AVS 53rd International Symposium
    Vacuum Technology Tuesday Sessions
       Session VT-TuP

Paper VT-TuP6
A Two-Stage Flow Divider System for the Test and Calibration of Vacuum Gauges

Tuesday, November 14, 2006, 6:00 pm, Room 3rd Floor Lobby

Session: Vacuum Technology Poster Session
Presenter: H. Yoshida, AIST, Japan
Authors: H. Yoshida, AIST, Japan
K. Arai, AIST, Japan
H. Akimichi, AIST, Japan
M. Hirata, AIST, Japan
Correspondent: Click to Email
Rapid generation of a stable vacuum pressure is necessary to evaluate characteristics of vacuum gauges. A two-stage flow divider system was developed to generate the stable vacuum pressure in high and ultra-high vacuum. This system mainly consisted of three parts, chamber 1, 2 and 3, which were connected in series using capillary A and capillary B. Chamber 2 for the gauge test was evacuated by a turbo molecular pump thorough orifice with the conductance of about 80 l/s. Chamber 1 is also evacuated by a turbo molecular pump, of which effective pumping speed is about 10 l/s, to reduce the gas flow rate from chamber 0 to chamber 2. The pressure P@sub 2@ in chamber 2 could be generated preciously by adjusting the pressure P@sub 0@ in chamber 0 using a pressure controller. P@sub 2@ was determined by P@sub 0@, the conductance of capillary A and B, and the effective pumping speed in chamber 1 and chamber 2. As P@sub 0@ was changed from 3.0x10@super 2@ Pa to 1.6x10@super 5@ Pa, P@sub 2@ was generated from 2.4x10@super -7@ Pa to 5.7x10@super -3@ Pa. P@sub 2@ reached stable within a few seconds and the fluctuation for 2.5 minutes was from 0.01% to 0.2%, which mainly depended on that of P@sub 0@. In addition, it was confirmed that the gas flow through capillary B was molecular flow because the pressure ratio of P@sub 2@ to P@sub 1@ was constant. Therefore, P@sub 2@ in lower pressure could be quantitatively determined from P@sub 1@ by using the P@sub 2@/P@sub 1@ ratio. This system is useful to evaluate characteristics of vacuum gauges. For example, it was found that the indication of ionization gauge was unstable for 600 s from the pressure setting.