Measurement and modeling of Ar ∕ H 2 ∕ C H 4 arc jet discharge chemical vapor deposition reactors. I. Intercomparison of derived spatial variations of H atom, C 2 , and CH radical densities
Comparisons are drawn between spatially resolved absorption spectroscopy data obtained for a 6.4 kW dc arc jet reactor, operating with Ar ∕ H 2 ∕ C H 4 gas mixtures, used for deposition of thin, polycrystalline diamond films, and the results of a two-dimensional ( r , z ) computer model incorporatin...
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| Published in | Journal of applied physics Vol. 102; no. 6; pp. 063309 - 063309-13 |
|---|---|
| Main Authors | , , , , , , |
| Format | Journal Article |
| Published |
American Institute of Physics
28.09.2007
|
| Online Access | Get full text |
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| Summary: | Comparisons are drawn between spatially resolved absorption spectroscopy data obtained for a
6.4
kW
dc arc jet reactor, operating with
Ar
∕
H
2
∕
C
H
4
gas mixtures, used for deposition of thin, polycrystalline diamond films, and the results of a two-dimensional
(
r
,
z
)
computer model incorporating gas activation, expansion into the low pressure reactor, and the chemistry of the neutral and charged species. The experimental measurements, using either cavity ring-down spectroscopy or diode laser absorption spectroscopy, determined absolute number densities of
H
(
n
=
2
)
atoms, and column densities of
C
2
(
a
Π
u
3
)
,
C
2
(
X
Σ
g
+
1
)
, and
C
H
(
X
Π
2
)
radicals, with vibrational and rotational quantum state resolutions, and their variation with height through the horizontally propagating arc jet plume. Spectra were also analyzed to obtain temperatures and local electron densities [from Stark broadening of
H
(
n
=
2
)
absorption lines]. The experimental data are directly compared with the output data of the model that returns spatially inhomogeneous temperature, flow velocities, and number densities of 25 neutral and 14 charged species. Under the base operating conditions of the reactor [
11.4
SLM
(standard liters per minute) of Ar and
1.8
SLM
of
H
2
entering the primary torch, with addition of
80
SCCM
(SCCM denotes cubic centimeter per minute at STP) of
C
H
4
downstream;
6.4
kW
input power; reactor pressure of
50
Torr
], the calculated and measured column and number densities agree to within factors of 2-3, the model reproduces the spatial dependence of column densities, and the mean temperatures of
C
2
(
a
)
and
C
H
(
X
)
radicals derived from spectra and model results are in good agreement. The model also captures the variation of these parameters with changes to operating conditions of the reactor such as flows of
H
2
and
C
H
4
, and input power. Further details of the model and the insights it provides are the subject of the accompanying paper [
Mankelevich
,
J. Appl. Phys.
102
,
063310
(
2007
)
]. |
|---|---|
| ISSN: | 0021-8979 1089-7550 |
| DOI: | 10.1063/1.2783890 |