Evaporation and low-pressure vapor phase transport play an important role in
many processes, such as physical vapor deposition and hearth melting of metals.
Opennovation has modeling expertise which can assist in the
design and optimization of such processes, focused around vapor transport and
Vapor Transport in Physical Vapor Deposition
Thin film processes such as electron beam evaporation, sputtering, and pulsed
laser deposition operate at a gas pressure where the mean free path of
molecules between collisions is smaller than the chamber but too large to
consider the gas a continuum. In this pressure range, a methodology called
Direct Simulation Monte Carlo provides an efficient and accurate predictive
model for gas flow and transport. In particular, modeling can calculate the
extent of vapor plume focusing, which determines the thickness profile of
- A. Powell, P. Minson, G. Trapaga and U. Pal,
Modeling of Vapor Plume Focusing in Electron Beam Evaporation,"
Metall. Mater. Trans. 32A:1959-1966 (2001).
- P. Minson, A. Powell and G. Trapaga, "Theory of Vapor Plume Focusing in
Electron Beam Evaporation by the Direct Simulation Monte-Carlo Method,"
Proc. Conf. EBM&R State of the Art 1996, 126-137.
In processes involving liquids with multiple volatile compounds or elements,
each component evaporates at a different rate. The strongly nonlinear
temperature dependence of evaporation rate complicates this when the heat
source is non-uniform or time-dependent, such as in electron beam processing of
metals. Evaporation thus results in a composition change in the liquid which
is often not evenly distributed, and can lead to quality issues in the product.
Specialized codes modeling heat transfer through the surface can efficiently
calculate the time-average evaporation rates of each component, and couple them
with larger-scale codes for heat and mass transfer.
- A. Powell, J. Van Den Avyle, B. Damkroger, J. Szekely and U. Pal,
of Multicomponent Evaporation in Electron Beam Melting and Refining of
Titanium," Metall. Mater. Trans. 38B:1227-1239 (1997).
- A. Powell, J. Van Den Avyle and U. Pal, "Optimal Beam Pattern to Maximize
Inclusion Residence Time in an Electron Beam Melting Hearth," Proc. AVS
Vac. Metall. Conf. 78-84 (1997).
- A. Powell, J. Van Den Avyle, B. Damkroger and U. Pal, "Prospects for
Titanium Alloy Composition Control by Electron Beam Scan Frequency
Manipulation," Proc. Conf. EBM&R State of the Art 1996, 138-150.
- M. Miszkiel, R. Davis, J. Van Den Avyle and A. Powell, "Video Imaging and
Thermal Mapping of the Molten Hearth in an Electron Beam Melting Furnace,"
Proc. Conf. EBM&R State of the Art 1995, 243-254.
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