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1 Jun 1977

Volume 48, Issue 6, pp. 2117-2649

Page 1 of 4 Pages Next Page | Jump to Page

Interdiffusion in composition‐modulated copper‐gold thin films

Wayne M. Paulson and John E. Hilliard

J. Appl. Phys. 48, 2117 (1977); http://dx.doi.org/10.1063/1.324027 (7 pages) | Cited 29 times

Online Publication Date: 26 August 2008

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Vapor‐deposited Cu‐Au thin films were produced containing composition modulations with wavelengths between 8 and 26 Å. The modulations produced satellite peaks in the x‐ray diffraction patterns. Amplification factors and the corresponding diffusion coefficients were obtained by measuring the decay rate of the satellite intensities. The amplification factor reached a maximum at 17 Å and decreased at both shorter and longer wavelengths. Interdiffusion coefficients between 10−21 and 10−19 cm2/sec were measured over the temperature range 200–260 °C. The effective diffusion coefficient is linearly dependent on the function B2(λ) for λ≳10 Å. From the wavelength dependence of the measured diffusivities, a gradient‐energy coefficient of −4.7×10−6 erg/cm was obtained and is in good agreement with theoretical estimates. These experimental results were compared with the predictions from a proposed model for diffusion on cubic lattices.
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66.30.Fq Self-diffusion in metals, semimetals, and alloys
81.15.Jj Ion and electron beam-assisted deposition; ion plating
64.60.Cn Order-disorder transformations

Crystal growth: A comparison of Monte Carlo simulation nucleation and normal growth theories

J. P. van der Eerden, C. van Leeuwen, P. Bennema, W. L. van der Kruk, and B. P. Th. Veltman

J. Appl. Phys. 48, 2124 (1977); http://dx.doi.org/10.1063/1.324028 (7 pages) | Cited 6 times

Online Publication Date: 26 August 2008

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We simulated the growth of a (001) Kossel crystal surface on a special‐purpose computer. Different nearest‐neighbor bond energies in the two lateral directions of our solid‐on‐solid model were possible (anisotropy). The values which we obtained for the growth rate are much more accurate than previous results on a general‐purpose computer. The supersaturation dependence of the growth rate was compared with predictions of mean field and nucleation theories and it was shown that the latter, if properly adjusted, apply even for relatively rough surfaces. The anisotropy dependence of the growth rate was used to determine the transition from step growth to continuous growth.
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81.10.Aj Theory and models of crystal growth; physics and chemistry of crystal growth, crystal morphology, and orientation
82.60.Nh Thermodynamics of nucleation
68.35.Md Surface thermodynamics, surface energies

Weak‐shock transmission coefficient via harmonic generation

Paul Harris

J. Appl. Phys. 48, 2131 (1977); http://dx.doi.org/10.1063/1.324029 (4 pages)

Online Publication Date: 26 August 2008

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The problem of stress transmission across a boundary separating acoustically linear and nonlinear media is treated to the first order in the nonlinearity (third‐order elastic constant). The study is carried out by considering the role of harmonic generation in the nonlinear medium. An application considered is that of extending low‐ (but finite) amplitude ultrasonic measurements to the high‐pressure regime (e.g., 10 kbar) in sensitive materials such as explosives.
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43.40.+s Structural acoustics and vibration
46.40.Cd Mechanical wave propagation (including diffraction, scattering, and dispersion)
46.40.Jj Aeroelasticity and hydroelasticity
62.30.+d Mechanical and elastic waves; vibrations
62.50.-p High-pressure effects in solids and liquids

Surface study of ion‐implanted silicon wafers using SAW convolver

M. E. Motamedi, P. Das, and R. Bharat

J. Appl. Phys. 48, 2135 (1977); http://dx.doi.org/10.1063/1.324030 (4 pages) | Cited 3 times

Online Publication Date: 26 August 2008

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Nonlinear space‐charge‐coupled interaction between a surface acoustic wave (SAW) propagating on a lithium niobate substrate and ion‐implanted silicon samples placed in proximity to the SAW propagating surface has been studied. A pulsed dc electric field normal to the surface has been used to bend the surface potential for accumulation and depletion of charge carriers near the surface which in effect causes a change in attenuation of SAW. Experimental results are presented using three n‐type silicon samples into two of whcih boron was implanted. Experimental results are found to substantiate theoretical predictions of attenuation, calculated on the basis of partial compensation of the silicon doping by the implanted ions. Similar studies have also been made using incident light of varying intensity on the semiconductor surface.
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73.20.-r Electron states at surfaces and interfaces
72.50.+b Acoustoelectric effects
68.35.Gy Mechanical properties; surface strains
68.35.Iv Acoustical properties
61.72.sd Impurity concentration
61.72.sh Impurity distribution
61.72.sm Impurity gradients

