Some problems of mass spectrometer for measurement of UF6

In case of using a mass spectrometer for measurement of UF6, it is necessary to take care of exhaust, because corrosive and adhesive sample gases are introduced into an analyzer tube. Unless the vacuum in the analyzer tube is sufficiently high and the ion accelerating voltage is high enough, the skirt of one peak of UF5+ is piled over the skirt of the other. Class bottles are not suitable for reservoirs of UF6, because UF6 is decomposed on the surface of glass wall by reaction and SiF4 will be produced. The structure of the source is that the ions are produced by electron bombardment on a jet flow of sample gas, which meets at a right angle with the electron beam. If the isotopic abundance ratio of U-235 is measured with the ion source by the method of single collector, the true abundance ratio is larger by 0.43% than the measured value from the chart of recorder in case of measurement with a natural sample. The isotopic abundance ratio measured by the zero-method does not need correction of the factor of √m1/m2' (where m1 and m2 mean masses of two sorts of molecules of UF6 respectively). (auth.)