sputtering
Authors: Yonts O. C. , Normand C. E. , Harrison Don E. 
Published: April 2005

Sputtering ratios for copper have been determined in the energy ranges 5–40 kev for bombardment by Ar+, He+, and D+. Argon values range from 6.48 at 5 kev to 9.25 at 27.5 kev, deuterium from 0.048 at 10 kev to 0.023 at 44 kev, and helium from 0.23 at 15 kev to 0.75 at 40 kev.
Preliminary data are included for 30-kev sputtering of copper by H+(0.011), D+(0.03), He+(0.13), N+(5.28), Ne+(3.61), Ar+(9.02), CU+(9.60), Kr+(15.15), and U+(20.9). Also included are sputtering ratios at 30 kev for Ar+ on Ta(2.7), Mo(3.31), and Al(2.38). Most of these data are the result of a single measurement, and require further verification.
A definite pressure dependence of the sputtering ratio for Ar+ on Cu was found in the range of 0.04 to 0.08 μ.
Optical Studies of the Diffraction of Water Waves by Circular and Thin Elliptic Cylinders
Authors: Barakat Richard , Barakat Robert 
Published: April 2005

By using the optical grid method the diffraction of water waves from circular and elliptic cylinders were measured and compared with theory. The scattered wave intensity S and the total energy scattered per sec per unit intensity Q were measured and the results bear out the well-known fact that for angles less than 30 deg or in the vicinity of 180 deg, one cannot separate out the scattered wave and the incident plane wave.
The optical grid method is described in detail and the advantage of its being able to measure the instantaneous field emphasized.
Dislocation Multiplication in Lithium Fluoride Crystals
Authors: Johnston W. G. , Gilman J. J. 
Published: April 2005

Experimental observations are presented of dislocation multiplication, of the defect structure left behind by a moving dislocation, and of cross-glide of individual dislocations in LiF crystals. New dislocation loops form at many different sites in the wake of a moving dislocation. These loops have the same Burgers vector as the parent dislocation but do not, in general, lie on the same atomic plane. The rate of formation of new loops depends upon the magnitude of the applied stress. Such creation of new loops leads eventually to the formation of a wide glide band.
A moving screw dislocation trails many line defects behind it that lie parallel to its direction of motion. The existence and nature of these trails and the observed dislocation multiplication can be explained in terms of a mechanism which involves the formation, by cross-glide, of jogs on a screw dislocation. This cross-glide multiplication mechanism was originally proposed by Orowan and by Koehler. It is demonstrated that cross glide occurs easily in LiF, so that this mechanism is plausible. Some interesting complications arise when jogs are formed that are longer than several atomic spacings but less than several hundred. The defect trails exert a dragging of the screw dislocations that is not negligible compared to the yield stress of a crystal.
Motion of 180° Domain Walls in Metal Electroded Barium Titanate Crystals as a Function of Electric Field and Sample Thickness
Authors: Miller Robert C. , Savage Albert 
Published: April 2005

The domain dynamics of polarization reversal in metal electroded BaTiO3 single crystals have not been adequately described in the literature. The present paper contains quantitative measurements of the velocity of the sidewise motion of 180° domain-walls in BaTiO3 crystals, most of which were electroded with 200-A thick films of Au. The wall velocity has been measured as a function of several variables including the applied electric field, the crystal thickness and the impurity content added to the crystal growth melts.
The wall velocity as a function of the field E is described by v∞ exp (−δ/E) where δ and v∞ are constants over several decades of velocity. The quantities δ and v∞ are the activation field and extrapolated wall velocity for E=∞, respectively. This field dependence of the wall velocity is the same as that reported previously for liquid electroded specimens. The thickness dependence of the wall velocity, which is through δ, is very pronounced and similar to that observed in measurements of other variables under different experimental conditions. The present data are explained in terms of a surface layer estimated to be of the order of 100-A thick. It is suggested that high fields within the surface layer may give rise to electron field emission and the electroluminescence which is observed during polarization reversal. Effects on the wall motion which persist for times of the order of minutes are ascribed to dielectric relaxation phenomena. The observed dependence of the wall motion on the impurity content of the cyrstal, and several other parameters, may result from changes in the characteristics of the surface layer.
Analysis of Composite X-Ray Diffraction Profiles
Authors: Slade J. J. , Nanni L. F. 
Published: April 2005