Metal‐nonmetal transition in NiS under pressure

S. Anzai and K. Ozawa

J. Appl. Phys. 48, 2139 (1977); http://dx.doi.org/10.1063/1.324031 (6 pages) | Cited 11 times

Online Publication Date: 26 August 2008

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The thermodynamical model of Lidiard for an itinerant antiferromagnet is extended to involve the strain energy and the volume dependence of the energy gap between up‐ and down‐spin bands. The model is manipulated to fit the pressure effect of metal‐nonmetal transition temperature and its first‐order characteristics in NiS. Here, the volume compressibility used is measured to be 1.1×10−3 kbar−1. Changes in magnetic moment on the Ni sublattice and in enthalpy at the transition temperature are calculated from the obtained parameters and compared with the available experimental data. The nature of metal‐nonmetal transition in NiS under pressure is discussed. Present study constitutes the first attempt to understand the energetics of the metal‐nonmetal transition in NiS throughout its T‐P diagram.
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71.30.+h Metal-insulator transitions and other electronic transitions
75.50.Ee Antiferromagnetics
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
62.50.-p High-pressure effects in solids and liquids

Complex defects introduced into Si by high‐energy electron irradiation: Production rates of defects in n‐Si

Takao Wada, Kyoichiro Yasuda, Shiro Ikuta, Michihiko Takeda, and Haruho Masuda

J. Appl. Phys. 48, 2145 (1977); http://dx.doi.org/10.1063/1.324032 (8 pages) | Cited 18 times

Online Publication Date: 26 August 2008

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The n‐type silicon crystals of about 0.15, 0.9, and 10 Ω cm (pulled material) and 120 Ω cm (float‐zone material) are exposed to 2–9‐MeV electron beams at total integrated fluxes up to about 1018 electrons/cm2. The production rates of each complex defect in irradiated silicon are investigated. They are obtained from the condition of charge neutrality by using the experimental values of the resistivity as a function of bombardment dose. The electron energy dependence and the impurity density dependence of the production rate are determined for each complex defect. The results suggest that a configuration of the defect states at Ec−0.3 eV may be associated with a phosphorus atom, and in the intrinsic region the two occupied and vacant states should be symmetrically located above and below the middle of the energy gap, respectively.
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61.80.Fe Electron and positron radiation effects
61.72.jd Vacancies
61.72.jj Interstitials
66.30.Lw Diffusion of other defects

Second‐ and third‐order piezoelectric stress constants of lithium niobate as determined by the impact‐loading technique

R. A. Graham

J. Appl. Phys. 48, 2153 (1977); http://dx.doi.org/10.1063/1.324033 (11 pages) | Cited 24 times

Online Publication Date: 26 August 2008

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Determination of the e22, e33, and e15 second‐order piezoelectric stress constants, several third‐order piezoelectric stress constants, and the cD11 and cD33 elastic stiffness constants are reported for lithium niobate from experiments with input strains from 7×10−4 to 8×10−3 produced by the elastic impact‐loading method. Measurements of the e33 constant were made on a large number of samples to establish sample uniformity. The differences were found to be less than 1%. The present value of e33 is higher than that reported in previous work and appears to call for a revision of the accepted value along with that of the elastic constant cE33. The third‐order piezoelectric stress constants are readily detectable, but the values determined in the present investigation are limited in accuracy due to the relatively low strains which could be applied to the samples before conductivity became excessive.
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77.65.-j Piezoelectricity and electromechanical effects
62.50.-p High-pressure effects in solids and liquids
62.20.D- Elasticity

