PURPOSE: To enhance the measuring accuracy of a vacuum meter, to keep sensitivity in repeated measurement and to reproduce sensitivity between a plurality of vacuum meters by selecting meter sensitivity fluctuating by the condition of the vacuum meter from data to correct the same.
CONSTITUTION: A cathode 16 extending in parallel to the axial line of an anode is provided to the outside of a cylindrical anode 18. An ion collecting electrode 20 is provided in an anode space along the inside of the radius of the anode within the range of 25-75% of the radius are provided to both end parts of the anode. A cathode heating current controller holding the electron discharge current from the cathode 16 to a predetermined value is provided. A memory part storing the calibration data group related to the current of the collecting electrode 20 and the sensitivity of the vacuum meter is provided. An operation part collating measured value of a collection electrode current with a calibration data group to calculate meter sensitivity to unknown atmospheric pressure and calculating the unknown atmospheric pressure corresponding to the calculated sensitivity, the measured value of the collection electrode current and the electron discharge current is provided.
MAIKERU DEIRU BOORENSUTAIN
POORU KURAAKU AANORUDO