The irregular line profiles associated with crystals that have a random structure which is coarse relative to the irradiated area are regarded as the result of the composition of a characteristic distribution and a set of broadening and translating processes.
The inversion of this composition is expressed operationally. A differential operator associated with the transform of the intrinsic distribution is introduced. This operator reduces the line profile to the set of broadening and translating elements. The operations are such as may be performed by an analogue computer. Preliminary experiments show that it may be possible to obtain the desired resolution. The effects of ``noise'' and distortion are investigated.
Electrical Stability and Life of the Heated Field Emission Cathode
Authors: Dyke W. P. , Charbonnier F. M. , Strayer R. W. , Floyd R. L. , Barbour J. P. , Trolan J. K. 
Published: April 2005

The cold tungsten field cathode exhibits electrical stability and long life (12 000 hr demonstrated) at dc emission densities up to 107/cm2, when operated in vacuum tubes with a residual gas pressure below 10−12 mm Hg; with a provision for periodic reconditioning of the cathode surface by a brief flash heating, satisfactory operation of the cold cathode may be achieved at tube pressures up to about 10−9 mm Hg. Continuous heating of the field cathode is shown to yield useful electrical stability at conventional tube pressures, e.g., 10−6 mm Hg.
The theory of transport phenomena in heated metals is applied to a quantitative study of the geometrical stability of the heated field cathode. Expressions are derived for the time rate of change of cathode tip radius in the presence or absence of dc and pulsed electric fields at the cathode surface, and long-term geometrical stability of the cathode surface is predicted when the average applied field has the proper value. Large cathodes operated at high current level will only tolerate pulsed emission, and expressions are obtained for the maximum allowed duty cycle and pulse length in this case; small heated cathodes are capable of stable dc emission.
Occurrence of a vacuum arc is proposed as the cause of cathode failure. Considerations based on this assumption lead to predictions concerning the dependence of average cathode life on temperature, and to quantitative expressions for the statistical distribution and average value of life for unbiased field cathodes operated at high temperatures.
Experimental results yielded by the operation of 85 cathodes show good agreement with the theory. The heated cathode shows constant performance over a long period after which cathode failure occurs abruptly, and the statistical nature of cathode life is confirmed. The statistical distribution of cathode life and the measured effect of various parameters on average life show good agreement with theoretical predictions. Unbiased tungsten cathodes yielded an average life of 250 hr at an optimum cathode temperature of 2040°K. With the application of a suitable bias both long-term stability and an average life of 487 hr at 1970°K have been achieved, and according to the theory a substantial further increase in average life may be obtained by the use of a higher cathode temperature and of cathode materials with reduced impurity content.
Etch Pits at Dislocations in Copper
Authors: Livingston J. D. 
Published: April 2005

A modification of an etch discovered by Lovell and Wernick has been shown to be a reliable means of revealing dislocations as etch pits on (111) faces of copper crystals. The etch has been employed to study dislocation distributions in as-grown, annealed, and deformed crystals.
A high-temperature anneal is found to lower the dislocation density of melt-grown crystals. A ``double-etch'' technique is employed to observe the motion of dislocations, and to show that the dislocations initially present in these crystals are mobile at low stresses. Subboundaries are numerous in these crystals and are found capable of hindering dislocation movement. Observations of the dislocation structure of crystals deformed in bending and in tension are reported, including the appearance of ``glide polygonization'' after room-temperature deformation.
Dislocation Damping Effects in Rock Salt
Authors: Bauer Charles L. , Gordon Robert B. 
Published: April 2005