A study of the optically produced hexagonal pattern on ZnO single crystals

T. T. Lin and David Lichtman

J. Appl. Phys. 48, 2164 (1977); http://dx.doi.org/10.1063/1.324015 (5 pages) | Cited 1 time

Online Publication Date: 26 August 2008

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A hexagonal spot pattern (or light figure) was observed on ZnO single crystals during an Auger electron spectroscopy (AES) study. It is known that blue‐green luminescence excitation can be produced in ZnO by electron bombardment. Thus, the electron bombardment provides an alternative internal luminescence light source to produce the light figure on the etched ZnO crystals. A main feature of the electron‐induced luminescence light figure is characterized by a missing central spot. A detailed comparison of the similarities and differences between the light figure produced by electron bombardment and by illuminating with an external collimated light beam is given. An overall consistent picture between these two types of light figures can be drawn and understood on the basis of ray tracing. Though both the O polar face and Zn polar face show distinguishable etched structures, the result shows that the forming of the light pattern is mainly due to the existence of the hexagonal pyramidal etched structure on the O polar face.
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07.79.Cz Scanning tunneling microscopes
61.05.-a Techniques for structure determination
42.25.Gy Edge and boundary effects; reflection and refraction
78.60.Fi Electroluminescence

Excess vacancy generation by E‐center dissociation in the case of phosphorus diffusion in silicon

Masayuki Yoshida

J. Appl. Phys. 48, 2169 (1977); http://dx.doi.org/10.1063/1.324016 (6 pages) | Cited 15 times

Online Publication Date: 26 August 2008

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Phosphorus diffusion equations in silicon are proposed taking into account the following: Phosphorus diffuses as E centers; an E center is formed by pairing a negatively ionized vacancy with a positively ionized phosphorus atom; with increasing phosphorus concentration, the equilibrium concentration of negatively ionized vacancies increases and the ionization rate of phosphorus decreases. The equations are solved numerically under the boundary conditions of constant surface concentrations of total phosphorus atoms and negatively ionized vacancies. The phosphorus diffusion coefficient depends not only on the vacancy concentration but also on its gradient. The excess vacancies are generated by the E‐center dissociation. The concentration and the distribution of the excess vacancies are good enough to explain qualitatively the anomalous diffusion of phosphorus, except the kink in the phosphorus concentration profile.
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66.30.J- Diffusion of impurities
66.30.Lw Diffusion of other defects
61.72.jd Vacancies
61.72.jj Interstitials

Efficient bulk‐wave excitation by interdigital transducers in layered media

A. L. Nalamwar, R. S. Wagers, and M. Epstein

J. Appl. Phys. 48, 2175 (1977); http://dx.doi.org/10.1063/1.324017 (4 pages)

Online Publication Date: 26 August 2008

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Shear bulk waves multiply reflected from polished surfaces of a nonpiezoelectric substrate are efficiently excited by thin‐film ZnO interdigital transducers. Analytical results obtained using digital computations of a boundary‐value problem in a two‐layer system compare well with experimental measurements. The effect of the ZnO thin film and the shear‐bulk‐wave propagation are described.
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68.35.Gy Mechanical properties; surface strains
68.35.Iv Acoustical properties
62.65.+k Acoustical properties of solids
43.35.-c Ultrasonics, quantum acoustics, and physical effects of sound
07.07.Mp Transducers

Piezoresistive effects in ytterbium stress transducers

D. E. Grady and M. J. Ginsberg

J. Appl. Phys. 48, 2179 (1977); http://dx.doi.org/10.1063/1.324018 (3 pages) | Cited 20 times

Online Publication Date: 26 August 2008

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Ytterbium has been successfully used as the piezoresistive element in stress transducers for in situ measurements of stress amplitudes associated with wave propagation in rocks and soils and for laboratory studies of high‐rate loading effects in solids and liquids. Ytterbium has been calibrated over its useful range and it can be seen that consideration of the tensor aspects of the piezoresistance become important below 10 kbar. We have used static tensile and hydrostatic data to determine the piezoresistivity tensor coefficients and estimate the shock‐wave piezoresistance coefficient, which compares well with experiment. In addition, we offer an explanation of the difference observed between hydrostatic and shock‐wave data in the region where plastic deformation becomes important during dynamic compression.
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46.40.Cd Mechanical wave propagation (including diffraction, scattering, and dispersion)
46.40.Jj Aeroelasticity and hydroelasticity
07.07.Mp Transducers
77.65.-j Piezoelectricity and electromechanical effects
62.30.+d Mechanical and elastic waves; vibrations

