IV. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 55 (2022)

RIKEN Accel. Prog. Rep. 55 (2022)

RILAC operation
T. Ohki,∗1 M. Fujimaki,∗2 N. Fukunishi,∗2 H. Hasebe,∗2 Y. Higurashi,∗2 E. Ikezawa,∗2 H. Imao,∗2 O. Kamigaito,∗2K. Kaneko,∗1 M. Kidera,∗2 M. Komiyama,∗2 R. Koyama,∗1 K. Kumagai,∗2 T. Maie,∗2 T. Nagatomo,∗2T. Nakagawa,∗2 T. Nishi,∗2 J. Ohnishi,∗2 H. Okuno,∗2 K. Oyamada,∗1 K. Ozeki,∗2 N. Sakamoto,∗2 K. Suda,∗2M. Tamura,∗1 A. Uchiyama,∗2 S. Watanabe,∗2 T. Watanabe,∗2 Y. Watanabe,∗2 K. Yamada,∗2 H. Yamauchi,∗1 andA. Yusa∗1
Originally, beam service was scheduled to start in January 2021. However, because of a failure owing to theaging of radio-frequency (RF) tanks of RILAC, repair of
the breakdown and preventive measures were performed
from January to March. In April, the external vacuum
windows and the vacuum ports were added to the RFtransmission line to energize the superconducting (SC)cavities, which were not used because of a vacuum leakage through the coupler ceramic windows. It operated
well and ten SC-cavities became available. A user beamservice started in May.
Some statistics regarding the RILAC operation fromJanuary 1 to December 31, 2021 are provided in Table 1.
Table 1. Statistics of RILAC operation from January 1 toDecember 31, 2021.

Operation time of RILAC

3294.0 h

Mechanical problems

185.4 hStandalone RILAC

2141.5 h

Injection into RRC

0.0 h

Total beam service time of RILAC(8) Introduction of automatic operation system of thecooling fans of the cooling towers for the ion sourceand the RFQ.
(9) Introduction of the automatic operation system of
the cooling fans of the cooling towers for SRILAC
and RILAC tanks with a function of alternating
operation control.
(10) Renewal of the GPIB control system of the magnet power supplies.
(11) Feasibility test of the gyrotron for newly constructed SC-ECRIS (R28G-K).
(12) Installation of the external vacuum windows andthe vacuum ports to the RF transmission lines of
the SC-cavities.
We encountered several machine troubles during thereporting beam service period, which are listed as follows.
(1) Signiﬁcant amount of coolant leakage from thedrift-tubes of the RILAC tanks.
(2) RF power shortage of the RF power source for RILAC tank #1 due to the aging of a power tetrode.
(3) RF power shortage of the 1st-stage RF ampliﬁer
for the RILAC tank #6.
(4) Abnormal RF ﬁeld error caused by the malfunctioning of the 1st-stage RF ampliﬁer.
(5) Leakage of the cooling water from the ﬁnal stage
ampliﬁer for RILAC tank #4.
(6) Burn out of the RF contacts for the shorting plateof the RFQ cavity due to a lack of cooling water.
(7) Leakage of the cooling water from the cooling pipeof the RFQ cavity.
(8) Leakage of the cooling water from the cooling pipe
adopted to the end drift-tube of the tank A1.
(9) Malfunction of the power source for the solenoid
coil (SoL11ab).
(10) Vacuum leakage from the bellows of the drive shaftof a mesh-beam-attenuator.
(11) Serious damage of the water pumps for the coolingsystem of the SRILAC RF ampliﬁers.

2141.5 h

We performed the following maintenance works during
the reporting period.
(1) Replacement of the leaky ﬂowmeters for the cooling channels of the drift-tube quadrupole magnets
in RILAC tanks and the quadrupole singlet magnets of the beam-transport-line.
(2) Rearrangement of the quadrupole magnets of theinjection transport line to the tank #1 to enhance
the transmission eﬃciency from the exit of theRFQ to the exit of tank #1.
(3) Renewal of the control and driving system of thecoarse frequency tuners of RILAC tank #3 andtank #4.
(4) Removal of the ﬁne frequency tuner of RILAC
tank #2 because of the vacuum problem.
(5) Development of the beam interlock system (BIS)
against the failure of the magnet power supplies.
(6) Construction of the quick BIS which instantly
chops the beam when there is an error of the RFcontrol system.
(7) Improvement of the rough evacuation ducts of theRILAC tanks by adding an automatic evacuation
system.
∗1∗2

All the troubles were successfully ﬁxed, and beam service was recovered instantly. The license of radiation
safety to use heavy-ion beams with an intensity of 10particle μA was updated after an inspection by the Secretariat of the Nuclear Regulation Authority.

SHI Accelerator Service Ltd.
RIKEN Nishina Center- 178 -1