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 Feb 1971

Volume 42, Issue 2, pp. 503-898

Page 2 of 4 Pages Previous Page Next Page | Jump to Page

Adhesion of Small Metal Spheres to Plane Metal Substrates

Douglas F. St. John and D. J. Montgomery

J. Appl. Phys. 42, 663 (1971); http://dx.doi.org/10.1063/1.1660077 (6 pages) | Cited 14 times

Online Publication Date: 15 December 2003

Full Text: | Download PDF

Show Abstract
Small metal spheres (gold and silver, diameter 5–60 μ) dusted on plane metal substrates (gold, silver, nickel, stainless steel) were removed by application of centrifugal forces or electrostatic fields. For forces applied perpendicularly outward from the substrate, the force for removal by centrifuging was found to be much larger than that for removal by electrostatic fields. Analysis of these results shows that the spheres are not to be treated as particles, but rather as elastic or plastic bodies whose adhesion to a substrate is controlled by tangential as well as normal components of the applied force. To investigate the mechanism of removal, centrifuge runs were made with the removal force applied at varying angles with the normal to the plane. The dependence of force on angle is affected by the hardness of the substrate. For relatively soft substrates, the adhesion force reaches its minimum at angles greater than 90°, that is, when the sphere is actually pushed into the substrate. This surprising result can be interpreted on the basis of a plastic‐deformation model.

Propagation of Stress Waves in a Laminated Plate Composite

C. D. Lundergan and D. S. Drumheller

J. Appl. Phys. 42, 669 (1971); http://dx.doi.org/10.1063/1.1660078 (7 pages) | Cited 17 times

Online Publication Date: 15 December 2003

Full Text: | Download PDF

Show Abstract
The dispersion of a finite, dilatational stress wave propagating in a laminated composite was investigated both experimentally and analytically. The composite consisted of ten bilaminar plates oriented so that the plane of the plates was normal to the direction of the wave propagation. A flat plate accelerated by a compressed gas gun was used to induce a planar impact. Two one‐dimensional wave‐propagation codes were used to analyze the problem and to make comparisons with the experimental results. In general, the comparisons were good, indicating one‐dimensional wave‐propagation codes can be used to describe wave propagation in composites of this configuration. The analysis indicates the need to account for the influence of fracture and the nonlinearities of the constitutive materials in the description of the transmitted stress wave.

Orientation and Temperature Dependence of the Photoplastic Effect in ZnO

Lennart Carlsson

J. Appl. Phys. 42, 676 (1971); http://dx.doi.org/10.1063/1.1660079 (5 pages) | Cited 20 times

Online Publication Date: 15 December 2003

Full Text: | Download PDF

Show Abstract
The photoplastic effect in ZnO is observed as a strong reversible increase in flow stress, during illumination with white light, when single crystals are deformed in basal slip at room temperature. An earlier model based on Read's theory for the space‐charge region near a charged dislocation has been confirmed by further measurements. Basal dislocations in the wurtzite lattice are expected to show different electrical behavior than prismatic dislocations. The basal dislocations contain atoms of the same kind in the dislocation line and are expected to be electrically active through electron trapping to dangling bonds. The prismatic dislocations have alternating kinds of atoms in the dislocation line and are expected to be electrically inactive by a possible interlock of the broken bonds. Therefore, dislocations in prismatic slip should be uncharged and show no photoplastic effect. This was confirmed by experiments showing that there is no observable effect of illumination on the flow properties when crystals are deformed in prismatic slip. The different electrical activity of the dislocations in the two slip systems is also reflected in the resistivity and photoconductivity behavior of deformed samples.

Effect of Pressure on the Fracture of Glass

Sheldon M. Wiederhorn and Harold Johnson

J. Appl. Phys. 42, 681 (1971); http://dx.doi.org/10.1063/1.1660080 (4 pages) | Cited 3 times

Online Publication Date: 15 December 2003

Full Text: | Download PDF

Show Abstract
The fracture surface energy of three glass compositions was measured as a function of hydrostatic pressure and was found to be independent of pressure to 20 kbar. This suggests that no change in the fracture mechanism occurs. The brittle behavior of glass thus differs from plastics and metals which are observed to become stronger and more ductile with increasing pressure.

