II-8. Accelerator

RIKEN Accel. Prog. Rep. 55 (2022)

RIKEN Accel. Prog. Rep. 55 (2022)

Status of vacuum pumping systems in accelerator facilities
Y. Watanabe,∗1 M. Fujimaki,∗1 E. Ikezawa,∗1 O. Kamigaito,∗1 M. Kidera,∗1 T. Nishi,∗1 S. Watanabe,∗1K. Yamada,∗1 M. Nishida,∗2 K. Oyamada,∗2 J. Shibata,∗2 K. Yadomi,∗2 and A. Yusa∗2
been in operation for 35–43 years.3) Therefore, in theﬁscal year 2021, one 5000 L/s TMP is scheduled to be
updated in the RILAC and another TMP is scheduled
to be replaced by a set of smaller TMPs (800 L/s and1100 L/s).
A large RP in the SRC-RES4 (Resonator 4) has malfunctioned owing to age-related deterioration, and a newspare large RP has been purchased, which has not been
installed. In addition, some oil leaks in the small RPs
were repaired by installing new O-rings and seals asusual.
Malfunctions in the TPG have increased year by year.
The reason is unclear, but it is likely because of agerelated deteriorations. Three of the ﬁve malfunctioned
TPG controllers occurred when the power was restored
after an electrical power outage in August and October. This is one common pattern in malfunctions in vacuum pumping systems. Furthermore, all malfunctioned
gauges were replaced by spare units due to a contamination of the sensor head.
Regarding vacuum leaks at the RIBF, nearly all of
the vacuum leaks were caused by age-related deterioration and repaired by installing new O-rings or applying a repair material. For example, water leaks in thewater-cooling parts of the drift tubes in the RILAC cavities were repaired with a sealing agent, and multiple Orings were replaced with new parts. A water leak fromthe water-cooling pipe of a small compensation board in
the RILAC cavity #2 were also repaired with a sealingagent. A vacuum leak in the coupling of a lower feedthrough trim coil (C8) in the AVF was repaired witha sealing agent because it was diﬃcult to replace theO-ring.

A vacuum pumping system in the RIBF accelerator facility comprises cryopump (CRP) systems, turbomolecular pump (TMP) systems, rough pumping systems (mechanical booster pump + rotary pump [RP]),
additional chamber pumping systems (TMP + RP), andsubpumping systems (TMP + RP) as subvacuum of aresonator.1,2) In addition, module-type vacuum gauges(total pressure gauge [TPG] controller combined withtwo gauges) are used. In this paper, we report some
malfunctions of vacuum pumping system encounteredin 2021. Table 1 lists the malfunctions in the pumps,compressors, and gauges from 2018 to 2021. The vacuum pumping systems were relatively stable to maintainand manage in 2021. A malfunction of TMPs (including power supply) and RPs were less in 2021 comparedto other years. Additionally, malfunctions of CRP and
TPG increased in 2021.
Six cryopump compressors of the SRC malfunctioned
around the G01 Faraday cup (SRC deﬂection beam line)in the uranium beam for the BigRIPS experiments during the months of April to May. The malfunctions of thecryopump compressors were caused mainly in the SRC
room by a high environmental radiation dose. Therefore, we plan to relocate 13 compressors to a location
far (SRC-north area) from the region of high environmental radiation (SRC-south area) within a few years.
In addition, because the existing cryopump compressors (model; C30V, CRC-874) of the SRC and RRC
have been discontinued by the manufacturer and cannot repaired in the future, a new cryopump compressor(model; C30VRT, P-875CA) for the SRC and RRC has
been purchased as a spare unit in case of a malfunction.3)
Furthermore, because RRC cryopumps were manufactured in 1985 and the replacement of the cryopump to a
new model should be realized early, one unused cryopump system set of the IRC-valley cavity was relocatedto the RRC-valley cavity in 2020.3)
We must update large TMP systems (5000 L/s) in theRILAC and RRC within a few years because they have

Table 1.

References
1) S. Yokouchi et al., RIKEN Accel. Prog. Rep. 41, 101(2008).
2) Y. Watanabe et al., RIKEN Accel. Prog. Rep. 50, 154(2016).
3) Y. Watanabe et al., RIKEN Accel. Prog. Rep. 54, 79(2020).

Number of malfunctions from 2018 to 2021.

Number of units

2018

2019

2020

> 80

467TMP b)> 138

384RP c)

> 146

537

TPG d)> 160

469CRP a)

2021
6 (Pump)8 (Compressor)
1 (Pump)4 (Power supply)
1 (Pump)5 (Controller)
7 (Gauge)a) Includes a compressor. b) Includes an attached power supply. c) Excludes an oil leak. d) Includes
a controller, Pirani, and cold cathode gauge.
∗1∗2

RIKEN Nishina Center
SHI Accelerator Service Ltd.

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