CALIBRATION OF VACUUM-SYSTEMS BY GAS QUANTITIES

A calibration method for the hv- and uhv-range with accuracies comparable to those of a capacitance manometer is discussed. Calibrations are performed by expanding known gas quantities under dynamic pumping conditions. The quantity of gas is defined by the pressure (measured by means of a capacitance manometer) inside a small calibration chamber (volume = 27 cm3) at a known temperature. Pure gases as well as gas mixtures can be used. The method is applied primarily for calibration of gas-quantity measurements. In this case the gauge-sensitivities as well as the effective pumping speeds need not be calibrated separately. The method may also be used for calibration of pressures and of gas-flow rates.