A vacuum gauge is an instrument used to measure the degree of vacuum or air pressure. Generally, the measurement of air pressure is based on the changes in a certain physical effect under different air pressures. Widely used in scientific research and industrial production. The main component of a vacuum gauge is a hot cathode, and the heat emitted electrons generated during its operation ionize the gas. This ion flow is proportional to the number density of gas molecules. When all other parameters, including temperature, are constant, the size of the ion flow is proportional to the air pressure, and the air pressure value can be obtained by measuring the ion flow. The hot cathode ion gauge is mainly composed of three electrodes, namely cathode, gate, and collector.