Two-jet arc plasmotron powder analysis

There has recently been considerable interest in arc and high-frequency plasmotrons for exciting spectra. We give characteristics for such equipment and discuss the prospects for using it in multi-element powder analysis for rocks, ores, and minerals. We examined the axial distributions for the various atomic and ionic lines in relation to the flow rates for the plasma-forming and transport gases. Visual observations showed that the plasma flow expanded as the flow rates decreased and became less dense, with the merging region extending and deviating somewhat from the end of the nozzles. The mixtures were made from spectrally pure graphite powder containing 3·10-4% Ca, Mg, Ba, V, Mn, Zn, Cu, Co. Al, Be, Sc; the plasma zone reduced by a factor of three was imaged on the spectrograph slit. There are two analytical zones, which lie before and after jet merging; one can also use the merging; one can also use the merging region. Buffering with readily ionized component and low transport gas flows can be combined when the first region is used to determine trace elements. The atomic and ionic line peaks have height levels related to the excitation energies and optimum temperatures. The matrix effects vary between the zones, which must be remembered in choosing the working region. The two-jet plasmotron is advantageous in multielement direct or chemical-spectral analysis of mineral powders