Fractal and Non-Fractal Surfaces in Ion Sputtering

MRS Proceedings ◽

10.1557/proc-407-259 ◽

1995 ◽

Vol 407 ◽

Author(s):

A.-L. Barabási ◽

R. Cuerno

Keyword(s):

Nonlinear Equation ◽

Penetration Depth ◽

Experimental Studies ◽

Ion Bombardment ◽

Physical Parameters ◽

Angle Of Incidence ◽

Ion Sputtering ◽

Scaling Properties ◽

Fractal Surfaces ◽

Experimental Parameters

ABSTRACTRecently a number of experimental studies focusing on the scaling properties of surfaces eroded by ion bombardment provided apparently contradictory results. A number of experiments report the observation of self-affine fractal surfaces, while others provide evidence about the development of a non-fractal periodic ripple structure. To explain these discrepancies, here we derive a stochastic nonlinear equation that describes the evolution and scaling properties of surfaces eroded by ion bombardment. The coefficients appearing in the equation can be calculated explicitly in terms of the physical parameters characterizing the sputtering process. We find that transitions may take place between various scaling behaviors when experimental parameters, such as the angle of incidence of the incoming ions or their average penetration depth, are varied.

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Roughening by Ion Bombardment: A Stochastic Continuum Equation

MRS Proceedings ◽

10.1557/proc-367-299 ◽

1994 ◽

Vol 367 ◽

Author(s):

R. Cuerno ◽

A.-L. Barabasi

Keyword(s):

Nonlinear Equation ◽

Penetration Depth ◽

Ion Bombardment ◽

Physical Parameters ◽

Angle Of Incidence ◽

Scaling Properties ◽

Cascade Theory ◽

Linear Cascade ◽

Continuum Equation ◽

Experimental Parameters

AbstractIn the context of linear cascade theory, we derive a stochastic nonlinear equation to describe the evolution and scaling properties of surfaces eroded by ion bombardment. The coefficients appearing in the equation are calculated explicitly in terms of the physical parameters characterizing the sputtering process. We find that transitions may take place between various scaling behaviors when experimental parameters such as the angle of incidence of the incoming ions or their average penetration depth, are varied.

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Analytical and Experimental Simulation of Loose Pedestal Dynamic Effects on a Rotating Machine Vibrational Response

13th Biennial Conference on Mechanical Vibration and Noise: Rotating Machinery and Vehicle Dynamics ◽

10.1115/detc1991-0223 ◽

1991 ◽

Author(s):

Pavel Goldman ◽

Agnes Muszynska

Keyword(s):

Excitation Frequency ◽

Experimental Studies ◽

Experimental Simulation ◽

Physical Parameters ◽

Vibrational Response ◽

Rotating Machine ◽

Qualitative Pattern ◽

The Impact ◽

Good Agreement ◽

Periodic Changes

Abstract This report presents experimental, analytical, and numerical results describing vibrational phenomena in a rotating machine with one loose pedestal. The loose-pedestal machine rotor vibrations represent unbalance-related excited vibrations of synchronous and fractional subsynchronous regimes. In this study the loose-pedestal machine is first simulated by a simple vibrating beam excited by a shaker mounted on it. The shaker simulates an unbalanced machine rotor. The beam occasionally enters in contact with the foundation. The excited vibrations are modified by impacting occurrences, and by periodic changes in system stiffness. A new model of the impact has been developed. The results of analytical and experimental studies stand in a good agreement. They illustrate the existence of the synchronous regime and several subsynchronous fractional regimes in various excitation frequency ranges. The analysis adequately predicts the occurrence of these regimes and determines the physical parameters affecting them. The analytical and experimental results are then compared with the responses of experimental rotor rig with one bearing pedestal looseness. They show the same qualitative pattern.

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Light ion sputtering of fusion reactor materials in dependence of angle of incidence

Journal of Nuclear Materials ◽

10.1016/0022-3115(82)90620-1 ◽

1981 ◽

Vol 103 ◽

pp. 339-343 ◽

Cited By ~ 14

Author(s):

J. Bohdansky ◽

G.L. Chen ◽

W. Eckstein ◽

J. Roth

Keyword(s):

Fusion Reactor ◽

Angle Of Incidence ◽

Ion Sputtering ◽

Reactor Materials

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Inelastic seismic shear amplification due to higher mode effects in reinforced concrete coupled walls

Earthquake Spectra ◽

10.1177/87552930211053347 ◽

2021 ◽

pp. 875529302110533

Author(s):

Gabriel Rivard ◽

Steeve Ambroise ◽

Patrick Paultre

Keyword(s):

