Chemistry Reference
In-Depth Information
Gas supply
Electrode
systems
Inlet
exhauster
Outlet
exhauster
Foil
+
+
Metal roll
covered with
dieletric
Storage coil
Storage coil
FIGURE 8.27
Scheme of plasma treatment of foils by DBD. (From Meiner, S. et al.,
Surf.
Coat. Technol.
, 98(1-3), 1121, 1998.)
The substrate of width
s
[m] moves across the electrodes of the same width with
the velocity
v
[m/s];
P
[W] is the power introduced into the discharge. The power
density
L
in discharge volume is
W
m
3
,
P
L
=
E
∗
j
=
(8.56)
A
∗
a
where
E
[V/m] is the averaged voltage gradient inside the plasma
j
[A/m
2
] is the current density
A
[m
2
] is the electrode surface
a
[m] is the gap width of the discharge
The power density
O
on the electrode surface is defined by
W
m
2
.
P
A
O
=
(8.57)
The product of
O
and the treatment time gives the dosage for a resting substrate.
The application of atmospheric pressure DBDs for plasma surface treatment is
restricted to thin and flat substrates. Another type of nonthermal plasma sources are
atmospheric pressure plasma jets (see Section 3.8), which are successfully applied
for the treatment of large three-dimensional substrates [157].
The application of low-pressure discharges requires expensive vacuum technique.
Surface treatment in such plasmas is characterized by the action of energetic ions