Nonlinear Optical Properties of Potassium‐Lithium Niobates

A. W. Smith, G. Burns, B. A. Scott, and H. D. Edmonds

J. Appl. Phys. 42, 684 (1971); http://dx.doi.org/10.1063/1.1660081 (3 pages) | Cited 15 times

Online Publication Date: 15 December 2003

Full Text: | Download PDF

Show Abstract
Crystals of composition (K2O)0.3(Li2O)0.7‐x (Nb2O5)x with x in the range 0.515 to 0.55 have useful and unique nonlinear optical properties. These are transparent ferroelectric crystals having the tetragonal tungsten‐bronze structure. Thus, they do not have to be detwinned, as does NaBa2Nb5O15. The dc halfwave voltage is about 1350 V at 6328 A, and the nonlinear constant d31 is 1.7d31 (LiNbO3). For x=0.515 the birefringence is very large. Thus, the phase‐matching temperatures for harmonic generation without double refraction with the Nd‐YAG laser is 450°C. For x=0.55, 140°C is obtained. With these crystals the GaAs injection laser emitting 0.90 μ can be phase matched above room temperature for the first time without double refraction.

Mössbauer Characteristics of ϵ, χ, and θ Iron Carbides

Z. Mathalone, M. Ron, J. Pipman, and S. Niedzwiedz

J. Appl. Phys. 42, 687 (1971); http://dx.doi.org/10.1063/1.1660082 (9 pages) | Cited 14 times

Online Publication Date: 15 December 2003

Full Text: | Download PDF

Show Abstract
The Mössbauer effect in 57Fe has been used to study carbide phases appearing during the tempering process of an alloy steel containing 1.33 wt.% Si, 1.13% wt. Mn, and 0.38 Wt.% C. Carbides were chemically extracted from the samples which had been isothermally tempered for 2 h at various temperatures. Carbides obtained from samples tempered at 300° and 400°C were identified as ϵ and χ phases, respectively. The ϵ carbide has an isomer shift (I.S.) of 0.18 mm∕sec relative to α iron and an effective hyperfine field (Hn) of 162 kOe at 300°K. The χ carbide has an I.S. of 0.28 mm∕sec relative to α iron and Hn of 179 kOe at 300°K. Carbides precipitated at and above 500°C were found to have the orthormbic cementite structure, with a composition of (Fe1−xMnx)3C. As the tempering temperature increases from 500° to 700°C the Curie temperature changes from 440° to 270°K, and x increases from 0.02 to 0.10. Curie points and extrapolated values of Hn(0) were found for all the carbides in question. The early stages of tempering in which transition carbides appear are explained as being controlled by the elastic strain. The elastic binding energy between an interstitial carbon atom and a substitutional silicon atom can then be estimated. Other phases which were found in the chemically extracted samples after tempering the alloy at a low temperature, were identified as oxyhydeoxides and iron gel. In a sample tempered at 700°C the carbide was detected in the steel matrix and compared with the same carbide after chemical extraction.

Charge Transport and Photoconductivity in Amorphous Arsenic Trisulfide Films

S. W. Ing, J. H. Neyhart, and F. Schmidlin

J. Appl. Phys. 42, 696 (1971); http://dx.doi.org/10.1063/1.1660083 (8 pages) | Cited 23 times

Online Publication Date: 15 December 2003

Full Text: | Download PDF

Show Abstract
Charge transport and photoconductivity in As2S3 amorphous films have been investigated at a temperature of 25°C. It is found that holes are the mobile carriers in As2S3 whereas electrons are quite immobile in the material. The photoconductivity is mainly governed by the product of the photogeneration efficiency and the schubweg of the generated holes. Both of these quantities are electric field dependent. Carrier transport is essentially dominated by bulk trapping. The traps are distributed in energies above the hole conduction states. The release rate of the trapped charges varies since the rate is an inverse function of the trap energy. A theoretical model describing the transport process is presented to account for the experimental results. The photogeneration efficiency as a function of electric field at high fields (greater than 105 V∕cm) has been determined for incident photon energies of 2.5–3.1 eV. The generation efficiency is observed to decrease in the same manner as the absorption coefficient with decreasing photon energy in the light wavelength range 4000–5000 Å.

