Electron temperature measurement in a premixed flat flame using the double probe method

Abstract

The electron temperatures Te were measured using a double probe in a premixed methane flame produced by a calibration burner according to Hartung et al. The experiment was performed at atmospheric pressure. In contrast to other authors, we have managed to find typical nonlinearities corresponding to the retarding electron current region and to calculate electron temperatures using a suitable fit on the basis of the measured characteristics. A Pt-Rh thermocouple was used to measure temperatures Th corresponding to “heavy” species. Our results indicate that the flame plasma can be considered to be weakly non-isothermic — Te = (2400–4000) K, Th = (1400–1600) K. On the basis of measurement of the saturated ion current, the number density of the charged particles was estimated at (0.3–3.8) · 1017 m-3. The trends in Te and Th in dependence on the positions of the probes and thermocouple in the flame differ substantially; this fact has not yet been explained.