Mass spectrometer for accurate hydrogen isotopic analyses

A theoretical study of the mass spectrometric analysis of mixtures of the hydrogen and helium isotopes shows that mass discrimination and low ion intensity in ion sources are the principal factors that limit accuracy. A virtual-image ion source with short focal length and high brightness avoids these limitations. Suitable analyzers and accessory equipment are available. Development and construction of an ion source with the required characteristics are within the state of the art of mass spectrometry. A high-resolution mass spectrometer with a satisfactory ion source should routinely analyze mixtures of the hydrogen and helium isotopes accurately within +-0.5 percent relative (99.7 percent CL) with ordinary operating techniques. Isotopic equilibrium, auxiliary helium analyses, and accurate standard would not be needed. Analyses accurate within +-0.3 percent relative (99.7 percent CL) could be made by using accurately mixed standards