Patent ID: 7872227

Claim:
A plasma mass spectrometer comprising: a plasma generating part for generating argon gas plasma into which a sample to be analyzed will be introduced, an interface that faces the generated plasma and that is used for sampling and then skimming a portion of the plasma, and an extraction electrode part that is found behind the interface and that is used for producing an ion beam behind the interface under reduced pressure from the skimmed plasma, said plasma mass spectrometer characterized in that a small collision chamber which is disposed between the interface and the extraction electrode part and is defined with a side wall which extends in an axial direction as it encloses the plasma in such a way that the expansion of the skimmed plasma to the side is restricted and with a flat electrode plate which is positioned behind the side wall at a distance capable of being reached by the skimmed plasma and has an opening through which the ion beam or plasma can pass such that the pressure is raised without introducing additional gas, and the argon ions in the extracted plasma are neutralized by a colliding and/or reacting effect caused by confinement in the small collision chamber and the ion density of the plasma is reduced.