TRANSIENT DISTRIBUTION OF METALLIC VAPOR CONCENTRATION IN A POST-ARC CHANNEL AFTER CURRENT ZERO ALONG THE NOZZLE AXIS IN A FLAT-TYPE SF6 GAS-BLAST QUENCHING CHAMBER

A method for estimating metallic vapour concentration in a post-are ch annel on the basis of a spectroscopic method was proposed. Using the m ethod, the axial distribution of metallic vapour concentration in a po st-are channel was measured around the nozzle throat in a flat-type SF 6 gas-blast quenching chamber. In the chamber iron was intentionally u sed as an electrode material since Fe spectral lines at wavelengths of 426.0 and 442.7 nm have very much higher radiation intensities than p articles such as S+, F or Cu at temperatures below 6000 K. The propose d method was capable of determining the iron vapour concentration X(Fe ) up to 100 mu s after current zero in the experiment. It was found th at X(Fe) has a magnitude around 1 x 10(-2)% along the nozzle axis duri ng the period from -60 to 100 Cts after current zero for 5 kA arcs.