Abstract: The pumping speed measuring apparatus， which employs the flowmeter method， was introduced. The pressure was measured by using a spinning rotor gauge(SRG) under 1×10^-4 to 1×10^-2Pa， and the ionization vacuum gauge was used when the pressure was lower than 10^-4Pa. A method of measuring the pumping speed and the outgassing rate of the extractor gauge was given. The pumping speed and the outgassing rate of the extractor gauge were measured under the pressure of 10^-6 to 10^-4Pa. The flowmeter method was used to measure the pumping speed of the miniature sputter ion pump(SIP)in nitrogen and helium. The discharge state of the miniature SIP under different pressures was analyzed using COMSOL， and the experimental results were in good agreement with the theoretical analysis. The combined standard uncertainty of the flowmeter method was less than 4.4%.

Key words: sputter ion pump(SIP); low pumping speed; uncertainty; simulated analysis; penning discharge