Low pressure plasma confined in a miniature cylindrical chamber and its application for in-situ elemental analysis

A unique miniature vacuum chamber made of a quartz tube has been devised for in situ spectrochemical analysis on samples with arbitrary curved surfaces. The dynamical analysis of the spatially integrated time profile of Pb I 405.7 nm and H. emission lines showed that the cylindrically confined plasma at a low pressure in the miniature chamber was generated by the shock wave mechanism. The result of measurement of standard samples with various chromium. concentrations showed an excellent linear calibration curve. Application of this new technique was carried out on a variety of samples having different shapes. It was found that the elements contained in the samples were clearly detected, including hydrogen impurities in the solid samples. It was further demonstrated that for samples with extremely rough surfaces, which prevent the attainment of low pressure, the use of helium gas flowing through the chamber instead of air still allowed the generation of low background plasma at atmospheric pressure.