II-8. Accelerator

RIKEN Accel. Prog. Rep. 54 (2021)

RIKEN Accel. Prog. Rep. 54 (2021)

Status of vacuum pumping systems in accelerator facilities
Y. Watanabe,∗1 E. Ikezawa,∗1 M. Fujimaki,∗1 S. Watanabe,∗1 K. Yamada,∗1 M. Nishida,∗2 K. Oyamada,∗2J. Shibata,∗2 K. Yadomi,∗2 and A. Yusa∗2Vacuum pumping systems in accelerator facilities havethe following two problems: vacuum leakage and update
issue. The vacuum leakage is a malfunction of old accelerator facilities caused by age-related deterioration. Theupdate issue is that almost all old vacuum pumps andaccessories cannot be replaced with new units owing to abudget limitation. In this paper, we discuss the current
status of vacuum pumping systems.1,2)
A vacuum pumping system in an accelerator facility1) comprises cryopump systems, turbomolecular pump(TMP) systems, rough pumping systems, additional
chamber (AC) pumping systems, and subpumping systems (subvacuum of a resonator). Table 1 lists the number of vacuum pumping systems in accelerator facilities.
Each ring cyclotron contains more than 80 sets of cryopump systems,2) more than 120 sets of TMP systems, and
2–8 sets of rough pumping, AC pumping, or sub-pumping
systems. In addition, more than 160 module-type vacuum gauges (total pressure gauge controller) combinedwith Pirani and cold cathode gauges are used to monitor
vacuum pressure and interlocking vacuum process control in accelerator facilities. Table 2 lists the number ofmalfunctions in the pumps and gauges from 2018 to 2020.
In a year, three to nine malfunctions occur in each unit.
The number of malfunctions may have been lower before
2017 because of the shutdown of the RILAC due to theSRILAC installation in 2017–2019 and the closure of theRIBF due to the COVID-19 pandemic in 2020.
Vacuum pumping systems have been in operation for
14–42 years.2) In particular, RRC cryopumps, large RILAC TMPs (5000 L/s), and large RRC TMPs (5000 L/s)
were manufactured in 1985, 1978–1987, and 1985, respectively. In addition, the doses in the SRC, IRC, and AVF
room are extremely high during beam irradiation. Therefore, the number of malfunctions caused by age-related
deterioration and environmental radiation will increasefurther in the future. New spare units of vacuum pumping systems were purchased gradually, but these spareunits are still not suﬃcient. The following requirements
remain.
(1) All the existing RRC cryopump compressors havebeen discontinued by the manufacturer; therefore,

Table 2. Number of malfunctions from 2018 to 2020.
Cryopumpa
Turbomolecular pumpb
Rotary pump
Vacuum gaugec

201843542019
68362020
7479

a Includes a compressor. b Includes an attached power supply.
c Includes a controller, Pirani gauge, and cold cathode gauge.

at least six cryopump compressors must be replaced with new ones within a few years. Basedon such measures, one cryopump system set of theIRC-NE valley cavity was relocated to the RRC-VSvalley cavity in 2019, and two cryopump systems
operate in the IRC-NE valley cavity. Six SRC cryopump compressors should be also replaced withnew ones in the future.
(2) In the case of large TMPs, although one 5000 L/s
TMP of the RRC was replaced with a new one
in 2017 and one of the RILAC is scheduled to beupdated, the other 5000 L/s TMPs are not yetscheduled for replacement. In addition, a few malfunctions of large rotary pumps (RPs) have been
occurring in the rough pumping system of ring cyclotrons and have not been repaired. Therefore,
these large RPs must be replaced with new units
in the future, although their operating times arelower.
However, small TMPs and RPs as well as vacuum
gauges have been repaired or updated, and these havebeen relatively stable. Oil leaks in small RPs were mainly
repaired by replacing new O-rings and seals, and vacuum
gauges were repaired by replacing some boards and parts.
Consequently, if more cryopumps or TMPs malfunction in a year, it will be diﬃcult to operate accelerator
facilities depending on the number of spare units. Therefore, the priority would be to purchase a suﬃcient number of spare units.
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).

Table 1. Number of vacuum pumping systems in accelerator facilities.
Cryopump system
TMP system (TMP + RP)
Rough pumping system (MDPe + RP)
AC pumping system (TMP + RP)
Sub-pumping system (TMP + RP)
Module-type vacuum gauge

RILACa1114−−−
16RILAC2a AVFa
82111−
−
−−−
−
91RRC
1442d4−
14fRC
622−
−
3IRC
14b4d24414SRC
224d2−
810BTa
3c
78−
−−
78

a Excludes ion sources, SRILAC, or charge strippers. b One set was relocated to RRC. c Includes a re-buncher and D6-BEA.
d One is out of order or oﬄine. e Mechanical booster pump.

∗1∗2RIKEN Nishina Center
SHI Accelerator Service Ltd.

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