Photon Factory Activity Report 2014 #32(2015) B

BL-13B/Beamline commissioning

Development of a Low-Cost, High-Performance
Non-Evaporable Getter (NEG) Pump
Kazuhiko Mase,1, 2, * Masato Tanaka,3 Naoya Ida,4 Hiraku Kodama,5 and Takashi Kikuchi1
1
Institute of Materials Structure Science, KEK, 1-1 Oho, Tsukuba 305-0801, Japan
2
SOKENDAI (The Graduate University for Advanced Studies), 1-1 Oho, Tsukuba 305-0801, Japan
3
Faculty of Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku 263-8522, Japan
4
Faculty of Science and Technology, Hirosaki University, 1 Bunkyocho, Hirosaki 036-8560, Japan
5
Faculty of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama
240-8501, JapanA low-cost, high-performance non-evaporable getter (NEG) pump was constructed using commercial
NEG pills comprising 70 wt% Zr, 24.6 wt% V, and 5.4 wt% Fe, a conflat flange with an outer
diameter of 70 mm (CF70), and a tantalum heater. After activation at 400 °C for 30 min, thepumping speeds of the CF70 NEG pump measured with the orifice method were 47–40, 8–6, 24–17,
and 19–15 L/s for H2, N2, CO, and CO2 gasses, respectively [1].
1 Introduction
Non-evaporable getter (NEG) pumps are ideal for
maintaining an ultra-high vacuum (UHV) of ≤10−8 Pa
because they have a high pumping speed in UHV, are oil
free, compact, lightweight, evaporation free, sputtering
free, sublimation free, vibration free, economical, andenergy saving. One of the most popular NEG materials is
an alloy comprising 70 wt% Zr, 24.6 wt% V, and 5.4 wt%
Fe developed and commercialized by SAES Getters under
the trademark of St 707 [2]. St 707 NEG can be fully
activated by heating to 400 °C for 45 min or to 350 °C forabout 24 h [3]. In the present paper, we describe a NEG
pump constructed of commercial NEG pills, a conflat
flange with an outer diameter of 70 mm (CF70), and atantalum heater. The pumping speeds of the CF70 NEG
pump measured with the orifice method [4] were 47–40,8–6, 24–17, and 19–15 L/s for H2, N2, CO, and CO2
gasses, respectively.
2 Construction and Evaluation of a NEG pump
We have constructed a NEG pump using 84 NEG
pills comprising Zr-V-Fe alloy, Zr 70 wt%, V 24.6 wt%,
and Fe 5.4 wt% (10 mm × 3 mm; Alvatec Alkali
Vacuum Technologies GmbH, APG-10-3-001-01, same
composition as St 707), two alumina tubes (1.2 mm ×0.8 mm × 100 mm), a tantalum wire (0.2 mm × 230mm), and a CF70 with electrical power feedthroughs asshown in Fig. 1. Titanium plates, rods, washers, screws,
and spacers are used to suppress outgassing and toimprove mechanical strength. The NEG pump can beactivated at 400 °C by heating the tantalum wire with acurrent of 2.8 A using a commercial electric powersupply.
Pumping speeds of the CF70 NEG pump weremeasured for H2, N2, CO, and CO2 gasses with the orificemethod [4] using the apparatus shown in Fig. 2. The

pumping speed (S) of the vacuum pump is given by thefollowing equation in the molecular flow region [4].
 P  P0 aS  C  a
 1 ,PP0b b
where Pa and Pb represent the pressure of the downstream
and upstream chambers measured by B-A gauges,
respectively, and P0a (P0b) is the base pressure of thedownstream (upstream) chamber. Since the orifice has adiameter of 10 mm and a thickness of 0.5 mm, theconductances of the orifice are 33.27, 8.89, 8.89, and 7.09
L/s for H2, N2, CO, and CO2 gasses, respectively, at 26 °C.
Measured pumping speeds of the CF70 NEG pump were
47–40, 8–6, 24–17, and 19–15 L/s for H2, N2, CO, andCO2 gasses, respectively.

Fig. 1 Schematic and photograph of the CF70 NEG pumpusing 84 NEG pills [1].

Photon Factory Activity Report 2014 #32 (2015) B

Fig. 2 Apparatus used for measuring the pumping
speeds of the NEG pump [1].
3 Conclusions
We have constructed an NEG pump using NEG pills
comprising 70 wt% Zr, 24.6 wt% V, and 5.4 wt% Fe,titanium parts, alumina tubes, a tantalum wire, and a
CF70 with electrical power feedthroughs. The NEG pump
can be activated at 400 °C by heating the tantalum wirewith a commercial electric power supply. The pumping
speeds of the CF70 NEG pump measured with the orificemethod were 47–40, 8–6, 24–17, and 19–15 L/s for H2,N2, CO, and CO2 gasses, respectively. The low-cost,high-performance NEG pump is a favourable alternative
to sputtering ion pumps in VSX beamlines. The NEG
pump can also be used for accelerators, front ends, endstations, and differential pumping systems.
Acknowledgements
This study was supported by a Grant-in-Aid forscientific research (KAKENHI: No. 26390070). The
authors are grateful to Prof. K. K. Okudaira (Chiba Univ.),
Prof. H. Kato (Hirosaki Univ.), Prof. M. Tanaka(Yokohama National Univ.), Prof. S. Ohno (YokohamaNational Univ.), Mr. A. Toyoshima (KEK-PF), Mr. H.
Tanaka (KEK-PF), Mr. H. Nishiguchi (BaroqueInternational Inc.), and Ms. E. Kazama (BaroqueInternational Inc.) for their invaluable advice and support.
References[1] K. Mase, M. Tanaka, N. Ida, H. Kodama, and T.
Kikuchi, AIP Conference Proceedings, submitted.
[2] C. Boffito, B. Ferrario, P. della Porta, and L. Rosai, J.
Vac. Sci. Technol. 18, 1117–1120 (1981).
[3] C. Benvenuti and P. Chiggiato, J. Vac. Sci. Technol. A14, 3278–3282 (1996).
[4] M. H. Hablanian, J. Vac. Sci. Technol. A 5, 2552–2557 (1987).
*mase@post.kek.jp