Isotopic quadrupole mass spectrometry of hydrogen and helium

Analysis of isotopes of hydrogen and helium without radioactive components by quadrupole mass spectrometry (QMS) has been investigated for measuring the purity of deuterium for injection into the Tokamak of Strong Field. External radioactive source 24Na is used to imitate accompanying ionizing radiation of T2. A threshold magnitude of exposure dose power is found, the exceeding of which leads to the increase of detection limit and systematic errors of isotopic analysis. QMS is used at medium resolution of 300 to determine compositions of 3He in HD/H3 and 4He in D2/H2D, and to quantify impurities in the mass range from 1 to 22 amu. Analysis of 4He - D2 mixtures demonstrates the capability to measure isotopic composition with accuracy from 0.2 to 0.5%, depending on the sample-to-reference ratio of inlet pressure.