電試質量分析計の真空排気系

概要

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Evacuating system of ETL mass spectrometer has been designed and constructed. In designing the system several points were considered so as to obtain the pressure in the analyzer tube below 1 ×10<SUP>- </SUP>m Hg and to keep the pressure constant. On the basis of the inquiry, following specifications were adopted : analyzer tube, all stainless steel ; evacuating system, two 4″ diffusion pumps with specially designed liquid-air cold traps and an oil rotary pump (250 <I>l</I>/min) as the fore pump ; baking, with Ni-Cr heater (300W) and by direct heating method (Transformer, 2KVA); monitoring system, available both for stoppage of electric current and suspension of water supply. Furthermore, a stainless steel gate valve was installed near the ion source (assembly) of the analyzer tube for the economy of evacuating time in the case of solid sample analysis. Results obtained with this system were described.