A good understanding of the pressure distribution within
a vacuum system is essential to the economical selection and
placement of pumps and chambers. As the complexity of the
vacuum system increases, so does the complexity of the
calculations required to characterize the pressure distribution.
For this reason a number of finite element programs have
been developed to analyze the pressure in vacuum systems. In
many cases existing commercial finite element programs can
be used to analyze pressure distributions. When they are
applicable, commercial finite element programs have the
advantages of wide distribution and well developed user
interfaces.
A commercial finite element program may be used for vacuum
analysis in the high vacuum region. In the free-molecular-flow
region an analogy can be made between gas flow and linear
thermal conduction. One technique for implementing the
analogy is described in this paper. It will be illustrated with an
example for a simple vacuum system.
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