jap banner
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

SECTION LISTING

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

1 May 1961

Volume 32, Issue 5, pp. 755-964

Page 1 of 2 Pages Next Page | Jump to Page

End Effect Losses in dc Magnetohydrodynamic Generators

Roland A. Boucher and Dennis B. Ames

J. Appl. Phys. 32, 755 (1961); http://dx.doi.org/10.1063/1.1736100 (5 pages) | Cited 4 times

Online Publication Date: 11 June 2004

Full Text: | Download PDF

Show Abstract
In this paper the end effect loss in a dc magnetohydrodynamic generator with rectangular cross section is considered. The case for nonconducting walls is examined, and a simple expression for the losses in terms of the maximum power output is obtained. The end effect loss is compared to viscous and turbulent flow losses and it is shown to be the predominant loss over a wide range of operating conditions.

Temperature Dependence of Rolling Textures in High‐Purity Silver

Hsun Hu and R. S. Cline

J. Appl. Phys. 32, 760 (1961); http://dx.doi.org/10.1063/1.1736101 (4 pages) | Cited 17 times

Online Publication Date: 11 June 2004

Full Text: | Download PDF

Show Abstract
A rolling texture transition from the (110) [112] common silver type to the (123) [412] copper type was produced in high‐purity silver by changing the temperature of deformation. The texture determined at 0°C for a strip rolled at 0°C was a simple (110) [112]. Rolling at 200°C produced a texture of the (123) [412] type, plus a cube texture component due to partial recrystallization. Our results also suggest that the relatively high oxygen content in common silver is probably not responsible for the formation of the (110) [112] texture. The change in texture from one type to the other in high‐purity silver can be obtained by merely varying the rolling temperatures.

Stability of Pressure‐Supported Molten Zones in Horizontal Sheets

H. P. Kramer, B. P. Bogert, and D. W. Hagelbarger

J. Appl. Phys. 32, 764 (1961); http://dx.doi.org/10.1063/1.1736102 (5 pages) | Cited 1 time

Online Publication Date: 11 June 2004

Full Text: | Download PDF

Show Abstract
It is shown that the stability limit for pressurized horizontal floating zones is related to the eigenvalues of a membrane of the same shape. In particular, a rectangle of length a and width b is stable if
math
,and a circle of radius R is stable if
math
,where ρ is the density, g is the acceleration of gravity, γ is the surface tension constant, and β11=3.8317 is the first root of the Bessel function J1(x). This latter case checks with experiments on melted circular zones of tin.

Calculation of the Maximum Efficiency of the Thermionic Converter

John H. Ingold

J. Appl. Phys. 32, 769 (1961); http://dx.doi.org/10.1063/1.1736103 (4 pages) | Cited 7 times

Online Publication Date: 11 June 2004

Full Text: | Download PDF

Show Abstract
A theoretical analysis of the efficiency of a thermionic converter is made in terms of the following parameters: Va, the potential difference between the top of the potential barrier in the interelectrode space and the Fermi level of the anode; VL, the potential drop across a load impedance in series with the converter; and Vl, the potential drop in the necessary electrical connection to the cathode. The analysis is carried out by developing an expression for the efficiency of the converter and then maximizing this expression with respect to VL and Vl. This method yields optimum values of load impedance, cathode lead geometry, and cathode work function in terms of Va, cathode temperature, cathode emission constant (usually denoted by A), and effective emissivity of the cathode. A hypothetical example is worked out numerically and the results show that (1) a low value of Va is required for high efficiency, and (2) relatively low values of cathode work function are required for maximum efficiency at ordinary cathode temperatures.

Creep Behavior of Pore‐Free Polycrystalline Aluminum Oxide

Robert C. Folweiler

J. Appl. Phys. 32, 773 (1961); http://dx.doi.org/10.1063/1.1736104 (6 pages) | Cited 72 times

Online Publication Date: 11 June 2004

Full Text: | Download PDF

Show Abstract
Creep in pore‐free polycrystalline aluminum oxide has been studied as a function of temperature, grain size, and strain rate. The behavior may be described byσαd2math, where d is the mean grain diameter. Deformation is not controlled by basal slip but by a diffusional creep process as described by Nabarro and Herring, [F. R. N. Nabarro, Conference on Strength of Solids (The Physical Society, London, 1948), p. 75; C. Herring, J. Appl. Phys. 21, 437 (1950)].