Phase and amplitude relations between fundamental and second harmonic acoustic surface waves on SiO2 and LiNbO3

A. Alippi, A. Palma, L. Palmieri, and G. Socino

J. Appl. Phys. 48, 2182 (1977); http://dx.doi.org/10.1063/1.324019 (9 pages) | Cited 9 times

Online Publication Date: 26 August 2008

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The spread of results obtained by different theoretical approaches in studying acoustic surface wave nonlinear interaction and difficulties in treating strongly piezoelectric materials indicate a need for more experimental data. In the present work the spectral asymmetries of the light diffracted by surface waves are analyzed in order to evaluate the complex coupling coefficient in second harmonic surface‐wave generation. The experimental conditions are such as to keep the acoustic energy mostly confined to within fundamental and second harmonic waves. Amplitude and phase of nonlinear coupling coefficients were separately determined for LiNbO3 and crystalline SiO2 substrates through different geometries of the acousto‐optical interaction, crystal cuts, and propagation directions of the waves.
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43.25.-x Nonlinear acoustics
68.35.Gy Mechanical properties; surface strains
68.35.Iv Acoustical properties

Space‐charge effect on local electric breakdown of polyethylene at 77 K

Noriyuki Shimizu, Masamitsu Kosaki, and Kenji Horii

J. Appl. Phys. 48, 2191 (1977); http://dx.doi.org/10.1063/1.324020 (5 pages) | Cited 8 times

Online Publication Date: 26 August 2008

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The local breakdown of polyethylene adjacent to the tip of a needle electrode was studied at liquid‐nitrogen temperature. It was found from the results of the local‐breakdown voltage of various waveforms that the injected space charge from the needle electrode reduced the intense electric field at the needle tip. The injection depth of the space charge in polyethylene was assumed to be about 10 μm from the characteristic traces of the local breakdown and the light‐emitting region at the needle tip when ac voltage was applied. The electric field distribution adjacent to the needle tip was calculated by incorporating an injected space‐charge density of 3.87×10−3 C/cm3 (2.42×1016 electrons/cm3) which made the electric field strength at the needle tip equal to zero. The injected space charge modified the electric field such that the electric field strength at the edge of its distribution attained the maximum value. The results of the calculation give a reasonable explanation for the characteristic traces of the local breakdown.
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77.22.Jp Dielectric breakdown and space-charge effects
78.60.Fi Electroluminescence

Thermomigration of molten Ga in Si and GaAs

H. E. Cline and T. R. Anthony

J. Appl. Phys. 48, 2196 (1977); http://dx.doi.org/10.1063/1.324021 (6 pages) | Cited 5 times

Online Publication Date: 26 August 2008

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Molten zones of Ga have been migrated through Si and GaAs in thermal gradients between 6 and 92 °C/cm and over a temperature range between 300 and 1000 °C. The observed migration rate is larger in Si than GaAs. In both cases the droplets are faceted on (111) planes. An expression for the migration rate V is derived in terms of the solid’s heat of fusion and its solubility in the liquid. For large liquid zones, the calculated rate agrees with experiments for Ga-Si, Al-Si, and Au-Si systems. In contrast, the observed rate for the Ga-GaAs system is lower than calculated because of interface kinetics. In all systems, small liquid zones migrate slower than large liquid zones. Migration rates are also calculated for the Ag-Si, Sn-Si, Sb-Si, and In-Si systems. The general criteria for applying thermomigration in various metal-semiconductor systems are discussed.
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61.72.U- Doping and impurity implantation
66.30.J- Diffusion of impurities
81.10.Fq Growth from melts; zone melting and refining

