Metrological properties of an ionization gauge with carbon nanotube cathode in different gases

A novel CNT-cathode ionization gauge was developed in this work, and its vacuum metrological characteristics in different gases were studied systematically. A good measurement linearity between normalized ion current and gas pressure is achieved from 10−8 to 10−4 Pa in N2, H2, O2 and air, respectively, and the linear response region for He only lies in the range from 10−7 to 10−4 Pa. The lowest measureable pressure with this gauge is about 1 × 10−8 Pa in O2 gas, which is one order of magnitude lower than the reported same gauge type with CNTs cathode. It is also found that the gauge sensitivities are closely dependent upon gas species and anode voltage, and a high sensitivity factor as high as 0.205 Pa−1 is acquired for N2 under an anode voltage of 300 V, which is the first reported CNT-cathode ionization gauge whose sensitivity is higher than the parent hot cathode one.