Stacking Fault Probability of Noble Metal‐Zinc Alloys

L. F. Vassamillet

J. Appl. Phys. 32, 778 (1961); http://dx.doi.org/10.1063/1.1736105 (5 pages) | Cited 29 times

Online Publication Date: 11 June 2004

Full Text: | Download PDF

Show Abstract
The stacking fault probability has been measured by x‐ray means on a number of alloys of gold, silver, and copper with varying zinc content. By using these probabilities, the relative magnitudes of the stacking fault energies have been deduced.

Investigation of the Sputtering of Silicon

S. P. Wolsky and E. J. Zdanuk

J. Appl. Phys. 32, 782 (1961); http://dx.doi.org/10.1063/1.1736106 (5 pages) | Cited 9 times

Online Publication Date: 11 June 2004

Full Text: | Download PDF

Show Abstract
A sensitive vacuum microbalance was used to determine the sputtering yields for the argon‐silicon system over an energy range of 34–800 ev. Preliminary data for the ion bombardment of silicon with CO2 was also obtained. Variation of the discharge voltage provided information on the relative sputtering effectiveness of Ar+ and Ar2+ ions. Extrapolation of the low‐energy data indicates a probable threshold energy of 15–20 ev. The sputtering data indicate that the target surfaces were clean and reproducible. The experimental method is shown to be well suited for sputtering studies.

Sintering Crystalline Solids. I. Intermediate and Final State Diffusion Models

R. L. Coble

J. Appl. Phys. 32, 787 (1961); http://dx.doi.org/10.1063/1.1736107 (6 pages) | Cited 290 times

Online Publication Date: 11 June 2004

Full Text: | Download PDF

Show Abstract
Photomicrographs of pore and grain boundary structures in sintered powder compacts are presented to provide the basis for qualitative description of the important phases of the course of densification. From this guide, appropriate grain shapes and pore shapes and locations are selected for the formulation of diffusion sintering models. The principle models presented are for bulk diffusion transport with the grain boundaries as vacancy sinks when the pore phase is continuous and coincident with three grain edges, and also when the pore phase is discontinuous and located at four‐grain corners. These models predict that the rate of density change is constant when the diffusion coefficient and grain size are constant. The need for simultaneous isothermal densification and grain growth data is indicated. The explicit change in densification rate with discontinuous grain growth is predicted in terms of pore spacing and grain size.

Sintering Crystalline Solids. II. Experimental Test of Diffusion Models in Powder Compacts

R. L. Coble

J. Appl. Phys. 32, 793 (1961); http://dx.doi.org/10.1063/1.1736108 (7 pages) | Cited 206 times

Online Publication Date: 11 June 2004

Full Text: | Download PDF

Show Abstract
During sintering in alumina powder compacts, the density has been found to increase linearly with the logarithm of time, and the grain size increases with the one‐third power of time. Incorporation of the time dependence of grain size increase into latestage bulk diffusion sintering models (from Part I) [R. L. Coble, J. Appl. Phys. 32, 787 (1961)] leads to corrected models by which a semilogarithmic behavior is predicted. The presence of density gradients in normally fabricated pellets makes impossible the deduction of whether theoretical density will be achieved from the early stages of the course of densification. Diffusion coefficients calculated from the intermediate and later stages of sintering bear order‐of‐magnitude agreement with those calculated from the initial‐stage sintering measurements in alumina. All diffusion coefficients from sintering data are higher than Kingery's measured diffusion coefficients for oxygen. It is hypothesized that the sintering process must then be controlled by bulk diffusion of aluminum ions while the oxygen transport takes place along the grain boundaries. In controlling the sinterability of alumina to theoretical density, it appears that magnesia does not ``inhibit'' discontinuous grain growth, but instead increases the sintering rate such that discontinuous growth nuclei do not have time to form.

