High‐speed spectroscopic measuring apparatus for contact arc discharges using CCD image sensor

Numerous studies have been made on contact arc discharges. However, little has been reported on the detailed measurement of discharge phenomena. With a view to obtaining basic data to be used for the improvement of contact performance, an apparatus has been developed which performs parallel spectroscopic measurement of spectral arc intensities. The arc passing through the spectroscopic analyzer is focused on a CCD image sensor by means of a lens. Each spectral line is correlated to CCD picture elements. CCD has 128 pixels and the apparatus can measure arc spectral lines at 350 ∼ 700 nm in parallel and with a 1 ms interval. The arc voltage and current forms can also be measured. All the data undergo an A/D conversion and are stored on a floppy disk. Hence, the arc discharge can be studied quantitatively and the fine structures in the arc may be analyzed. From the present experiment it is found that the arc is maintained with a larger variety of ambient atoms in the Pb contact arc than in Ag. A transition from the metallic phase to the gaseous phase has been confirmed for the Ag contact arc.