| AVS 56th International Symposium & Exhibition | |
| Vacuum Technology | Monday Sessions |
| Session VT-MoM |
| Session: | Vacuum Contamination and Pumping |
| Presenter: | P. Manini, SAES Getters, Italy |
| Authors: | P. Manini, SAES Getters, Italy C.D. Park, Pohang Accelerator Laboratory, South Korea S.M. Chung, Pohang Accelerator Laboratory, South Korea |
| Correspondent: | Click to Email |
Achieving a better base pressure and reducing bake-out time are the two important practices for an UHV system. Use of a sputter ion pump (SIP) in combination with non-evaporable getter (NEG) is one of the good solutions for this. Although many efforts have been made showing results of the pumping performances of NEG-SIP combination, the SIPs used were relatively large. Furthermore there is a demand for high performance, compact combination pumps that can be installed in a tight space in a storage ring of the proposed PLS-II project. Thus we tested the characteristics of a compact NEG-SIP combination pump (CNP) to see if the CNP can meet the above mentioned desires.
A compact getter cartridge mounted on CF40 flange (Capacitorr D 400-2) was used in combination with small SIPs, having speeds ranging from 10 to 60 l/s. The CNP was attached to a stainless steel chamber that has five CF40 flanges with a total inner surface area of 3,000 cm2.
Base pressures (BPs) of the CNP-UHV system, in a wide range of situations, with/without NEG and with/without baking were measured. Significantly lower pressures and faster pumping could be achieved using the CNP. Base pressures of low 10-11 mbar could be obtained with a compact NEG for 10 l/s and 60 l/s SIPs after a 48-h bakeout.
The results also show that the compact CNP can provide high pumping speed and reach 10-11 mbar after a very short (few hours) bakeout. The BP was 1x10-10 mbar with 60-l/s SIP alone after a 48-h bakeout, whereas it was 7.9x10-11 mbar with the CNP; a better result after only 2-h bakeout. This is quite a remarkable decrease in the bakeout time of a UHV system.
It is worthwhile to note that UHV could also be achieved with the CNP even in a fully unbaked system: A pressure of 3.9x10-10 mbar with the CNP was reached, while it was 8x10-9 mbar with the SIP alone. The other interesting result of the CNP-UHV system is that the pressure increase is much less and slower when the SIP is switched off. This is also a good characteristic, required for portable vacuum devices.
All these characteristics are particularly useful for the design and operation of the vacuum system of a storage ring. It may also be beneficial for the miniaturization of vacuum equipments and mobile applications which require smaller pumping systems.