Influence of Conductivity Gradients on Galvanomagnetic Effects in Semiconductors

R. T. Bate and A. C. Beer

J. Appl. Phys. 32, 800 (1961); http://dx.doi.org/10.1063/1.1736109 (6 pages) | Cited 24 times

Online Publication Date: 11 June 2004

Full Text: | Download PDF

Show Abstract
An approximate solution is found of a boundary‐value problem arising from the continuity equation in an inhomogeneous semiconductor, leading to rotational current vectors. Results are used to predict the effect of carrier‐concentration gradients on magnetoresistance. The predicted weak‐field effects are especially significant in degenerate semiconductors and n‐type III–V intermetallics where the ``intrinsic'' magnetoresistance is small. In strong fields, even small gradients in carrier concentration can completely alter the field dependence of the magnetoresistance. Experimental results indicate that transverse currents, which do not occur in the simple case discussed, do appear in general, and further perturb the magnetoresistance. The influence of inhomogeneous magnetic fields is discussed briefly.

Influence of Magnetoconductivity Discontinuities on Galvanomagnetic Effects in Indium Antimonide

R. T. Bate, J. C. Bell, and A. C. Beer

J. Appl. Phys. 32, 806 (1961); http://dx.doi.org/10.1063/1.1736110 (9 pages) | Cited 31 times

Online Publication Date: 11 June 2004

Full Text: | Download PDF

Show Abstract
Anomalous galvanomagnetic effects associated with spatial discontinuities in carrier concentration have been observed in n‐type InSb. These discontinuities result from anisotropic segregation of impurities during crystal growth. An increase in the magnitude of the Hall coefficient at 20 000 gauss to nearly twice the weakfield value was observed in one case. The magnetoresistance is especially sensitive to inhomogeneities. For an inhomogeneous sample at a particular magnetic field, the measured Δρ∕ρ0 may be as much as 100 times larger than that for a homogeneous sample. Negative magnetoresistance has also been observed at room temperature in inhomogeneous samples. All of the above observations are predicted qualitatively by considering a simple model consisting of a long, thin specimen having a discontinuity in resistivity and Hall coefficient in the current direction. The boundary value problem corresponding to this case is solved to predict the electric field and current densities.

Shift of the Shadow Boundary and Scattering Cross Section of an Opaque Object

S. I. Rubinow and Joseph B. Keller

J. Appl. Phys. 32, 814 (1961); http://dx.doi.org/10.1063/1.1736111 (7 pages) | Cited 15 times

Online Publication Date: 11 June 2004

Full Text: | Download PDF

Show Abstract
When a wave of wavelength λ is incident upon an opaque object of typical dimension a, a shadow is formed in the geometric optics limit λ∕a=0. If λ∕a is small and not zero, the shadow boundary is shifted slightly from the geometrical shadow boundary as was first shown by Artmann. He found the shift to be asymptotic to α(λ2a)⅓ for a circular cylinder, where α is positive or negative according as the field or its normal derivative vanishes on the cylinder. The same result was obtained by Rice for a parabolic cylinder, but for the hard cylinder his α differed from Artmann's. We have redetermined α for the circular cylinder and found it to agree with the result for the parabolic cylinder in both cases. We have also determined the shift for a circular cylinder on which the field satisfies an impedance boundary condition. The former result is implicit in the work of Goriainov and both results are implicit in the work of Wait and Conda. We have also determined the scattering cross section of a circular cylinder with an impedance boundary condition. These results lead us to propose two formulas, one for the shift of the shadow boundary and one for the scattering cross section, of any smooth two‐ or three‐dimensional object. The latter expresses the deviation from the geometrical optics cross section as an integral, around a normal section of the shadow, of a multiple of the shift. This formula is verified for a sphere and for oblique incidence on a circular cylinder. Both electromagnetic and scalar waves are considered.

