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

摘要

A method for estimating metallic vapour concentration in a post-are channel on the basis of a spectroscopic method was proposed. Using the method, the axial distribution of metallic vapour concentration in a post-are channel was measured around the nozzle throat in a flat-type SF6 gas-blast quenching chamber. In the chamber iron was intentionally used as an electrode material since Fe spectral lines at wavelengths of 426.0 and 442.7 nm have very much higher radiation intensities than particles such as S+, F or Cu at temperatures below 6000 K. The proposed 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 that X(Fe) has a magnitude around 1 x 10(-2)% along the nozzle axis during the period from -60 to 100 Cts after current zero for 5 kA arcs. [References: 46]