Geoscience Reference
In-Depth Information
Fig. 6.12
Pressure sensor signals in different duct ports. Capacity-coupled high-frequency dis-
charge in vortex airflow.
V
t
40 Torr. Minimal high-frequency
plasma generator operation time is marked by
magenta lines
. A distance of a section from the
high-frequency electrode, at which a measuring port was located, is in cm
140 m/s,
P
HF
D
1.7 kW,
P
st
D
used to measure gas temperature inside the plasma formation. We observed many
erosive tungsten clusters created by the capacity-coupled high-frequency discharge
(caused by tungsten electrode erosion). These particles help us to measure the gas
temperature in the plasma by the pyrometer. The optical spectrometer AvaSpec 2048
(with wavelength resolution ı
0.2 nm) is used to measure the gas temperature
inside the plasmoid (Klimov
2009
).
The experimental conditions were the following:
High frequency
F
HF
D 13.6 MHz
Electric power
P
d
D
1.9 kW
P
st
10
5
Static pressure in airflow
Pa
Airflow velocity (axial)
V
ax
30 m/s
Tangential airflow velocity
V
t
30 m/s
The following parameters were measured in this experiment:
Q
af
,themass
airflow rate in the quartz tube; ı
T
, the average airflow temperature increase,
measured by the thermocouples near the tube axis (
X
), and near the tube wall
(
W
) at the high-frequency discharge plasma-on;
T
w
, wall temperature;
T
el
, electrode
temperature; the chemical composition of the gas flow; and
M
el
, the erosion mass of
the electrode material.