Shinku

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An ultra-high vacuum mass spectrometer has been designed for the use of analyzing very small amount of gas samples and for the study of adsorption in ultra-high vacuum.
The mass spectrometer is of a single focussing type with a 60° magnetic sector field and a radius of ion orbit of 15cm, and the mass spectrometer components with masses between 1 and 200 a. m. u. can be identified. The analyzer system is made entirely of stainless steel and joined with oxygen free copper gaskets for vacuum seal similar to the Alpert's type.
The evacuation of the mass spectrometer is described in detail. The evacuating system includes oil rotary pumps, oil diffusion pumps, copper foil traps, ionization gauges, a getter ion pump, and all-metal vacuum valves. The sample introduction system, the analyzer system, the copper foil trap, and all-metal valves have been heated to 350°C by means of electric furnaces for outgassing, and then by the above pumping system our best vacuum to date has been 1.4 × 10^-8 mmHg by the Bayard-Alpert ionization gauge.
The background gases have been analyzed as a function of baking condition, and (12) ×10^-8 mmHg has been determined for background pressure at present.

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