New installation of in-vessel Non Evaporable Getter (NEG) pumps for the divertor pump in the LHD

Conceptual design of the Gas Injection and Vacuum System for DTT NBI

“…The conceptual design of the gas injection system, fore-vacuum group and turbo-molecular pumps for DTT NBI is well consolidated as it benefits from the large R&D and manufacturing experience of RFX [13]. On the other hand, the NEG technology has been applied only recently to fusion projects [14,15,17,18], hence we will focus the attention on this part of the system. • C, the vacuum vessel pressure will be higher than the equilibrium pressure, while during the regeneration phase, considered at 550 • C, the vacuum vessel pressure will be equal or lower than the equilibrium pressure.…”

Non-evaporable getter pump operations in the TCV tokamak

“…From recent tests [11], ZAO NEG pumps can withstand at least 1000 cycles with loads up to 18.6 mbar L per gram of getter material, which in the case of the CapaciTorr HV1600 [27], yields a limit of 13.8 bar L. Higher loads may not cause immediate damage, but may reduce the number of available cycles (further tests are required). Therefore, it is recommended that this limit must be avoided either by restricting the maximum possible single-experiment load, or by regenerating [11,12] the NEG by a thermal process (typically to around 550 o C) allowing the stored hydrogen isotope to be exhausted. In our experimental setup, we use a regeneration time of ≈ 11 hours.…”

“…The reactive species occupy possible D 2 adsorption sites of the ZAO [12,26] and lead to passivation, i.e. a degradation in D 2 pumping performance.…”

“…Recently, the development of the ZAO getter alloy [11] has opened new possibilities for experimental applications. For example, a design using several modules with ZAO was recently installed at the Large Helical Device (LHD) [12].…”

Application of Divertor Pumping to Long-Pulse Discharge for Particle Control in LHD

“…In the Large Helical Device (LHD), which is one of the largest helical experiment devices, the development of divertor pumping has been strongly enhanced since author's e-mail: motojima.gen@nifs.ac.jp FY2012. For divertor pumping, we applied cryo-sorption pumps [5,6] and non-evaporable getter pumps [7] in the divertor region. We found that divertor pumping contributes to a low recycling state in short-pulse discharges of five seconds or less in the LHD.…”