Growth Rates and Stability Limits for Beam‐Plasma Interaction

S. A. Self, M. M. Shoucri, and F. W. Crawford

J. Appl. Phys. 42, 704 (1971); http://dx.doi.org/10.1063/1.1660084 (10 pages) | Cited 34 times

Online Publication Date: 15 December 2003

Full Text: | Download PDF

Show Abstract
A treatment is given of the one‐dimensional problem of beam‐plasma interaction, including the effects of plasma and beam thermal velocities and momentum transfer collisions in the plasma. The conditions under which the Landau damping due to the plasma is negligible are first investigated. Neglecting this damping, a weak‐beam approximation to the dispersion relation is derived, and conditions for its validity are established. Expressions are derived for the maximum temporal and spatial growth rates in the limits of cold and hot beams, and few and many collisions. The growth rates given by the weak‐beam approximation are compared with those calculated from the full dispersion relation. The transition from a cold to a hot beam is discussed in terms of the topology of the roots of the dispersion relation, and also in terms of the location of the phase velocities of the most unstable waves relative to the bump in the distribution.

Electron Transmission Measurements for Al, Sn, and Au Targets at Electron Bombarding Energies of 1.0 and 2.5 MeV

D. H. Rester and J. H. Derrickson

J. Appl. Phys. 42, 714 (1971); http://dx.doi.org/10.1063/1.1660085 (8 pages) | Cited 3 times

Online Publication Date: 15 December 2003

Full Text: | Download PDF

Show Abstract
Total transmitted electron energy spectra have been constructed from measurements of electron energy spectra at various emission angles for targets of Al and Au of thicknesses of from 0.2 to 0.6 of the range in these materials. Bombarding energies of 1.0 and 2.5 MeV were used for beams of perpendicular incidence to the targets. Angular distributions of transmitted electrons are shown. At 1.0 MeV, total transmitted electron energy spectra are constructed from measurements in which incident electron beams were used to simulate an electron flux of intensity varying as the cosine of the angle of incidence. Targets of Al, Sn, and Au were used. Comparisons are made to calculated spectra from ETRAN 15 of Berger and Seltzer.

New S = 1 EPR Center in Irradiated Diamond

Y. M. Kim and G. D. Watkins

J. Appl. Phys. 42, 722 (1971); http://dx.doi.org/10.1063/1.1660086 (3 pages) | Cited 9 times

Online Publication Date: 15 December 2003

Full Text: | Download PDF

Show Abstract
Electron spin resonance studies have been made of natural diamond crystals electron‐irradiated at room temperature. A radiation‐induced spectrum is identified as arising from a new anisotropic S=1 center. The S=1 center is characterized by: g1 = 2.0026, g2 = 2.0021, g3 = 2.0016; D1 = ∓27(10−4 cm−1), D2 = ∓25(10−4 cm−1), D3 = ±51(10−4 cm−1). Associated with each resonance line are four sets of weaker lines which are ascribed to hyperfine interaction with 13C (I=☒, 1.1% abundant) at four nonequivalent sets of sites. The identity of the defect has not yet been established.

Electrical Conduction in Ferromagnetic Metal Oxide Junctions

R. K. Smeltzer

J. Appl. Phys. 42, 725 (1971); http://dx.doi.org/10.1063/1.1660087 (5 pages) | Cited 1 time

Online Publication Date: 15 December 2003

Full Text: | Download PDF

Show Abstract
The electrical conduction from 4.2°K to room temperature in thin film Ni☒NiOx‐metal junctions was studied. Tunneling is the dominant conduction mechanism at low temperature; at high temperature, Schottky thermionic emission dominates. The effective barrier thickness determines at what temperature the conductivity changes from tunneling to Schottky emission. Atomic penetration into the oxide is important, and there appear to be broad transition regions at the metal‐oxide interfaces. Using the conventional models, the barrier heights are approximately 0.2 eV.

