Abstract
Test results are presented for different configurations of newly developed optical sensors consisting of several narrow-collimated photo detectors pointed at a plasma jet along different directions in its cross section. The sensors are capable of detecting time-variations of the position, width and asymmetry of a plasma jet. Two plasma torches with different plasma forming gas, air and argon/water vapor mixture, were used in our experiments under typical atmospheric plasma spraying (APS) conditions. The tests are based on fast, side-on imaging of the plasma jet from two or three angles (viewpoints). Reference values for the jet center coordinates, width and maximum brightness were deduced by processing the full information in the images. Next, data from small areas were processed to obtain values of the same parameters that simulate the sensor actual performance. It is commented that the accuracy of the new sensors seems reasonable for the purpose of on-line control of APS.
