WEOAM05
KEK, Tsukuba, Japan
Yokohama National University, Yokohama, Japan
University of Tokyo, Kashiwa, Japan
Yokohama National University, Graduate School of Engineering Science, Yokohama, Japan
Nonevaporable getter (NEG) pumps are widely used to maintain ultrahigh vacuum (UHV). Commercial NEG pumps using ZrVFe alloy can be activated by heating at 400¿500 °C, and pump active residual gases such as H₂, H₂O, CO₂, CO, N₂, and so on at room temperature (RT).* Recently T. Miyazawa, T. Kikuchi, K. Mase et al. have developed a new NEG, Pd overcoated on Ti thin film with a purity higher than 99.95% (oxygen-free Pd/Ti hereafter), which pumps H₂ and CO at RT after baking at 133 °C for 12 hours.** Then we developed a zero-length conflat flange NEG pump deposited with oxygen-free Pd/Ti.*** The NEG pump can be fully activated by baking at 150 °C for 12 h and exhibits initial pumping speeds of 2340 L s¿1 for H₂, and 1440 L s¿1 for CO. The initial pumping speeds of the oxygen-free Pd/Ti thin film after baking at 150 °C were estimated to be 3.2 L s¿1 cm¿2 for H₂ and 7.6 L s¿1 cm¿2 for CO. The present NEG pump is ideal for maintaining UHV below 10¿8 Pa, because its pumping speeds for H₂ and CO are quite large, and because it can be fully activated by baking at 150 °C for 12 h.
*E. Maccallini et al., AIP Conf. Proc. 1451, 24 (2012).
**T. Miyazawa et al., J. Vac. Sci. Technol. A 36, 051601 (2018).
***Y. Sato et al., Vacuum 212, 112004 (2023).
WEPPP042
KEK, Ibaraki, Japan
Sokendai, The Graduate University for Advanced Studies, Tsukuba, Japan
Sokendai, Ibaraki, Japan
University of Tokyo, Kashiwa, Japan
Tsukuba University, Ibaraki, Japan
Nonevaporable getter (NEG) pumps are widely used in synchrotron radiation facilities because they are oil-free, vibration-free, space-saving, lightweight, and energy-saving. When a NEG thin film is deposited on the inner wall of a vacuum duct, the residual active gases are pumped after baking. Recently we have developed a new NEG thin film that was prepared by the following simple procedure, sublimation of high-purity Ti under UHV in the range of 10-7 to 10-8 Pa, followed by N₂ introduction.*,** We confirmed that partially nitrided high-purity Ti coating on inner surface of a vacuum vessel pumped H₂, H₂O, O₂ gases, and CO even after 30 cycles of pumping, baking at 185 °C for 6 hours, cooling down to room temperature, introduction of high-purity N₂, and exposure to air.** In the present study, we applied surface-partially nitrided high-purity Ti on the inner surface of the vacuum ducts in the upstream section of BL-12C in the Photon Factory 2.5 GeV ring and baked them at 250°C. Pressure in the section reached ultrahigh vacuum of 2.2×10-8 Pa without ion pumps after isolation from the turbomolecular pump with gate valve.
* T. Miyazawa et al., Vac. Surf. Sci. 61, 227 (2018).
** K. Mase, et al., MEDSI2020 Proceedings, TUPA01 (2021)