Testing and calibration of electronic ionization pressure gauges

Summary

• 1. The design of a manometric tube for electronic ionization pressure gauges must satisfy conditions (7) and (8) both within the limits in which it is calibrated and tested by means of a reference MacLeod gauge and over the required measurement range.

• 2. The cathode current I_k in the cathode circuit of ionization pressure gauges when the latter are being calibrated or tested must not exceed a certain value for which condition (16) holds and hence Eq. (15) is applicable. Systematic errors may otherwise occur, since the pressure in the system may differ considerably from that in the manometric tube.

• 3. The fulfilment of condition (16) may be checked indirectly by the shape of the curve representing a relationship of the type of (17). Conditions (16) are met over the linear portion of relationship (17). A deviation from linearity with a rising current I_k indicates a departure from conditions (16).

• 4. The above technique with the use of reference MacLeod gauges [9] provides a calibration and testing of ionization pressure gauges with a relative quadratic mean error in calculating their sensitivity of the order of 1–2%.