Evolution of Vacuum Pressure in an Enclosed Chamber under Adsorption-Desorption Competition

The pressure evolution within an enclosed vacuum chamber is a dynamic process where material desorption and gas release compete with the adsorption of the getter. Accurate prediction of the pressure evolution is crucial for evaluating the lifespan of the device. Based on the adsorption dynamics theory and Fick's diffusion law, a coupled adsorption-desorption kinetic model including surface adsorption, in-body diffusion, and wall gas release was established. Using the COMSOL multi-physics software, with the boundary conditions of in-body diffusion gas release and getter adsorption, a numerical simulation method for the pressure evolution of the chamber was constructed. Taking a 304 stainless steel chamber as the research object, the wall gas release rate at different temperatures was measured by the static pressure rise method and the release characteristics parameters were fitted; the suction velocity characteristic curves of two ZrVFe non-evaporable getters were fitted to extract the adsorption dynamics parameters. On this basis, vacuum maintenance experiments under constant temperature and variable temperature conditions were carried out. The results show that an increase in temperature significantly increases the wall gas release rate and accelerates the pressure recovery rate; the simulation and experiments were in good agreement under both constant and variable temperature conditions, and the model can accurately reproduce the attenuation law of pumping speed with the increase in sorbed quantity. The research results can provide a reference for the optimization of the getter scheme and life prediction of enclosed vacuum devices.