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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.
 
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