Dynamic compact mass-spectrometer for in-line mode analysis of ITER fuel mixture. Preliminary tritium testing and calibration experiments

The positive peculiarities of the reflectron time-of-flight mass spectrometer (RTOF MS) at quantitative analysis of composition of tritium-containing gases are shown. A basic feature of the RTOF MS is pulse synchronous mode of extraction of ions from an ion source and unlocking of the detector. The operation in such mode practically eliminates a main disadvantage of mass spectrometric method of the analysis of tritium-containing gas mixtures - increasing of a background current of the detector connected with β-decay of tritium nuclei in continuous mode of operation. The laboratory model of the special RTOF MS for the analysis of ITER fuel mixtures is developed and tested in conditions of relatively short-term tritium experiment. Total duration of tritium experiments was about 12 hours. Increasing of an influence of background current during measurements was not observed. The calibration coefficients were stable. In the pressure range (1.10-5 - 5.10-3) Pa the apparatus has the linear sensitivity. All this facts confirm that the RTOF MS can be used as an effective and inexpensive instrument for on-line analysis of the fuel mixtures. (authors)