Analysis of Impurity Distribution in Homoepitaxial n on n+ Films of GaAs which Contain High‐Resistivity Regions

J. V. DiLorenzo, R. B. Marcus, and R. Lewis

J. Appl. Phys. 42, 729 (1971); http://dx.doi.org/10.1063/1.1660088 (11 pages) | Cited 12 times

Online Publication Date: 15 December 2003

Full Text: | Download PDF

Show Abstract
The occurrence of a high‐resistivity region (i layer) at the interface of n‐type GaAs films on n+ GaAs substrates has been a recurring problem in the halide synthesis transport growth of these films for microwave devices. Consistent success in the elimination of an i layer in the doping profile has been achieved by deposition of an n+ epitaxial film substrate prior to growth of the active n film, however the nature and cause of the i layer has remained unknown. It has been proposed by others that the i layer is caused by the presence of an impurity in that region. Under this assumption, a new analytical tool, the Direct Image Mass Analyzer (DIMA, Bell & Howell∕CEC) has been used to obtain depth impurity profiles of known impurities through five homoepitaxial n‐on‐n+ GaAs film samples. These samples differed in the type of dopants used in the film and substrate, and in the magnitude of the i layers. The data were compared with doping profiles, and an analysis of this comparison has led to the following conclusions: (1) The impurities that are present in these samples include Si, K, Li, C, Na, Fe, F, Cl, and Mn; (2) the presence of an i layer is correlated with the presence of a high concentration (∼1×1021∕cm3) of silicon in the i layer region; and (3) the origin of the silicon is probably external to the sample. The hardware of the reactor is a likely source of silicon, and a mechanism is proposed for the transport of the silicon into the growing film.

I. Luminescence and Free Carrier Decay Times in Semiconductors Containing Isoelectronic Traps

J. D. Cuthbert

J. Appl. Phys. 42, 739 (1971); http://dx.doi.org/10.1063/1.1660089 (8 pages) | Cited 8 times

Online Publication Date: 15 December 2003

Full Text: | Download PDF

Show Abstract
This paper describes the measurement of free carrier decay profiles over the temperature range 7°–300°K for GaP:N, GaP:Bi, CdS:Te, and ZnTe:O following their excitation by pulses of electrons from a Van de Graaff accelerator. Contactless microwave transmission and reflectivity techniques were employed to measure the transient conductivity changes. The studies were made principally to obtain a more complete understanding of the recombination mechanisms previously proposed to be operative in CdS:Te and ZnTe:O on the basis of luminescence decay time data. The gross features of the temperature dependence of the free carrier lifetimes correlate well with the luminescence decay time data. Differential equations, formulated to describe the temperature‐dependent kinetics, were solved by a combination of numerical and analytical methods to obtain the transient luminescence and free carrier decay profiles. The solutions depend very weakly upon certain capture coefficients. The major variable parameter is in both cases the binding energy ϵ of the majority carrier in the Coulomb field of the charged isoelectronic trap. For CdS:Te, with ϵh=20 meV, good agreement was obtained between the calculated and observed free carrier and luminescence decay profiles, thereby providing good support for the model of the recombination mechanism. For ZnTe:O with ϵe=20 meV, agreement is adequate for the luminescence profiles, but only semiquantitative for the free carrier decay profiles. Reasons for the discrepancies are discussed. For all the materials, at the lowest temperatures, the results indicate very rapid and stable trapping of the carriers with no evidence of a post‐excitation conductivity. This is in keeping with the occurrence of highly radiative transitions at these temperatures.

II. Auger Electron Conductivity in Silicon

J. D. Cuthbert

J. Appl. Phys. 42, 747 (1971); http://dx.doi.org/10.1063/1.1660090 (6 pages) | Cited 6 times

Online Publication Date: 15 December 2003

Full Text: | Download PDF

Show Abstract
The contactless microwave reflectivity technique was used to measure the transient free carrier density following the creation by a pulsed electron accelerator of electron‐hole pairs in arsenic‐doped silicon at 7°K. The experiments were directed at providing supporting evidence for the Auger recombination mechanism postulated by Nelson et al. as being operative in the decay of excitons bound at neutral donors in silicon. The results contrast distinctly with the results of similar experiments on semiconductors containing isoelectronic traps by showing a strong post excitation conductivity. Differential equations, describing the model of Auger decay and including the important effects of residual acceptors, are formulated and solved numerically. At high excitation levels the theoretical profiles depend weakly on unknown capture cross‐sectional parameters and agree well with the experimental profiles. At lower excitation levels, the predicted profiles have a stronger dependence on the values of the unknown parameters, but, assuming reasonable values, good fits to the experimental data are obtained. It is therefore concluded that conductivity associated with Auger electrons has been observed.

