Plasma processing dynamics

David B. Graves and Cameron F. Abrams, Molecular Dynamics Simulations if Ion-Surface Interactions with Applications to Plasma Processing Christian M. Lastoskie and Keith E. Gubbins, Characterization of Porous Materials Using Molecular Theory and Simulation... 

With the advent of vector processors over the last ten years, the vector computer has become the most efficient and in some instances the only affordable way to solve certain computational problems. One such computer, the Texas Instruments Advanced Scientific Computer (ASC), has been used extensively at the Naval Research Laboratory to model atmospheric and combustion processes, dynamics of laser implosions, and other plasma physics problems. Furthermore, vectorization is achieved in these programs using standard Fortran. This paper will describe some of the hardware and software differences which distinguish the ASC from the more conventional scalar computer and review some of the fundamental principles behind vector program design. 

MOLECULAR DYNAMICS SIMULATIONS OF ION-SURFACE INTERACTIONS WITH APPLICATIONS TO PLASMA PROCESSING... 

Reactive plasmas are generally characterized as plasmas in which component polyatomic molecules have an important role. Information and ideas, as well as experimental techniques in physical chemistry, particularly in reaction dynamics and kinetics studies, are greatly needed to control the essential features of atomic and molecular processes in reactive plasmas and thus to obtain desired products of reactive-plasma processing such as chemical-vapor deposition (CVD) and etching (Hatano, 1991). 

The fixed nuclear approximation is extremely useful, not only for the bound states, but also for the treatment of electronic scattering by molecules. For instance, stationary-state scattering theories within the fixed nuclear approximation have been extensively developed for molecular photoionization [18, 250, 336, 516] and electron scattering from polyatomic molecules [210, 418, 419]. These scattering phenomena are quite important in that they are widely foimd in nature as elementary processes and even in industrial applications using plasma processes. These scatterings may be referred to as stationary-state electron dynamics in fixed nuclei approximation. 

Waldie, B. The Chemical Engineer (London) No. 261 (1972) 188. Review of recent work on the processing of powders in high temperature plasmas Pt. II. Particle dynamics, heat transfer and mass transfer. 

Chemical vapor deposition is a synthesis process in which the chemical constituents react in the vapor phase near or on a heated substrate to form a solid deposit. The CVD technology combines several scientific and engineering disciplines including thermodynamics, plasma physics, kinetics, fluid dynamics, and of course chemistry. In this chapter, the fundamental aspects of these disciplines and their relationship will be examined as they relate to CVD. 

In a Japanese plasma wind tunnel, SPA specimens were tested up to 3.8 MW/m2 at 0.7 bar aerodynamic pressure (Fig. 12). After a test duration of 60 s, no obvious damage was visible. The surface temperature of about 2600°C was reduced to 100°C within 20 min. Further analysis showed a maximum charred depth of the ablator of 15 mm. The carbonization process did not change the geometric dimensions, the new heat protection system can be considered absolutely stable to deformation. The carbonized layer still has a noticeable pressure resistance and transfers the load applied by the dynamic pressure to the structure. 

Brenner et al. [ 169] applied inductively coupled plasma atomic emission spectrometry to the determination of calcium (and sulfate) in brines. The principal advantage of the technique was that it avoided tedious matrix matching of calibration standards when sulfate was determined indirectly by flame techniques. It also avoided time-consuming sample handling when the samples were processed by the gravimetric method. The detection limit was 70 ig/l and a linear dynamic range of 1 g/1 was obtained for sulfate. 

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