Induction‐Coupled Plasma Torch

Thomas B. Reed

J. Appl. Phys. 32, 821 (1961); http://dx.doi.org/10.1063/1.1736112 (4 pages) | Cited 143 times

Online Publication Date: 11 June 2004

Full Text: | Download PDF

Show Abstract
A new method of generating a stable plasma at atmospheric pressure using inductive coupling at a frequency of several Mc is described. Methods of starting and operating this plasma in argon, and mixtures of argon with helium, hydrogen, oxygen, and air are discussed. The Fowler and Milne method was used to measure the temperature profile of the plasma under various conditions of gas flow and composition, and at several power levels. Measured peak temperatures ranged from 14 000°–19 000°K. The power losses from the plasma in the form of convection, radiation, and conduction to the nozzle walls were measured under the same conditions. Total power transferred to the plasma ranged from 1.6–3.1 kw which was approximately 50% of the input power. The extent to which local thermal equilibrium prevails in the plasma is discussed; the available evidence indicates that under the operating conditions described herein, equilibrium is closely approached.

Use of PrCl3 in a Solid State Infrared Quantum Counter

John F. Porter

J. Appl. Phys. 32, 825 (1961); http://dx.doi.org/10.1063/1.1736113 (2 pages) | Cited 6 times

Online Publication Date: 11 June 2004

Full Text: | Download PDF

Show Abstract
A survey of the salts of the rare‐earth series shows that anhydrous PrCl3 has energy levels and selection rules suitable for use in a solid state infrared quantum counter as proposed by Bloembergen [N. Bloembergen, Phys. Rev. Letters 2, 84 (1959)]. Two suitable schemes are proposed, one for detection at 2.33 μ and a second for detection at 104 μ. Consideration is given to isolation of the final detector from the pumping signal and a suitable experimental arrangement for unambiguously determining proper operation is shown.

Effect of Neutron Irradiation on the Plastic Deformation of Copper Single Crystals

I. G. Greenfield and H. G. F. Wilsdorf

J. Appl. Phys. 32, 827 (1961); http://dx.doi.org/10.1063/1.1736114 (13 pages) | Cited 54 times

Online Publication Date: 11 June 2004

Full Text: | Download PDF

Show Abstract
Copper single crystals subjected to a neutron dose of 3×1018 nvt (total flux) at pile temperature have been examined after deformation by the following experimental techniques: (a) observation of the load‐extension relationships, (b) investigation of the slip‐line structure with the electron microscope, and (c) diffraction electron microscopy of thinned‐down single crystals before and after deformation. The critical resolved yield stress is in the order of 1.6 kg∕mm2. In the early stages of deformation, the load‐extension curves show serrations which are as large as 1.0% of the critical resolved shear stress. In the linear portion of the stress‐strain curve, the rate of work hardening is less for irradiated single crystals than for the nonirradiated. The stress‐strain curves of the irradiated and the nonirradiated specimens are similar in the parabolic region of the curves. The slip‐line structure, at low deformations, consists of fine slip lines that are clustered together; the distances between the slip lines are, on the average, 100 A and often less; the distances between the clusters are in the order of 4μ. This structure is quite different than the alpha‐brass structure, which in the past had been considered typical for irradiated copper. Cross slip, which is most abundant in the linear hardening region of the stress‐strain curve, is found to be orientation dependent. The slip‐line structures for the irradiated and nonirradiated crystals at high strains are very similar. Prismatic dislocation loops, apparently resulting from the condensation of vacancies, are found to be the most frequently produced radiation defect. The interaction between loops and glide dislocations results in heavily kinked dislocations which are probably responsible for the observed high yield stress. The glide dislocations were seen to remove the radiation damage. Because of this cleaning out of radiation‐produced defects and the ability of the dislocations to multiply from new sources, the prolonged ``easy glide range'' can be explained. Further, the proposed mechanism provides an explanation of the work hardening in the linear and parabolic parts of the stress‐strain curve.

