Analysis of C2 Swan Bands in Ablation-Dominated Arcs in CO2 Atmosphere

Abstract

A model circuit breaker in a high-pressure chamber filled with CO<sub>2</sub> 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 C<sub>2</sub> 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 C<sub>2</sub> in the active phase and the formation of CuF near to current zero.

Comparison of measurement and numerical calculation on spectral profile of ablation arc plasma around current zero in high-voltage gas circuit breakers

“…Optical measurement techniques have been used widely to investigate arc phenomena such as particle composition [9,10], temperature [11][12][13][14][15], and electron density [16]. The authors have used optical emission spectroscopy (OES) to investigate ablation gas behaviour in a product-scale interrupter with an interrupting current of 20 kA in root mean square (rms) value [17].…”

“…In two earlier studies [17,18], the absorption spectra of C 2 molecules were measured during the large current phase. Another study [10] used spectroscopy for the arc cross-section. The C 2 Swan bands were observed as absorption close to the nozzle wall.…”