Mass spectrometry of plasmas.

The application of mass spectrometry to plasma diagnostics from about 1965 to the present is reviewed. Two major areas where mass spectrometry has had a substantial impact are clearly identified: (1) The partial pressure analysis of neutral gases from fusion plasmas, where the major consideration is the ejection of wall materials or adsorbates into the gas phase. (2) The flux analysis of charged or neutral species from process plasmas, where the principal objective is the deposition of a film with special properties, or the etching of selected materials. This treatise is limited to the quadrupole mass spectrometer since its use is so widespread in either fusion or process plasma diagnostics. Energy selection and the ion optical coupling at the quadrupole are emphasized for flux analysis of ions. The need and techniques for absolute calibration in partial pressure analysis and in flux analysis of neutrals is also emphasized. The emergence of computer simulations as the most appropriate method for data interpretation of flux analyses is discussed.