Fluid mechanics of copper: Viscous energy dissipation in impact welding

J. L. Robinson

J. Appl. Phys. 48, 2202 (1977); http://dx.doi.org/10.1063/1.324022 (6 pages) | Cited 7 times

Online Publication Date: 26 August 2008

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The aim of this paper is twofold; to explain the parametric bounds for successful impact welding, and thereby to confirm the existence of a new region V of inviscid fluid behavior of metals. The assumption of two regions of fluid behavior (viscid and inviscid) has previously permitted a description of wave formation in impact welding and has provided an estimate of about 107 s−1 for the critical strain rate dividing the two regimes. The model is extended here to a consideration of viscous energy dissipation. It is predicted that for sufficiently high impact velocities there will be some melting, and that for sufficiently low velocities the dissipation will prevent the formation of the reentrant jet needed to remove surface impurities and permit a bond to form. In this way upper and lower bounds to a bonding region are established. Fits to data of Cu‐Cu bonding provide two estimates of the coefficient of viscosity, 102 and 2.2×102 N s m−2. These values of the critical strain rate and viscosity combine to give a critical strength of (1–2.2) ×109 N m−2. A theoretical value of 1.2×109 N m−2 lies in this range.
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62.20.-x Mechanical properties of solids
81.40.-z Treatment of materials and its effects on microstructure, nanostructure, and properties
46.35.+z Viscoelasticity, plasticity, viscoplasticity

Pyroelectricity and piezoelectricity in nylon 11

Morton H. Litt, Che‐hsiung Hsu, and P. Basu

J. Appl. Phys. 48, 2208 (1977); http://dx.doi.org/10.1063/1.324023 (5 pages) | Cited 23 times

Online Publication Date: 26 August 2008

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This paper describes preliminary pyroelectric and piezoelectric results obtained with commercial films of nylon 11. The results of dielectric‐constant measurements in the temperature range 20–130 °C are also presented. Nylon 11 films show quite high pyroelectricity and the evidence indicates that there is probably dipole orientation in crystalline regions. Charge injection or volume polarization, as well as dipole orientation, was shown to contribute to the pyroelectricity unless the sample was thoroughly relaxed.
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77.70.+a Pyroelectric and electrocaloric effects
77.65.-j Piezoelectricity and electromechanical effects
77.22.Gm Dielectric loss and relaxation

Monte Carlo calculation of electron back diffusion in a Townsend discharge

D. S. Burch and J. H. Whealton

J. Appl. Phys. 48, 2213 (1977); http://dx.doi.org/10.1063/1.324024 (4 pages) | Cited 12 times

Online Publication Date: 26 August 2008

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The back diffusion of electrons in a Townsend discharge has been analyzed by a simple Monte Carlo calculation. The problem was formulated in terms of three parameters: the ratio of molecular mass to electronic mass, the average number of collisions of an electron, and v0/vd, the ratio of emission speed to drift speed. In all cases, the back diffusion is found to be small at low values of the third parameter. It rises to a maximum and then decreases at larger values of v0/vd. For an absorbing cathode, the back diffusion is found to be predicted by the Thompson-Loeb formula with surprising accuracy, considering the approximate nature of its theoretical basis. Results are presented in a form that permits reasonable estimation of the back diffusion to be expected in experimental situations for which the parameter E/N is sufficiently high that the thermal gas motion may be neglected and sufficiently low that ionization is unimportant.
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52.80.Dy Low-field and Townsend discharges
51.50.+v Electrical properties (ionization, breakdown, electron and ion mobility, etc.)
52.20.Fs Electron collisions

Gas breakdown initiated by laser radiation interaction with aerosols and solid surfaces

David C. Smith

J. Appl. Phys. 48, 2217 (1977); http://dx.doi.org/10.1063/1.324025 (9 pages) | Cited 42 times

Online Publication Date: 26 August 2008

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The threshold for generation of high‐density plasma caused by the interaction of laser radiation with solids is examined theoretically. The developed semiquantitative model is applicable for predicting the threshold for generating laser‐supported absorption waves, absorbing plasma produced on surfaces with high‐intensity laser radiation, and also for predicting the threshold of aerosol‐induced gas breakdown, commonly referred to as dirty air breakdown. In developing the model, the vapor density generated by laser interaction with the solid is calculated and then the intensity required to cascade ionize the vapor to full ionization is calculated. Analytic expressions are derived for the breakdown intensity which show the parametric dependence of the threshold. Since the vapor density is a function of laser intensity, and characteristics of the solid, different parametric dependence of the threshold on wavelength, pulse length, and particle characteristics is predicted compared to those determined by previous theoretical models of gas breakdown. Comparison of the threshold predicted by the model agree within a factor of 2 of experimental data for a wide range of experimental conditions including laser pulse duration from 10 nsec to cw, particle sizes from 0.1 μ to laser spot sizes of 1 cm, and wavelength scaling of 1.06–10.6 μ wavelength. Based on the good agreement between theoretical predictions and experimental data, the model can be used to predict thresholds for plasma production for a wide variety of atmospheric and solid‐surface conditions.
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52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
79.20.Ds Laser-beam impact phenomena
82.70.Rr Aerosols and foams

