Development of non evaporable getter pumps for large hydrogen throughput and capacity in high vacuum regimes

Sartori, E.; Siragusa, M.; Sonato, P.; Siviero, F.; Mura, M.; Maccallini, Enrico; Ferrara, Augusto M; Manini, Paolo; Hanke, S.; Day, Christian

doi:10.1016/j.vacuum.2023.112198

Cited by 3 publications

(1 citation statement)

References 44 publications

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“…As mentioned, the vessel pressure influenced the discharge probability when operating the RF drivers with multiple generators. The new pumping system was designed on the basis of Non Evaporable Getter technology [47], as recently developed [48]. The large pump, composed of many independent cartridges, will be installed behind the ion source, and requires the integration of thermal shields to protect in-vacuum components during high-temperature regeneration of the pump.…”

Section: Expected Conditions With Improved Pumping Systemmentioning

confidence: 99%

Highlights of recent SPIDER results and improvements

Sartori,

Agnello,

Agostini

et al. 2023

J. Inst.

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Three years of experiments on SPIDER allowed characterization of the main features of the source plasma and of the negative ion beam, in the original design configuration. For the large dimensions of the source chamber, and of the extraction area, the investigation of the single-beamlet currents and of the source plasma uniformity had to be carried out to extend the knowledge gained in smaller prototype sources. The configuration of the multiple RF drivers and filter field topologies were found to cause a peculiar behavior in the plasma confinement in the drivers, creating left-right asymmetries which were also visible in the extracted negative ion currents, even after the early implementation of a new scheme of plasma-grid current send and return busbars that greatly improved performance at high filter fields. The plasma properties in the driver and expansion region as well as the positive ion energy at the extraction region were studied in different experimental conditions, and interpreted also with the support of numerical models, suggesting that an improved plasma confinement could contribute to the increase of the plasma density, and to a certain extent to a lowering of the plasma potential profile; both effects shall contribute to increase the presence of cold negative ions for the formation of low-divergence beamlets. Early results related to unwanted RF discharges on the back of the plasma source and the gas conductance of the beam source suggested the reduction of the vessel pressure as mitigation, leading to the definition of a new pumping system. The difficulties related to the simultaneous operation, stable control and high-power operation of multiple RF self-oscillating vacuum tube based RF generators were an unambiguous obstruction to the experimentation, calling for the implementation of RF solid-state amplifiers. The initial tests related to caesium management, the non-uniform plasma properties at different locations across the plasma grid, and the challenges in the measurement of the current and divergence of the accelerated beamlet, unambiguously resulted in the need of new diagnostic systems to investigate with better resolution the spatial uniformities. This contribution summarises how the main experimental findings in the previous experimental campaigns are driving modifications to the SPIDER experiment, during the present shut down, in view of future operations.

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Section: Expected Conditions With Improved Pumping Systemmentioning

confidence: 99%

Highlights of recent SPIDER results and improvements

Sartori,

Agnello,

Agostini

et al. 2023

J. Inst.

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The Preliminary Results of the Pumping Speed Measurements of UHV Pump Based on the NEG for Hydrogen and its Isotopes

Semenov,

Krasnov,

Idashin

2024

2024 IEEE 25th International Conference of Young Professionals in Electron Devices and Materials (EDM)

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Experimental Characterization of an NEG Pump of Novel Size—A Major Step toward Its Application in DEMO Neutral Beam Injectors

et al. 2023

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A future nuclear fusion plant DEMO needs neutral beam injection (NBI) systems requiring a vacuum pumping system with a very high pumping speed, in the order of several 1000 m3/s. Large customized cryopumps are actually used to meet the requirements. A promising concept for future NBI systems is based on high capacity getter materials. The ZAO® alloy, developed by SAES Getters, Italy, provides a drastically improved performance for the pumping of hydrogen compared to conventional getter materials. This paper describes the experimental characterization of a large pump of scalable size with 15 kg of ZAO® and the achieved results, in particular the systematic investigation of sorption characteristics and regeneration behaviors. Major findings include a very good repeatability of the sorption performance, a reduced pumping speed at higher pressures only above the NBI relevant level, an improved performance (+20%) with elevated getter temperature and an isotope independent sticking coefficient for hydrogen. Furthermore, improved operation experience and regeneration prediction tools have been developed. Employing the experimental results, a simulation task was performed and the sticking factor of the getter cartridge was determined with 7%.

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Development of non evaporable getter pumps for large hydrogen throughput and capacity in high vacuum regimes

Cited by 3 publications

References 44 publications

Highlights of recent SPIDER results and improvements

Highlights of recent SPIDER results and improvements

The Preliminary Results of the Pumping Speed Measurements of UHV Pump Based on the NEG for Hydrogen and its Isotopes

Experimental Characterization of an NEG Pump of Novel Size—A Major Step toward Its Application in DEMO Neutral Beam Injectors

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