scholarly journals Топография поверхности и пропускание света кварцевыми окнами после экспозиции в высокочастотном разряде в дейтерии и смеси дейтерия с азотом

2021 ◽  
Vol 91 (2) ◽  
pp. 299
Author(s):  
А.Е. Городецкий ◽  
А.В. Маркин ◽  
В.Л. Буховец ◽  
В.И. Золотаревский ◽  
Р.Х. Залавутдинов ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Discharge Plasma ◽  
Scattered Light ◽  
Spectral Density Function ◽  
Surface Layers ◽  
Plasma Exposure ◽  
Rf Discharges ◽  
Near Ir ◽  
Power Spectral ◽  
Roughness Analysis

The effect of a cleaning discharge plasma on the KU-1 optical quartz surface topography and transmission in visible and near IR ranges (400-1000 nm) was studied. For the study, we used crossed DC and RF discharges in D2 and D2/N2 mixture, where the N2 fraction was ~25 mol %. The addition of nitrogen increased sputtering rate from 250 to 1200 nm / h while maintaining stoichiometry of the surface layers. The rms surface roughness decreased after the plasma exposure from 1.3 to 0.6 nm, while the quartz transmittance has not changed. The surface roughness analysis and calculation of diffusion scattered light at 400 nm transmitted through the quartz were performed using the power spectral density function of AFM.

Roughness Analysis of Episurfaces Grown on Ion-Beam Processed GaSb Substrates

2004 ◽  
Vol 829 ◽  
Author(s):  
K. Krishnaswami ◽  
D. B. Fenner ◽  
S. R. Vangala ◽  
C. Santeufemio ◽  
M. Grzesik ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Statistical Analysis ◽  
Ion Beam ◽  
Molecular Beam Epitaxial ◽  
Power Spectral ◽  
Sharp Point ◽  
Roughness Analysis ◽  
Cluster Ion ◽  
Gas Cluster Ion Beam ◽  
Substrate Surfaces

ABSTRACTHigh-quality GaSb substrates with minimal surface roughness and thin, uniform oxide layers are critical for developing low-power, epitaxy-based, electronic and optoelectronic devices. Ion-beam processing techniques of gas-cluster ion beam (GCIB) and bromine ion-beam assisted etching (Br-IBAE) were investigated as to their potential for improving the suitability of substrate surfaces for molecular beam epitaxial (MBE) growth. Statistical analysis of the residual surface roughness provides insight into ion-beam processing and its impact on epitaxial growth. Images of episurfaces grown on chemical mechanical polished (CMP), Br-IBAE, and GCIB finished substrates were obtained using atomic force microscopy (AFM) and these were statistically analyzed to characterize their surface roughness properties. Autocorrelation analysis of the first two types of episurfaces showed a quick loss of correlation within ∼100 nm. The episurface with Br-IBAE also showed isotropic mound roughness with sharp point-like protrusions. The GCIB prepared episurfaces exhibited the formation of uniform step-terrace patterns with monatomic steps and wide terraces as indicated by the strong, long range (>0.5 μm) correlations. Statistical analysis of the GCIB episurfaces showed self-similar random fractal behavior over eight orders of magnitude in the power spectral density (PSD) with a fractal dimension of ∼2.5.

Prediction of Atmospheric Turbulence Characteristics for Surface Boundary Layer using Empirical Spectral Methods

2020 ◽  
Author(s):  
Yagya Dutta Dwivedi ◽  
Vasishta Bhargava Nukala ◽  
Satya Prasad Maddula ◽  
Kiran Nair
Keyword(s):  
Boundary Layer ◽  
Time Series ◽  
Surface Roughness ◽  
Wind Speed ◽  
Atmospheric Turbulence ◽  
Surface Boundary ◽  
Low Frequencies ◽  
Surface Boundary Layer ◽  
Power Spectral ◽  
Mean Wind Speed

Abstract Atmospheric turbulence is an unsteady phenomenon found in nature and plays significance role in predicting natural events and life prediction of structures. In this work, turbulence in surface boundary layer has been studied through empirical methods. Computer simulation of Von Karman, Kaimal methods were evaluated for different surface roughness and for low (1%), medium (10%) and high (50%) turbulence intensities. Instantaneous values of one minute time series for longitudinal turbulent wind at mean wind speed of 12 m/s using both spectra showed strong correlation in validation trends. Influence of integral length scales on turbulence kinetic energy production at different heights is illustrated. Time series for mean wind speed of 12 m/s with surface roughness value of 0.05 m have shown that variance for longitudinal, lateral and vertical velocity components were different and found to be anisotropic. Wind speed power spectral density from Davenport and Simiu profiles have also been calculated at surface roughness of 0.05 m and compared with k−1 and k−3 slopes for Kolmogorov k−5/3 law in inertial sub-range and k−7 in viscous dissipation range. At high frequencies, logarithmic slope of Kolmogorov −5/3rd law agreed well with Davenport, Harris, Simiu and Solari spectra than at low frequencies.

