The remote measurement of sulphur in steels by mass spectrometry

An experimental technique is described which enables steel to be typified by its sulphur content. A single laser pulse fired at the surface vaporizes a controlled amount of the sample. This is done in an oxidizing atmosphere such as air, or carbon dioxide, and sulphur dioxide is formed which can be pumped through a vacuum probe, typically 30 m long, and measured in a mass spectrometer. An expression is derived describing the shape of the pulse of gas obtained and the design and constraints are discussed. The detection sensitivity is 0.02% sulphur. A comparison is made between the theoretical performance and experimental results. Use of the technique in the core region of nuclear reactors is described. (author)