Ultraviolet‐Enhanced Oxidation of Silicon

Ruben Oren and Sorab K. Ghandhi

J. Appl. Phys. 42, 752 (1971); http://dx.doi.org/10.1063/1.1660091 (5 pages) | Cited 31 times

Online Publication Date: 15 December 2003

Full Text: | Download PDF

Show Abstract
This paper describes the results of dry thermal oxidation of silicon under uv‐irradiation conditions. A model is proposed to explain the enhanced oxidation and reduced surface‐state charge density that occur under these conditions.

Excitation and Doping Dependences of Electron Diffusion Length in GaAs Junction Lasers

C. J. Hwang

J. Appl. Phys. 42, 757 (1971); http://dx.doi.org/10.1063/1.1660092 (5 pages) | Cited 8 times

Online Publication Date: 15 December 2003

Full Text: | Download PDF

Show Abstract
The dependence of electron diffusion length on the excitation and impurity compensation in the p region of a GaAs junction laser has been calculated from the band theory of impure semiconductors. Using a screened potential for each impurity atom, the average room‐temperature diffusion length in a typical diffused diode is found to be 1.4 μ at low injection limit. The diffusion length increases with increase in excitation because of the enhancement in carrier screening and carrier diffusion energy. This effect can be used to explain the much lower threshold current in an AlxGa1−xAs☒GaAs heterostructure laser and an abnormally high threshold current in a shallow diffused homostructure laser. Furthermore, the electron diffusion length is found to be larger for the region near the junction due to longer electron lifetime in this region. This also explains the observation that in a normal diffused junction laser, the active region occurs somewhere in the p region but not right next to the space‐charge region.

Dynamic and Steady‐State Injection of Electron‐Hole Plasma in p‐Type InSb

B. Ancker‐Johnson and Wm. P. Robbins

J. Appl. Phys. 42, 762 (1971); http://dx.doi.org/10.1063/1.1660093 (12 pages) | Cited 3 times

Online Publication Date: 15 December 2003

Full Text: | Download PDF

Show Abstract
Potential measurements as a function of time and space show in detail the passage of an injected electron‐hole plasma front, and the eventual establishment of a nonequilibrium steady state in a long bar of p‐type InSb at 77°K. The front is preceded by a depletion layer which vanishes as plasma reaches the anode. Thereafter the current, with the voltage held constant, grows exponentially until just before the steady‐state plasma density is reached. These results are compared with a theory by Dean and by Ancker‐Johnson, Robbins, and Chang describing plasma injection into a semiconductor with deep traps. The measured front arrival time as a function of constant applied voltage agrees satisfactorily with Dean's prediction. Four observations are at variance with his theory: the time constants of the exponential current growth are density‐dependent instead of being independent as predicted; the current at the front arrival is not a function of voltage as his theory states; the electric field behind the front is not proportional to the square root of distance; and the steady‐state injected current has a higher power dependence on voltage than the predicted square‐law dependence. The extended analysis accounts for all the observed growth time behavior, namely a growth time which is independent of steady‐state density at high and low densities, and which increases with density in the intermediate range. Also, a new theory of the steady‐state conduction characteristic, based on the density‐dependent plasma lifetime, reproduces quite well the measured conduction characteristics, I ∝ Vn with 2<n<8, until the interference of pinching, which causes a sub‐Ohmic conduction. In the nonequilibrium steady state the plasma density has a uniform spatial distribution within a factor of two over the central 80% of the sample length. The steady‐state density decreases monotonically from cathode to anode, or alternatively, a U‐shaped distribution is observed with high plasma densities occurring also at the anode, a characteristic which is attributed to copious hole injection. All the observed dynamic and steady‐state properties of double injection into p‐InSb are in good agreement with theory except for the constancy of the current magnitude at the front arrival and the form of the dependence of electric field on distance.

