TORCH FOR INDUCTIVELY COUPLED PLASMA SPECTROMETRY

摘要

A torch for Inductively Coupled Plasma Spectrometry (ICPS) is formed from quartz and has inner and outer tubes defining an annular channel. The end of the inner tube is within an end portion of the outer tube, to define a chamber for a plasma ball. An inlet for a main gas flow opens tangentially into the annular channel. The annular channel is configured so as to maximize the swirl component of this flow. To this end, a connection to the inlet is provided with an annular toroidal shape, having a cross-section to or larger than the inlet. Further, the inlet is mounted relatively close to the end of the inner tube, so as to minimise decay of the swirl component as the gas flows along the annular channel, the length of the annular channel being sufficient to ensure that the flow leaving the annular channel is uniform and has a uniform swirl component. This arrangement enables a significantly reduced consumption of gas to generate a plasma ball, and can give improved performance, in terms of a higher detection rate in a spectrometer.