Reinforced Concrete ◽

Parametric Study ◽

Numerical Study ◽

Plastic Hinge ◽

Experimental Studies ◽

Physical Parameters ◽

Intensity Level ◽

Shear Forces ◽

Coupled Walls ◽

Seismic Shear

Recent numerical and experimental studies on reinforced concrete shear walls and coupled walls have shown shear forces greater than expected when the walls are subjected to earthquakes at an intensity level that does not exceed the design values. This amplification of shear forces is attributable to the effects of higher modes after the walls develop a plastic hinge at the base. These effects have been recently recognized in North American design codes for cantilever walls and is currently neglected in the design of ductile coupled walls. As part of the research program described in this article, a parametric study was carried out on coupled wall systems to identify the geometric and physical parameters having the greatest influence on the seismic shear amplification. Using the results of this parametric study, an extensive numerical study was conducted on classes of ductile coupled walls subjected to seismic excitation representative of Western and Eastern Canada. This extensive study led to the establishment of shear amplification prediction equations for use in building codes.

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UV-Induced Fractal Surfaces

Fractals ◽

10.1142/s0218348x97000267 ◽

1997 ◽

Vol 05 (02) ◽

pp. 275-280 ◽

Cited By ~ 2

Author(s):

Cs. Beleznai ◽

R. Vajtai ◽

L. Nánai

Keyword(s):

Surface Morphology ◽

Structural Parameters ◽

Strong Dependence ◽

Pulsed Laser ◽

Fractal Dimensions ◽

Laser Source ◽

Physical Parameters ◽

Fractal Surfaces

Poly (tetrafluorethylene) and polyimide samples were irradiated by a pulsed laser source at 308 nm and the resulting surface morphology was investigated. The photoablated surfaces show a strong dependence on the optical and structural parameters of the polymers. The roughness of the fractal surfaces has been characterized by means of calculating their fractal dimensions and the results are interpreted as a function of the polymer physical parameters.

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Grazing Incidence X-ray Fluorescence Analysis with Monochromatic Radiation

Advances in X-ray Analysis ◽

10.1154/s0376030800014348 ◽

1990 ◽

Vol 34 ◽

pp. 71-80 ◽

Cited By ~ 1

Author(s):

Manfred Schuster

Keyword(s):

Penetration Depth ◽

Fluorescence Intensity ◽

Dopant Concentration ◽

Fluorescence Analysis ◽

Analytical Description ◽

Grazing Incidence ◽

Concentration Profiles ◽

Angle Of Incidence ◽

X Ray ◽

Si Wafer

AbstractX-ray fluorescence excited by a monochromatic collimated Mo-Kα beam at grazing incidence is measured as a function of the angle of incidence. Monochromatic excitation guarantees a well-defined penetration depth and enables a simple analytical description of the fluorescence intensity. This method is applied to a system of thin Cu and Ti metallization layers on a Si wafer and to As dopant concentration profiles in Si wafers.Thereby, the effect of annealing can be analyzed non-destructively.

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Noble-gas ion sputtering yield of gold and copper: Dependence on the energy and angle of incidence of the projectiles

Physical Review B ◽

10.1103/physrevb.35.2198 ◽

1987 ◽

Vol 35 (5) ◽

pp. 2198-2204 ◽

Cited By ~ 36

Author(s):

A. Oliva-Florio ◽

R. A. Baragiola ◽

M. M. Jakas ◽

E. V. Alonso ◽

J. Ferrón

Keyword(s):

Noble Gas ◽

Angle Of Incidence ◽

Ion Sputtering ◽

Sputtering Yield

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The Solar Transmittance of Some Convection Suppression Devices for Solar Energy Applications: An Experimental Study

Journal of Solar Energy Engineering ◽

10.1115/1.3266309 ◽

1982 ◽

Vol 104 (3) ◽

pp. 251-256 ◽

Cited By ~ 22

Author(s):

J. G. Symons

Keyword(s):

Experimental Studies ◽

Diffuse Radiation ◽

Azimuth Angle ◽

Test Facility ◽

Integrating Sphere ◽

Angle Of Incidence ◽

Correlation Equations ◽

Energy Applications ◽

Radiation Properties ◽

Extensive Information

The solar transmittance of seven convection suppression devices (CDSs) has been measured as a function of both angle of incidence and azimuth angle using a large integrating sphere test facility. The CSD designs tested include a honeycomb and various slat geometries made from FEP Teflon1 film, and a tubular glass honeycomb. All FEP Teflon CSDs tested had solar transmittances not less than 0.94 for angles of incidence up to 45 deg, whereas for the glass tubular CSD, the solar transmittance was not less than 0.87 over the same range. The results for FEP Teflon CSDs compare well with previous theoretical and experimental studies of similar CSDs. Empirical solar transmittance correlation equations have been derived, based on a simple CSD solar transmittance model, and they match the measured performance of the CSDs to within 2 percent. The transmittance, reflectance, and absorptance of each CSD to isotropic diffuse radiation have been determined. The radiation properties data presented provides extensive information on some alternative CSD designs, some of which have not been analysed previously.

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