Upon the basis of the axial-emission magnetron gauge (AEMG) a new axial-emission magnetron suppressor gauge (AEMSG) has been developed by adding a small photocurrent suppressor in front of the ion collector of AEMG. Due to the suppression of the residual photocurrent to the ion collector, the lowest measurable pressure (Px) of the AEMSG is reduced to ≲10−14 Pa (≲10−16 Torr) at I0=10−6 A, Us=500 V, and H=300 Oe. In comparison with other designs of hot-cathode ionization gauges, the AEMSG has some other advantages besides lower Px. It has a high sensitivity, its electrode construction is much simpler, so it is easier to degas, and its filament works at a lower temperature; these factors make the AEMSG more suitable for the measurement of extreme high vacuum. Furthermore, the upper limit of the AEMSG can be extended to 1.33×10−2 Pa (1×10−4 Torr) when the magnet is taken off and the emission current is increased to 1×10−3 A.
The axial-emission ionization gauge (AEG) has been modified to form an axial-emission magnetron ionization gauge (AEMG) by adding an axial magnetic field to the electrode construction of the AEG. This modification results in a much lower limiting measurable pressure. AEMG gives performances like that of Lafferty’s hot-cathode magnetron ionization gauge (LHMG) but the ratio of the x-ray photocurrent to the anode current Ix/Ia is smaller by more than two orders, so its lower limit is lower than that of LHMG. The upper limit of measurable pressure can be extended to 1.33×10−2 Pa (1×10−4 Torr) by operating the AEMG without the magnet. Since the electrode construction of AEMG is very simple, it is easy to de-gas and this is of benefit to its operation under extremely high vacuum.
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