Abstract: In this paper, an indirect cavity pressure measuring method for small semitight device is presented, which is based on characteristics of cavity pressure unable to be directly measured by the vacuum gauge. This method is combined with principle of constant volume method and constant conductance method, which are used in vacuum materials outgassing rates field. For a typical semitight devices, simulation test and comparison work utilize the above method and microssensor in-situ method are carried out. The simulation test results show that the as-proposed cavity pressure detection method is simple and accurate, and can solve the problem of pressure cavity and change of semitight devices. This method is applicable to the real-time monitoring of cavity pressure changes during the process of filling oil of gyroscope, filling helium of mechanical refrigerator and filling xenon of electric propulsion system.

Key words: semitight device, pressure change, detection method