IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Vacuum Science & Technology Thursday Sessions
       Session VST3-ThP

Paper VST3-ThP7
Computer Applications in Vacuum Measurement

Thursday, November 1, 2001, 5:30 pm, Room 134/135

Session: Vacuum System Modeling Poster Session
Presenter: D. Tian, Lanzhou Institute of Physics, P.R.China
Correspondent: Click to Email

Study of vacuum measurement has been developed in our laboratory for over thirty years. Measurement standard apparatus of total pressure, partial pressure and flow (leak rate) were constructed successively. They are used to calibrate the vacuum gage, mass spectrometer, leak and flowmeter. Computer technology is used widely in these fields. With the aid of computer, these projects can proceed successfully and efficiently. Some application examples are introduced in this article. Computer simulation was used to solve some theoretical problems in vacuum measurement. By means of Monte-Carlo method and view-factor method the computer simulations were accomplished in nonuniform molecular flow field of dynamic flow method calibration system and relative calibration system. Computer can complete complicate scientific calculation easily. Static expansion apparatus is an absolute vacuum standard and needs a great deal of formula calculations for the correction of pressure, volume, and temperature. Computer can provide a real-time value of actual pressure so as to find measurement problems in time. In order to improve control accuracy, manual operation has been replaced by computer automatic control gradually. According to the principle of negative feedback and algorithm of proportional integral differential (PID) control, the fluctuation of pressure in variable chamber was controlled within ±0.01% by a computer adjusting the piston displacement. This technology enabled us to manufacture a high precise constant pressure flowmeter. Computer can not only control and safeguard vacuum pumps, valves and gauges, but also acquire and manage measurement data. Comparison method apparatus calibrates vacuum gages automatically with high efficiency by using interface communication and logical control. With further application of computer technology, vacuum measurement technology will progress rapidly in the future.