Self‐Diffusion in Silver during Plastic Deformation in Torsion

J. B. Darby, C. T. Tomizuka, and R. W. Balluffi

J. Appl. Phys. 32, 840 (1961); http://dx.doi.org/10.1063/1.1736115 (9 pages) | Cited 4 times

Online Publication Date: 11 June 2004

Full Text: | Download PDF

Show Abstract
Self‐diffusion of Ag110 in silver polycrystals subjected to simultaneous torsion was studied near 700° and 800°C using the sectioning technique. Strains ⩽ 0.50 and strain rates ⩽ 13.8×10−5 sec−1 were employed. Specimen structures before and after deformation were also examined. The effects of straining on diffusion were relatively small in all cases. At 800°C the diffusivity was increased by no more than ∼50%. At 700°C the increase was no more than ∼100%. A substantial part of this observed enhancement was undoubtedly only apparent and due to difficulties associated with surface roughness. The results agreed generally with our previous work involving deformation in extension and compression but were in marked disagreement with recent results of Lee and Maddin and Forestieri and Girifalco [C. H. Lee and R. Maddin, Trans. AIME 215, 397 (1959); A. F. Forestieri and L. A. Girifalco, J. Phys. Chem. Solids 10, 99 (1959)], who have reported enhancements larger by one to two orders of magnitude. No simple explanation for these differences was found. Estimates of dislocation short‐circuiting and the generation of extra point defects indicated that only small enhancements should be expected in agreement with the present results.

Some Experiments Using a Vacuum‐Cleaned Silicon p‐n Junction

J. T. Law

J. Appl. Phys. 32, 848 (1961); http://dx.doi.org/10.1063/1.1736116 (8 pages) | Cited 5 times

Online Publication Date: 11 June 2004

Full Text: | Download PDF

Show Abstract
Measurements of the junction characteristics and the transport properties on either side of a vacuum‐cleaned silicon p‐n junction have been carried out. The changes in these properties during the adsorption of oxygen and hydrogen have also been investigated. In the clean condition, the value of (EF−EV) for both 21.5 ohm‐cm n type and 27 ohm‐cm p type was found to be 0.13–0.14 ev. When the silicon surface was clean, a large excess current across the junction was observed which disappeared during the adsorption of gas.

Distribution Coefficients of Impurities in Gallium Antimonide

R. N. Hall and J. H. Racette

J. Appl. Phys. 32, 856 (1961); http://dx.doi.org/10.1063/1.1736117 (1 page) | Cited 28 times

Online Publication Date: 11 June 2004

Full Text: | Download PDF

Show Abstract
Distribution coefficients of several column 2, 4, and 6 elements in GaSb are reported, and some of the physical properties of this material are discussed briefly.

First Magnetocrystalline Anisotropy Constants of Some Iron‐Silicon Alloys

Sigurds Arajs, Henry Chessin, and D. S. Miller

J. Appl. Phys. 32, 857 (1961); http://dx.doi.org/10.1063/1.1736118 (3 pages) | Cited 5 times

Online Publication Date: 11 June 2004

Full Text: | Download PDF

Show Abstract
First magnetocrystalline anisotropy constants K1∞ of 3.6, 6.7, 8.8, and 12.4 wt% silicon in iron alloys have been measured at 77°K and 297°K by determining the torque exerted on {100} single‐crystal disks in uniform magnetic fields. The following results on disordered alloys have been obtained:
math
The measurements of this investigation are compared with the previously known studies. The agreement, where an overlap occurs, is satisfactory.

Interaction of Slow Electrons with Insulating Crystals. I. Absorption Coefficient for Cleaved Alkali Halides; Experimental Techniques

C. J. Cook and William J. Fredericks

J. Appl. Phys. 32, 860 (1961); http://dx.doi.org/10.1063/1.1736119 (7 pages) | Cited 4 times

Online Publication Date: 11 June 2004

Full Text: | Download PDF

Show Abstract
Techniques have been developed that will permit a unique determination of an absorption coefficient δa for 0.2‐ to 20‐ev electrons on cleaved, insulating crystals. Two classes of electron trapping levels, one that empties rapidly and one that does not empty at room temperature, may exist in the target and if they do, effects caused by them may perturb the data. Experimental techniques were developed to compensate for each characteristic effect. Pure and nonstoichiometric KBr and KCl crystals were studied. The probability that a crystal‐incident electron results in a charge influx was found to vary makedly as a function of the impact energy and in a manner characteristic of the target. This feasibility study indicates that slow electron beams could be a powerful tool for diagnosing surface and bulk properties of insulating crystals.

