プリズム型質量分析計の設計と試作

概要

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A mass spectrometer consisting of two Q lenses and a prism magnet of 90° Kdeflection with parallel pole edges is designed and constructed. The radius of the ion trajectory in the magnetic field is 120mm. This optical system can make the instrument compact, as the magnet dimension can be chosen independently of resolving power. Three source or collector slits with different widths of 0.5, 0.1 and 0.02mm are mounted on a plate and one of them can be chosen according to the required resolving power. Two types of ion detector, i. e. a Faraday collector and an electron multiplier are placed behind two of the three collector slits and mass spectra are simultaneously recorded with different resolving power and sensitivity. The adjustment of the simultaneous focusing at two collector slits is achieved electrically by the rotation of a focal line. The resolving power obtained is 140, 670 and 3, 000, using the respective slit widths. The ion source sensitivity is 1 × 10 <SUP>-5</SUP> A/Torr.(Ie=100 μ A, Uacc=2, 500V, Res.=140)The ion accelerating potential is variable from 500 to 2, 500V with the stability of 10ppm/°C The magnetic field is scanned exponentially and mass spectra are plotted on a linear mass scale with a strip chart recorder driven by a pulse motor. The scanning time from M=11 to 500 is about 7 minutes.
日本質量分析学会の論文