Research on Pumping Speed for Non-Evaporable Getter （NEG） on EAST

Particle exhaust is one of the key factors in controlling fuel recycling and enhancing plasma performance. The aim of this study is to evaluate the potential application of the Non-Evaporable Getter （NEG） in particle exhaust technology. The NEG pump is made of ZAO alloy materials, which is easy to install, operate, and maintain. It exhibits high pumping speed and capacity for hydrogen and its isotopes, and is compatible with the plasma environment. It is suitable for the divertor region with ultra-high heat flux and complex spatial structures. Four sets of HV800 modules have been installed in the EAST Tokamak, and regular pumping speed calibrations and regeneration studies have been conducted to assess its cyclic performance variations. The large surface area of the EAST vacuum chamber walls, along with gas emission and impurity gases from metal walls, impact the calculation of the pumping speed of the NEG pump. A method to correct the pumping speed of the NEG pump is proposed by calculating the overall leak rate and the outgassing rate of hydrogen and its isotopes in the EAST. A correction method for the pumping speed of the NEG pump is introduced by using computer simulations of the pumping process. The research results indicate that under the working pressure in the divertor region, the average pumping speed for deuterium can reach 1 200 L/s.