PLASMA TORCH

摘要

A torch for producing an inductively coupled or microwave induced plasma for use in spectrochemical analysis. The torch includes a central tube ( 25 ) for conveying a flow of a gas carrying sample aerosol to a plasma ( 17 ) produced in the torch. The tube ( 25 ) has an inlet ( 31 ) and an outlet ( 39 ) of smaller size than the inlet and is shaped to deliver a substantially laminar flow of the gas at the outlet ( 39 ). The tube ( 25 ) is tapered along at least a substantial portion of its length such that its cross-section area gradually and smoothly reduces towards its outlet ( 39 ) along at least a substantial portion of its length. It has been found that such a tapered tube is resistant to obstruction by salts deposited from samples containing high levels of dissolved solids.