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Growth rate studies of CVD diamond in an RF plasma torch (1994)

Baldwin, S. K. ; Owano, T. G. ; Kruger, C. H.

Springer

Plasma chemistry and plasma processing 14 (1994), S. 383-406

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ISSN: 1572-8986

Keywords: Chemical vapor deposition ; diamond synthesis ; growth rate studies ; atmospheric pressure ; inductively coupled plasma ; optical emission spectroscopy

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology

Notes: Abstract This paper addresses the complex chemistry in the boundary later over a substrate in a chemical vapor deposition rector at atmospheric pressure. In this study, a highspeed plasma (140m/s) was created using a radio-frequency inductively coupled plasma torch for the deposition of diamond thin films. Growth rates on the order of 50 μm/ h were obtained for well-faceted continuous films grown on molybdenum substrates positioned normal to the plasma flow. The highest growth rates were obtained at substrate temperatures of 1370 K and a feed gas ratio of 2.5% CH4 in H2. Growth rates are compared to predicted results obtained from numerical simulations, based on a one-dimensional stagnation-point flow, and are/mend to be in good agreement. Several other surface analysis techniques were used to characterize the deposited films, inchaling SEA/, Raman spectroscopy, transmission electron microscopy. Rutherfard backscattering spectroscopy, and hydrogen-forward recoil spectroscopy. Optical emission spectroscopy was used to characterize the RF plasma during the deposition process. Results from these studies form an important database for the validation and improvement of current models of the atmospheric-pressure diamond CVD environment.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01570203

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The development of a structured mesh grid adaption technique for resolving shock discontinuities in upwind Navier-Stokes codes (1995)

Patel, M. K. ; Pericleous, K. A. ; Baldwin, S.

Chichester : Wiley-Blackwell

International Journal for Numerical Methods in Fluids 20 (1995), S. 1179-1197

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ISSN: 0271-2091

Keywords: adaptive grids ; equidistribution ; compressible viscous aerodynamics ; CFD modelling ; Engineering ; Engineering General

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Notes: A technique is described for the adaptation of a structured control volume mesh during the iterative solution process of the Navier-Stokes equations. The scalar equidistribution method is adopted, in conjunction with a Laplace-like grid solver to make a curvilinear body-fitted grid sensitive to local flow gradients. Hence, whilst the total number of grid nodes remains constant during a computation, their relative position is continuously adjusted to promote clustering of cells in regions where gradients are high. The focus of this work is in compressible aerodynamics, where such clustering would be desirable in regions containing shocks but also in boundary layers. The technique is three-dimensional and operates in a series of user-defined grid subdomains or patches. These patches act as reference frames within which grid activity takes place. Bi-cubic splines are extensively used to define the aerodynamic surfaces forming the calculation boundaries and to ensure that grid movement does not compromise surface integrity. The technique is applied to aerofoils, wing surfaces, transonic ducts and nozzles and a supersonic wedge cascade. Significant sharpening of both normal and oblique shock discontinuities is demonstrated over static grid simulations and with fewer overall grid nodes. The technique is successful in both inviscid and viscous (turbulent) simulations.

Additional Material: 16 Ill.