Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Continuum and Kinetic Simulations of the Neutral Gas Flow in an
  Industrial Physical Vapor Deposition Reactor   Magnetron sputtering used for physical vapor deposition processes often
requires gas pressures well below 1 Pa. Under these conditions the gas flow in
the reactor is usually determined by a Knudsen number of about one, i.e., a
transition regime between the hydrodynamic and the rarefied gas regime. In the
first, the gas flow is well described by the Navier-Stokes equations, while in
the second a kinetic approach via the Boltzmann equation is necessary. In this
paper the neutral gas flow of argon and molecular nitrogen gas inside an
industrial scale plasma reactor was simulated using both a fluid model and a
fully kinetic Direct Simulation Monte Carlo model. By comparing both model
results the validity of the fluid model was checked. Although in both models a
Maxwell-Boltzmann energy distribution of the neutral particles is the natural
outcome, the results of the gas flow differ significantly. The fluid model
description breaks down, due to the inappropriate assumption of a fluid
continuum. This is due to exclusion of non-local effects in the multi
dimensional velocity space, as well as invalid gas/wall interactions. Only the
kinetic model is able to provide an accurate physical description of the gas
flow in the transition regime. Our analysis is completed with a brief
investigation of different definitions of the local Knudsen number. We conclude
that the most decisive parameter - the spatial length scale L - has to be very
careful chosen in order to obtain a reasonable estimate of the gas flow regime.

23
The categories of this paper are: solv-int
37
The categories of this paper are: supr-con
12
The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc
8
The categories of this paper are: hep-ex
33
The categories of this paper are: plasm-ph
28
The categories of this paper are: alg-geom
22
The categories of this paper are: chao-dyn
0
The categories of this paper are: hep-ph
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
18
The categories of this paper are: econ
16
The categories of this paper are: stat
27
The categories of this paper are: comp-gas
29
The categories of this paper are: funct-an
15
The categories of this paper are: nucl-ex