Validation of projected length of the rotating gliding arc plasma using 'regionprops' function

This work investigates the reliability of the function called 'regionprops' which is used for measuring the 2D length of the plasma discharge. Work was conducted in a Rotating Gliding Arc (RGA) reactor, using air as plasma forming gas. Arc rotational images at three different gas flow rates i.e. 5, 25 and 50 litres per minute (LPM) were captured using high speed camera with an exposure of 100 μs. A total of 6799 images from all the three flow rates were considered for analysis. The 2D length of the discharge was measured by two methods namely, (a) 'regionprops' function (Python) and (b) manual tracing (ImageJ). The 2D arclength measured using 'regionprops' function matched very closely to that measured by manual hand tracing technique using ImageJ tool. A linear relation between both the methods was observed for all the three flow rates, with the coefficient of determination i.e. R2 > 0.9. The validation of 'regionprops' function shown in this work marks an important step as the function is simple to use and adapt compared to any other techniques such as shortest-path algorithm. © 2020 IOP Publishing Ltd