Analysis of C2 SWAN bands in ablation-dominated arcs in CO2 atmosphere

Abstract

A model circuit breaker in a high-pressure chamber filled with CO2 atmosphere is used to operate a wall-stabilized arc of several kilo-amperes between tungsten-copper electrodes surrounded by polytetrafluoroethylene nozzles. Optical emission spectroscopy (OES) is carried out via quartz plates inserted into the nozzles using a combination of an imaging spectrometer either with a high-speed video camera or with an ICCD camera. Depending on the nozzle geometry and the current, continuum from C2 Swan bands was detected as absorption as well as emission pattern. After current zero, optical absorption spectroscopy (OAS) using a xenon flashlamp as broadband background radiator was applied. An absorption around 493 nm was detected and attributed to CuF molecules. The study proofs the existence of C2 in the active phase and the formation of CuF near to current zero.