Spectroscopic determination of temperatures in plasmas generated by arc torches

Abstract Two different arc plasma torches and especially their plasma jets are studied using optical emission spectra. Results include temperatures obtained from emission lines of atoms, ions and diatomic molecules in various distances along the axes of the plasma jets. Understanding of temperature distributions is complicated mainly in the downstream turbulent regions of the jets. Several common features are found during comparison of emission spectra and corresponding temperatures. It is shown that Boltzmann plot of rotational lines of OH can serve as a good thermometer in the downstream regions of both jets. It seems that even high temperatures exceeding 6000 K may be measured efficiently by this method.