Internal friction measurements made as a function of strain amplitude on deformed sodium chloride single crystals were followed by elastic modulus measurements made during x irradiation of the same crystals. Etch pit densities were also determined. These data were used to evaluate the constants in a theory, proposed by Granato and Lücke in 1956, which permits the calculation of the average length of the dislocation segments, L, which vibrate under an applied alternating stress. An independent determination of the magnitude of L was made from the elastic modulus data using a method developed by Gordon and Nowick.
It is concluded that the theories tested in this paper give a useful representation of dislocation damping phenomena in sodium chloride and permit use of internal friction measurements for the continuous observation of dislocations.
pLayers on Vacuum Heated Silicon
Authors: Allen F. G. , Buck T. M. , Law J. T. 
Published: April 2005

It has been established that when silicon is heated above 1300°K in a borosilicate glass vacuum system from 1011 to 1015 acceptors per cm2 are normally added to the silicon surface, even though the glass walls remain at room temperature. The acceptor diffuses into the surface upon heating forming a p layer several microns deep.There is strong evidence that the acceptor is boron from the borosilicate glass envelope. The transfer to the silicon is believed to occur through volatilization of boron oxides by water vapor.
Production and Properties of Thin Layers of Indium Antimonide
Authors: Bate G. , Taylor K. N. R. 
Published: April 2005

A new method of producing thin layers of indium antimonide is described. This consists of suddenly squashing a drop of molten indium antimonide between two optical flats and allowing it to cool.
Large area, self-supporting specimens of 10-μ thickness have been prepared in this way and their properties examined. Although these layers are polycrystalline, their electrical and optical properties are in good agreement with the single-crystal materials from which they were obtained.
Parametric Diode Figure of Merit and Optimization
Authors: Mortenson K. E. 
Published: April 2005

The noise figure and gain expressions for the diode parametric amplifier are presented and discussed which include the effects of diode losses. From these relationships, a new diode figure of merit is defined as follows: fD=an/ 4πa02C0RD, where an is the normalized Fourier coefficient of the time dependent (pumped) capacitance; C0, the diode capacitance at the operating bias point; and RD, the equivalent series diode resistance. It is shown that this figure of merit is directly applicable in comparing diodes of various types as well as in optimizing their respective design for low-noise amplifier use. Further, it is indicated how this figure of merit can be directly employed by the circuit designer to predict an amplifiers' noise figure performance including the effects of choice of bias, pump swing, and signal and idle frequency for a given diode.A complete evaluation of the proposed figure of merit is made for the abrupt junction diode by expressing fD in terms of device design parameters and examining as a function of bias and base doping. It is concluded, if no constraints are considered, that the maximum value of fD is obtained for a bias approximately equal to half the breakdown voltage with full pump swing and that fD(max) increases with decreasing base doping from 1018 to 3·1015 atoms/cc. It is further concluded that the maximum possible value of a1/a02 for the inverse square root of voltage capacitance law is approximately 0.557 such that the greatest value fD(max) can attain is 20% of fc, the diode cutoff frequency. Some possible limitations on this evaluation are discussed including the effects of diode deviation from model, pump power or diode dissipation restrictions, nonsinusoidal pumping waveform, and ambient temperature.
Equation of State for Nineteen Metallic Elements from Shock-Wave Measurements to Two Megabars
Authors: McQueen R. G. , Marsh S. P. 
Published: April 2005

Plane-wave explosive systems were used to accelerate thin metal plates to high velocities. Shock pressures resulting from the collision of these driver plates with a stationary target plate are approximately three times greater than the original shock pressure in the driver plate. The photographic flash-gap technique was used to record velocities associated with the shock waves. The new experimental data extend the Hugoniot loci into the one-to two-megabar region for 19 metallic elements: Ag, Au, Cd, Co, Cr, Cu, Mo, Ni, Pb, Sn, Th, Ti, Tl, V, W, Zn, Bi, Fe, Sb.
The Hugoniot P, V, E data have been extended to a more complete P, V, E, T equation of state by use of the Mie-Grüneisen theory. The thermodynamic variable, γ=V(∂P/∂E)v, necessary for this extension, was obtained by solving the Dugdale-MacDonald relation.