Spectroscopic Study of Arc Temperature Profiles of a Switching-off Process in a Model Chamber

A model chamber was applied to emulate a switching-off process which is very similar to those in real high-voltage circuit-breakers. The arc between moved W-Cu electrodes through a PTFE nozzle in SF6 was considered. Transparent windows in the chamber wall and a slit in the nozzle enabled an optical in-vestigation of the arc cross section several milliseconds before current zero. The side-on radiance of fluo-rine atom lines has been measured. Considering rotational symmetry of the arc the corresponding radial emission coefficients have been determined. Radial temperature profiles have been obtained with uncer-tainties below 10% considering change of window transmission and optical depth of the line radiation. The experimentally determined temperature profiles are used to validate a CFD simulation of the switch-ing-off process in the model chamber