Impulse Excitation of GaP Electroluminescent Diodes

J. S. Jayson and R. W. Dixon

J. Appl. Phys. 42, 774 (1971); http://dx.doi.org/10.1063/1.1660094 (9 pages) | Cited 15 times

Online Publication Date: 15 December 2003

Full Text: | Download PDF

Show Abstract
This paper introduces an impulse technique, utilizing either electrical or optical excitation, capable of giving new information concerning the properties of luminescent systems. An analysis is included for both types of excitation and experimental results utilizing electrical excitation are reported. In particular it is shown that minority carrier lifetime in the active electroluminescent region can be evaluated directly. The technique is applied to red emitting GaP (Zn☒O) electroluminescent diodes excited with short, <2 nsec, current pulses. The resulting time‐dependent luminescent response is then interpreted using a phenomenological model previously evolved. This model assumes that bound exciton radiation dominates the luminescent process at room temperature, where the experiments were carried out. Utilization of this theory allows the extraction of several of the important parameters of the radiative and nonradiative recombination processes. Minority carrier lifetimes between 3 to 10 nsec have been deduced for particular diodes, in good agreement with values previously reported. In addition, the experimental results can be interpreted as placing an upper bound on the hole equilibration time which is sufficiently small that it permits a significant simplification of the recombination kinetics in GaP.

Effect of Various Boundary Conditions on the Instabilities in Transferred Electron Bulk Oscillators

Pradeep L. Shah and Thomas A. Rabson

J. Appl. Phys. 42, 783 (1971); http://dx.doi.org/10.1063/1.1660095 (16 pages)

Online Publication Date: 15 December 2003

Full Text: | Download PDF

Show Abstract
Transferred‐electron bulk‐negative‐differential‐conductivity devices with nonuniform geometry, field, and doping distributions are analyzed. Numerical solutions of the conduction equations was possible due to the novel scheme introduced to account for the area variation in the direction transverse to the electron flow. The simulation results show that the space‐charge travel can be controlled with the applied bias voltage for concentric and some other nonuniform geometries. This results in the possibility of tuning the frequency over two octaves. The nature of the frequency control characteristic is shown to be dependent on the device geometry. Dipole space‐charge nucleates due to nonuniform geometry without any necessity of initialization or doping fluctuations. Multiple space‐charge formation is observed to occur in an oscillation cycle as a result of sequential decay processes. Space‐charge modes in nonuniform geometries display polarity dependence. Divergent and convergent geometries are shown to favor dipole and accumulation‐type space charges, respectively. Analysis of devices with doping gradients demonstrate the equivalence of these gradients to the geometry nonuniformities. The analytical solutions of the conduction equations indicate the simple dependence of the space‐charge behavior on the geometry. The space‐charge nucleation, growth, propagation, and decay are related to the time variation of the cathode field and the domain voltage.

Tuning‐Initiated Failure in Avalanche Diodes

W. J. Evans, D. L. Scharfetter, R. L. Johnston, and P. L. Key

J. Appl. Phys. 42, 799 (1971); http://dx.doi.org/10.1063/1.1660096 (5 pages) | Cited 1 time

Online Publication Date: 15 December 2003

Full Text: | Download PDF

Show Abstract
A tuning‐initiated failure has been observed in silicon avalanche diode oscillators operated in the Trapatt mode. The precise nature of the failure mechanism remains to be established but several possibilities, based on experimental evidence, are discussed. The circuit‐tuning conditions necessary to initiate the failure (burnout) and the physical state of the diode after the failure are described. A gold whisker, which shorts the junction, is found extending from the mounting stud contact. Preliminary evidence indicates that the shape of the junction region, as controlled by the etching process, can be tailored to inhibit such diode failure.

Anomalous Electrical Properties of p‐Type Hg1−xCdxTe

Walter Scott and R. J. Hager

J. Appl. Phys. 42, 803 (1971); http://dx.doi.org/10.1063/1.1660097 (6 pages) | Cited 47 times

Online Publication Date: 15 December 2003

Full Text: | Download PDF

Show Abstract
The temperature dependence of the Hall coefficient and resistivity is presented on samples which show an anomalous behavior and the effects of various surface treatments on the electrical properties is examined. The anomalous effects have been eliminated in a few cases by proper heat treatments yielding normal p‐type Hall coefficients down to 4.2°K. Field effect measurements confirm that these effects are due to an n‐type inversion layer on the surface of p‐type Hg0.8Cd0.2Te. Surface carrier concentration in this inversion layer ranges from 1×1012∕cm2 to 5×1012∕cm2 and mobility in this layer was found to be in the 103 cm2∕V⋅sec range.