Ion densities in a positive column He‐Cd+ laser discharge

M. Mori, K. Takasu, T. Goto, and S. Hattori

J. Appl. Phys. 48, 2226 (1977); http://dx.doi.org/10.1063/1.324026 (5 pages) | Cited 10 times

Online Publication Date: 26 August 2008

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By combining the modified absorption method with the modified double‐probe method, the He+ and Cd+ ion densities in a cataphoresis type of positive column He‐Cd+ laser discharge were separated without using the Cd+ ion mobility. They agreed with the He+ and Cd+ ion densities calculated on the basis of the electron energy distribution function in the He‐Cd discharge well.
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42.55.Lt Gas lasers including excimer and metal-vapor lasers
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.70.Ds Electric and magnetic measurements
52.80.Hc Glow; corona

A mathematical model for calculating electrical conditions in wire‐duct electrostatic precipitation devices

Jack R. McDonald, Wallace B. Smith, Herbert W. Spencer III, and Leslie E. Sparks

J. Appl. Phys. 48, 2231 (1977); http://dx.doi.org/10.1063/1.324034 (13 pages) | Cited 61 times

Online Publication Date: 26 August 2008

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A new method is developed which can be used to calculate electrical conditions in wire‐duct electrostatic precipitation devices. The method, based upon a numerical solution to the governing differential equations under a suitable choice of boundary conditions, accounts for the effect of space charge and is applicable over the entire range of current and voltage before sparkover. The procedure yields voltage‐current characteristics and determines the electric potential and electric field strength as functions of position for each current and applied voltage. Predictions of the theory are compared with existing experimental data and the agreement is excellent.
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85.50.-n Dielectric, ferroelectric, and piezoelectric devices
41.20.Cv Electrostatics; Poisson and Laplace equations, boundary-value problems
41.20.Gz Magnetostatics; magnetic shielding, magnetic induction, boundary-value problems
52.80.Hc Glow; corona

Secondary electron emission from solid hydrogen and deuterium resulting from incidence of keV electrons and hydrogen ions

H. Sørensen

J. Appl. Phys. 48, 2244 (1977); http://dx.doi.org/10.1063/1.324035 (8 pages) | Cited 13 times

Online Publication Date: 26 August 2008

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The secondary electron emission (SEE) coefficient δ was measured for solid hydrogen and deuterium resulting from the normal incidence of 0.5–3‐keV electrons and 4–10‐keV H+, H2+, H3+, and D3+ ions. The SEE coefficients for solid hydrogen are 60–70% of those for solid deuterium, and the coefficients are small, in contrast to what is expected for insulating materials. One explanation is that the secondary electrons lose energy inside the target material by exciting vibrational and rotational states of the molecules, so that the number of electrons that may escape as secondary electrons is rather small. The losses to molecular states will be largest for hydrogen, so that the SEE coefficients are smallest for solid hydrogen, as was observed. For the incidence of ions, the values of δ for the different molecular ions agree when the number of secondary electrons per incident atom is plotted versus the velocity or the stopping power of the incident particles. Measurements were also made for oblique incidence of H+ ions on solid deuterium for angles of incidence up to 75°. A correction could be made for the emission of secondary ions by also measuring the current calorimetrically. At largest energies, the angular dependence corresponds to δ (ϑ) =δ (ϑ)(cosϑ)−1.
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79.20.Hx Electron impact: secondary emission
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
34.80.Gs Molecular excitation and ionization

