Chemistry Reference
In-Depth Information
5
e + CF
4
4
To t a l
3
CF
3
+
CF
2
+
×10
2
CF
+
×10
F
+
×10
1
C
+
CF
2
++
×10
CF
3
++
×10
0
0
20
40
60
80
100
120
140
160
180
200
Electron energy in eV
FIGURE 3.22
Partial and total electron impact ionization cross section of CF
4
. (Data from
Stephan, K. et al.,
J. Chem. Phys.
, 83, 5712, 1985.)
The combination of the equations (3.115) and (3.116) results in (3.117)
m
red
2
·
m
red
2
·
π
·
b
2
σ
σ
eff
+
ε
=
v
2
φ
+
ε
thres
=
v
th
·
b
eff
+
ε
thres
=
ε
·
ε
thres
(3.117)
π
·
and provides the cross section for ε
>
ε
thres
:
1
.
ε
thres
ε
σ
=
σ
eff
·
−
(3.118)
3.4 PLASMA KINETICS
3.4.1 T
HE
B
OLTZMANN
E
QUATION
Besides the microphysics of elementary collision processes the collective behavior
of the plasma particles needs a statistical treatment to determine their movement in
the six-dimensional phase space
, the production and recombination of charged
particles as well as the chemical reactions under nonequilibrium conditions. Here,
the knowledge of the single particle velocity distribution function of the different
plasma particles (electrons, ions, neutrals) is of fundamental interest to describe the
nonthermal plasma as many-particle system. In particular, the knowledge of velocity
distribution functions is a precondition for
(
r
,
v
)
1. The calculation of the weighted average of local physical quantities which
can be directly compared with experimental data
2. The fluid modeling of nonthermal plasmas using conservation quantities
and macroscopic transport equations
