The dynamic-electrostatic probe in low temperature high pressure plasma stream

One of the plasma diagnostics, probe method can make local measurement and be done by extremely simple device. As the probe is immersed in the low temperature high pressure plasma stream, it becomes so hot that it could emit electrons or vaporize, further more overheating of it could cause sputtering of its material. The measurements were carried out using a moving electrostatic probe, which crossed the jet in the radial direction at the speed of 1.4 m/sec. A number of measurements were made along the center line of the jet. Experiments were made at arc current of 100 A, Argon gas flow rate 4 l/min. The electron temperature at the center of the jet and 2 mm from the nozzle exit was 14,900 K, and was in agree with that by the spectroscopic method. The electron temperature for radial survey dropped more quickly than that for axial survey. The electron density at the center of the jet and 2 mm from the nozzle exit was 8.2 x 1019 m-3, and that for radial survey decrease more quickly than that for axial survey. The electron density was fewer than that of Grey's experiment by approximately 3 order. (author)