水銀拡散ポンプの排気速度

概要

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The pumping speed was measured for a pumping system which consists of three traps, a mercury diffusion pump and a rotary pump in series, using a flow-pipe of conductance Sf. The correct value of the speed S can be obtained if the sample gas partial pressures at the inlet and outlet side of the pipe. are used forPs and Pe in the formular S = Sf (Ps/Pe-1). On the contrary the use of the total pressures as indicated by the ionization gauges will give rise to smaller values of S, especially when theresidual gases begin to predominate at lower pressures. Consistent values of S have been obtained by using for Ps and Pe the pressure increments Ps and Pe as indicated by the ionization gauges each time when the flow rate of the sample gas was changed stepwise from zero or vice verse. This procedure is free from the interference due to the back diffusion of the sample gas. The result is that in the pressure range from 1×10-5 to 1×10-10mmHg the pumping speed of the present system for the sample gas maintains the same value. This is reasonable because no change of pumping mechanism is to be possible over the whole range of pressure.
日本真空協会の論文