Experimental Observation of Fractal-Regular Surfaces and a Transformation Scheme for Extracting Fractal Parameters

2005 ◽  
Author(s):  
Shao Wang ◽  
Wai Kin Chan
Keyword(s):  
Silicon Wafer ◽  
Roughness Parameter ◽  
Hard Disk ◽  
Spectral Density Function ◽  
Power Spectral ◽  
Fractal Parameters ◽  
Asperity Contacts ◽  
Fractal Roughness ◽  
Magnetic Hard Disk ◽  
Wafer Surfaces

To account for the effects of asperity contacts at various length scales, it is appropriate to characterize an engineering surface as a fractal-regular surface. In spite of significant theoretical advancement, there is a desperate need for experimental verification of the theory of fractal-regular surfaces and a consistent scheme of obtaining the fractal parameters. In the present study, the existence of a fractal region and a regular-shape region in the power spectral density function for fractal-regular surfaces was confirmed experimentally, for the first time, with data obtained from magnetic hard disk and silicon wafer surfaces. A novel scheme involving a variable transformation was developed to extract fractal parameters. This scheme was validated by accurate recovery of fractal parameters from simulated surfaces. The fractal dimension, the fractal roughness parameter and the fractal domain length were found for magnetic hard disk and silicon wafer surfaces.

The Modification of Carbon Included Polyethylene Surface by Plasma Treatment for Metallizing Using a Low Pressure RF Discharge Plasma

2005 ◽  
Vol 8 (1) ◽  
Author(s):  
Jeou-Long Lee ◽  
Chung-Ming Liu ◽  
Kuen Ting ◽  
Wei-Kung Cheng ◽  
Takayoshi Tsuchida ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Surface Layer ◽  
Discharge Plasma ◽  
Treatment Time ◽  
Low Pressure ◽  
Rf Discharge ◽  
Nickel Layer ◽  
Good Adhesion ◽  
Polyethylene Surface

AbstractSurface modification of the carbon included polyethylene (semi-conductive PE) surface for metallizing using a low pressure RF discharge plasma has been carried out. The contact angle was used as a measure of the wettability of the PE surface. The roughness and the chemical bondings in PE surface layer were analized by DFM and XPS, respectively. Typical results show that the contact angle decreases from approximately 94° to below 10° after several minutes' treatment and recovers to a saturation value when it was put open to the air after treatment. The saturation value of the contact angle is smaller as the gas pressure for treatment is higher and the treatment time is longer but all are below approximately 60° which is still smaller than that of untreated. DFM and XPS results show that the surface roughness and the bondings C-O and C=O in the PE surface layer also increase with increasing the treatment time and seem to be responsible for improving the hydrophilic property of PE. After pretreatment process, nickel was coated on the PE sheet by electrodeposition method and a good adhesion between the nickel layer and the PE surface compared with that of untreated was obtained.

Surface properties of composite resins with and without fluorides for bracket bonding / Propriedades de superfície de resinas compostas com e sem fluoretos para colagem de suportes

2021 ◽  
Vol 7 (7) ◽  
pp. 67267-67276
Author(s):  
Emillyn Jones Greijal Dias Holanda ◽  
José Guilherme Neves ◽  
Milton Santamaria-Jr ◽  
Silvia Amélia Scudeler Vedovello ◽  
Ana Rosa Costa ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Surface Properties ◽  
Color Change ◽  
Composite Resins ◽  
Hardness Tester ◽  
Significant Difference ◽  
Post Test ◽  
Roughness Analysis ◽  
Diamond Paste ◽  
Penetration Time

The aim of this study was to evaluate the surface properties of orthodontic resins with and without fluoride. Forty disks, measuring 2 mm thick by 6 mm in diameter, were made of 4 bracket-bonding composite resins (n=10): Transbond Plus Color Change-3M/Unitek (TPCC); Transbond XT- 3M/Unitek (TXT), Orthocem -FGM (OC); Orthocem UV Trace-FGM (OCUV). The discs were photoactivated for 40 seconds with irradiance of 450 mW/cm2 and manually polished in sequence by silicon carbide sandpapers with 1200 and 2000 grain size and finished with diamond paste and felt disc. The surface microhardness analysis was performed using a Shimadzu Micro Hardness Tester HMV-2,000 (Shimadzu Corporation, Kyoto, Japan) with a load of 50 gF and a 5 second penetration time. Surface roughness readings were taken using a Surf Corder Roughness Meter (SE 1700- Kosaka, Lisboa-Portugal). For data analysis, ANOVA (one-way) was used, followed by Tukey's post-test (?=0.05). The microhardness results showed a difference (p?0.05) in the means of the orthodontic resins between TPCC and TXT with the other groups. After the surface roughness analysis, the averages showed that TPCC resin showed higher roughness compared to OC and OCUV (p?0.05), and there was no statistical difference with TXT. It was concluded that statistically the composite resins with fluoride showed significant difference regarding hardness and roughness.

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