Cross‐Doping Agents for Rutile Masers

P. F. Chester

J. Appl. Phys. 32, 866 (1961); http://dx.doi.org/10.1063/1.1736120 (3 pages) | Cited 29 times

Online Publication Date: 11 June 2004

Full Text: | Download PDF

Show Abstract
The EPR spectra of nonstoichiometric rutile and rutile doped with tantalum, niobium, and cerium have been examined at helium temperatures. Ta4+ and Nb4+ have short spin‐lattice relaxation times and appear to be suitable for cross doping in maser applications.

Electron Microscope Study of Radiation Damage in Graphite

W. Bollmann

J. Appl. Phys. 32, 869 (1961); http://dx.doi.org/10.1063/1.1736121 (8 pages) | Cited 20 times

Online Publication Date: 11 June 2004

Full Text: | Download PDF

Show Abstract
Neutron‐induced defects in the graphite lattice are studied by dark‐field transmission electron microscopy. The annealing is followed and the appearance of the defects is interpreted on the basis of the kinematical theory of electron diffraction. A physical interpretation of the observations based on displacement spikes and their annealing is given.

Textural Properties of Germanium Films

John E. Davey

J. Appl. Phys. 32, 877 (1961); http://dx.doi.org/10.1063/1.1736122 (4 pages) | Cited 18 times

Online Publication Date: 11 June 2004

Full Text: | Download PDF

Show Abstract
The textural properties of thin germanium films vacuum evaporated onto hot fused‐quartz substrates have been investigated in detail over the temperature range from ambient to 650°C. The strongest texture characteristic of these films is the [110], which is obtained at substrate temperatures as low as 175°C, and prevails up to about 350°C. For temperatures between 350° and 575°C, competition for growth occurs and the texture varies principally between being powder, [110] and [111]. Above 575°C the [111] texture becomes dominant.

Effect of Magnetic Clusters on the Specific Heat of Ni‐Cu and Fe‐V Alloys

K. Schröder

J. Appl. Phys. 32, 880 (1961); http://dx.doi.org/10.1063/1.1736123 (3 pages) | Cited 63 times

Online Publication Date: 11 June 2004

Full Text: | Download PDF

Show Abstract
Recent experiments with Ni‐Cu and Fe‐V alloys indicate that the specific heat at low temperature cannot be described by electronic and lattice terms alone. An attempt is made to explain an additional term in the specific heat of these alloys on the basis of ferromagnetic clusters.

Vacuum‐Ultraviolet Absorption Studies of Irradiated Silica and Quartz

C. M. Nelson and R. A. Weeks

J. Appl. Phys. 32, 883 (1961); http://dx.doi.org/10.1063/1.1736124 (4 pages) | Cited 20 times

Online Publication Date: 11 June 2004

Full Text: | Download PDF

Show Abstract
The optical absorption properties of Co60‐irradiated fused silica and crystalline quartz have been studied in the vacuum‐ultraviolet region. The most prominent absorption band found in both materials has a maximum at 7.6 ev (1620 A). Optical and thermal bleaching experiments indicate that this band is not necessarily complementary to a band at 5.9 ev (2100 A), as has been assumed. Though the 7.6‐ev band has approximately the same intensity in both materials for the same irradiation, the 5.9‐ev band is >20 times more intense in fused silica. The 7.6‐ev band is still present after the 5.9‐ev band has been thermally bleached. Additional absorption bands occur at 8.0 and 8.2 ev. Also, optical and thermal bleaching experiments suggest other absorption bands at 7.2, 7.4, 7.8, and 7.9 ev. Since these bands (particularly the 7.6‐, 8.0‐, and 8.2‐ev bands) occur in high‐purity silica and quartz, it is suggested that they are associated with defects in the quartz structure and are not caused by impurities.
Page 1 of 2 Pages Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close