Explosion of Bare and Insulated Copper Wires

B. K. Bhat and I. B. Jordan

J. Appl. Phys. 42, 809 (1971); http://dx.doi.org/10.1063/1.1660098 (6 pages) | Cited 3 times

Online Publication Date: 15 December 2003

Full Text: | Download PDF

Show Abstract
The current waveforms obtained by exploding various sizes of copper wires by the discharge of a large condenser bank revealed that the (V, l) plane (V =initial voltage, l = length of the wire) can be divided into various zones with each zone characterising a particular type of explosion. In particular the current pause was observed only in one zone. Below a certain initial voltage no pause in the current could be induced. The restrike length of enamel insulated wires was found to be considerably more and the pause duration considerably less than for bare wires. In this case thermally emitted electrons trapped in the insulation are considered responsible for a reduction in the pause duration and an increase in the restrike length. The increased restrike current for enamel insulated wires vis a vis bare wires may be due to the arc shunting as suggested by the current wave forms obtained from exploding coils. The energy absorbed by an exploding coil depends upon its pitch.

Explosive Gas Blast: The Expansion of Detonation Products in Vacuum

Thomas J. Ahrens, Charles F. Allen, and Robert L. Kovach

J. Appl. Phys. 42, 815 (1971); http://dx.doi.org/10.1063/1.1660099 (15 pages) | Cited 8 times

Online Publication Date: 15 December 2003

Full Text: | Download PDF

Show Abstract
A series of 0.2‐ to 3‐gm HNS charges were detonated in vacuums of 10−3 to 10−5 Torr. The resultant freely expanding, detonation product, gas blast achieves terminal velocities of 8 to 12 km∕sec within 3 to 5 μsec after the detonation wave arrives at the free surface. Measured pressure profiles display rise times to maximum stagnation (``reflected shock'') pressure varying from ∼30 μsec, 20‐cm away from a 2.6‐gm charge, to ∼185 μsec, 127‐cm away from 0.2‐gm charge at 10−5 Torr. Rise times were generally shorter at 10−3 and 10−4 Torr; the 10−5 Torr values agree with numerical calculations. Using cube root scaling of charge mass, the observed peak reflected pressure as a function of range may be represented by
math
,where r′ the ratio of the range to the equivalent charge radius.

Lamb‐Mössbauer Factor of Sodium Ferrocyanide

D. L. Decker and L. E. Lortz

J. Appl. Phys. 42, 830 (1971); http://dx.doi.org/10.1063/1.1660100 (4 pages)

Online Publication Date: 15 December 2003

Full Text: | Download PDF

Show Abstract
Using a set of commercially prepared sodium ferrocyanide absorbers enriched to 91.2% Fe57 the Lamb‐Mössbauer factor was measured to be 0.28±0.03. The thickness of Fe57 for these absorbers was measured using x‐ray absorption techniques and was found to be considerably smaller than that advertised by the manufacturer even after correcting for the size of the ferrocyanide particles in the absorbers.

Resistivity and Density of Ge Films Obliquely Deposited in Vacuum

Masaru Takahashi, Hideomi Onishi, and Osamu Tada

J. Appl. Phys. 42, 833 (1971); http://dx.doi.org/10.1063/1.1660101 (4 pages) | Cited 4 times

Online Publication Date: 15 December 2003

Full Text: | Download PDF

Show Abstract
Ge films were made at 5×10−6 Torr by an oblique deposition. Resistivity and its change due to oxygen exposure were measured for different deposition angles. Resistivity anisotropy and its change caused by oxygen exposure were also measured. They increased with the deposition angle. The mass of the film was measured by a microbalance and its density was calculated. The density of the film was less than that of bulk and became smaller with an increase of the deposition angle. These phenomena are explained by the self‐shadowing effect.
Page 2 of 4 Pages Previous Page Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close