Design and optimization of a novel nonevaporable getter pump geometry

Nonevaporable Getter (NEG) pumps are widely used in complex vacuum systems to provide high and ultrahigh vacuum conditions, such as nuclear fusion reactors, accelerators, synchrotrons, and extreme ultraviolet photolithography. Compared to the turbomolecular pump and the cryogenic pump, the advantage of the NEG pump is that it has no moving component, works in a large temperature range, and is energy efficient without any cryogenics. In this study, a novel NEG pump geometry will be developed to exploit the topological enhance- ment effect of a simple design. It is demonstrated by means of the systematic Monte Carlo simulations that the enhancement factor is greater when the sticking coefficient is smaller, but the overall pumping speed of the NEG pump also depends on other parameters. After the geometric structure optimization, an NEG pump with a square cross section of 20 × 20 cm 2 can deliver a pumping speed of up to ∼2900 l/s for hydrogen at room temperature when the NEG sticking coefficient is 0.02, and the corresponding pumping speed of an NEG pump with a circular cross section of 20 cm diameter can deliver a pumping speed of up to ∼2100 l/s for hydrogen at room temperature.