Particle heating in a radio‐frequency plasma torch

Toyonobu Yoshida and Kazuo Akashi

J. Appl. Phys. 48, 2252 (1977); http://dx.doi.org/10.1063/1.324036 (9 pages) | Cited 69 times

Online Publication Date: 26 August 2008

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A numerical model was developed to predict the behavior of a particle in a radio‐frequency (rf ) plasma. The analysis obtained the heat, mass, and momentum transfer of a single particle injected into an rf plasma. The governing equations for vaporization of a liquid particle were taken from the model which was used to simulate the vaporization process of liquid droplets in a rocket combuster. All the thermodynamical and transport properties were calculated as functions of temperature in order to simulate the actual behavior more precisely. The boundary conditions are a finite temperature at the particle center and a heat balance at the particle surface. Thermodynamical equilibrium at the particle surface was always assumed. ’’Moving‐boundary problems’’ in the case of melting or vaporizing processes were solved by the use of a ’’moving grid system’’. Four sizes of iron particles injected into the rf argon plasma have been computed: r0=20, 40, 60, and 80 μ. The iron particles with radii less than 70 μ could be melted under the assumed plasma conditions. It was found that the potentiality as concerns powder processing of an rf plasma was overestimated by previous models.
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52.50.Gj Plasma heating by particle beams
52.75.Hn Plasma torches
52.25.Fi Transport properties

Molecular‐beam sampling of a hollow‐cathode discharge in argon as a plasma diagnostic and a source for fast neutrals

P. G. A. Theuws, H. C. W. Beijerinck, D. C. Schram, and N. F. Verster

J. Appl. Phys. 48, 2261 (1977); http://dx.doi.org/10.1063/1.324037 (9 pages) | Cited 9 times

Online Publication Date: 26 August 2008

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Velocity analysis of the molecular beam is done with a time‐of‐flight method. The measured velocity distribution of the fast neutral atoms is described by the sum of two Maxwell‐Boltzmann distributions with temperatures on the order of 0.25 and 1 eV, respectively. This bimodal distribution is attributed to an overpopulation of the high‐energy tail of the ion velocity distribution. The measured intensities of the fast neutrals vary between 5×1014 and 7×1015 (molecules s−1 sr−1).
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52.70.Nc Particle measurements
34.50.Lf Chemical reactions
52.80.Vp Discharge in vacuum
34.50.-s Scattering of atoms and molecules

Time‐dependent plasma temperature measurements of the high‐pressure sodium arc

T. H. Rautenberg and P. D. Johnson

J. Appl. Phys. 48, 2270 (1977); http://dx.doi.org/10.1063/1.324038 (4 pages) | Cited 8 times

Online Publication Date: 26 August 2008

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The plasma temperature of the high‐pressure sodium arc has been measured as a function of time and power input on 60‐Hz sine‐wave operation. A maximum temperature of 4370 °K is found at power input above about 100 W/cm3 of arc tube volume. At zero current the temperature falls to 3300 ° K. Square‐wave operation indicates that temperature decay to this value occurs in 0.3 msec. Since local thermodynamic equilibrium (LTE) exists in the hot central core of the plasma, the electron density can be calculated using the Saha equation to decay from 1016 to 1015 cm−3 during this period. This decay in electron density is accompanied by an increase of arc reignition voltage of more than a factor of 4.
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52.25.Kn Thermodynamics of plasmas
52.80.Mg Arcs; sparks; lightning; atmospheric electricity

Plasma influence in tantalum sputtering

Y. Chouan and D. Collobert

J. Appl. Phys. 48, 2274 (1977); http://dx.doi.org/10.1063/1.323960 (6 pages) | Cited 4 times

Online Publication Date: 26 August 2008

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The angular distribution function (ADF) and the sputtering yield have been measured in a triode sputtering system where a dense ionic current (35 mA/cm2) drawn from an argon plasma confined by a magnetic field impinges upon a tantalum target biased at 1.8 keV. The system was placed in a vacuum chamber at a pressure on the order of 10−4 Torr. The results are the following for the two phases of Ta deposited. For α‐Ta the ADF is Lambertian but the associated yield is lower than the theoretical one; for β‐Ta the ADF curve lies below the Lambertian cosine curve. We suggest the following interpretation based on the influence of impurities. For α‐Ta there are many impurities which can be ionized and contribute to the current. Also, these ions destroy the Ar∗ metastables and, therefore, lower the Ta‐Ar∗ collision probability. For β‐Ta there are no impurities. The current is due only to ionized argon and Ar∗ metastables are not destroyed (i.e., the collision probability is much higher). In such a way, we are able to explain the discrepancies observed in these two cases in terms of both the sputtering yield and the ADF.
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79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
52.20.Hv Atomic, molecular, ion, and heavy-particle collisions
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
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