Design study of distributed pumping system using multilayer NEG strips for particle accelerators

The design study of a distributed pumping system using NEG (Non-Evaporable Getter) strips for the slender beam pipes of particle accelerators is presented. To achieve a high pumping speed and pumping capacity in a limited pumping space, a multilayer configuration of the NEG strips was considered. The number of strips was optimized by taking into account the conductance between the strips. An indirect heating method for activating the NEG strips was adopted to avoid short circuiting between them, and the effect of heaters on the pumping speed was studied. The temperature distribution in the strips during the indirect heating was simulated, and the heating power density necessary to activate the NEG strips was estimated. The temperature of the strips and the required heating power density for the activation process were experimentally measured using a trial model, and they were well in agreement with those obtained from the simulation. The trial model had a reasonable pumping speed for N2 after the activation process.