Ⅱ-8. Accelerator
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Activation of temperature control in the RILAC cooling water
K. Yamada,∗1 M. Tamura,∗2 A. Yusa,∗2 and N. Sakamoto∗1∗1∗2

control of the heat exchanger bypass valves in the resonator and irradiation vault systems was enabled, andboth systems were maintained within ±0.2◦ C.
The SRILAC system was originally a cooling system for the RILAC booster, but the automatic controlof the ﬂow control valve had been disabled since thewater leak in 2009. The control panel was modiﬁed
to enable automatic ON/OFF control of two fans alternately, and automatic control of the primary temperature control valve was enabled. As a result, thetemperature could be controlled to ±0.1◦ C.
The vacuum pump system used a closed cooling
tower. Previously, the system froze during the cold
winter, requiring repair. Thus, the control panel wasmodiﬁed, and a temperature controller was added.
Currently, the temperature is controlled at 23 ± 2◦ C,
and there is no longer any concern about over-cooling.
Figure 1 shows an example of one day trend for rf
voltage and phase in the RILAC resonators. The rf
stability is dramatically improved after activating thetemperature control, contributing to a further intensebeam supply and increased availability.
RF1 voltage

RF2 voltage

RF1 phaseRF2 phase

Water temperature
29.0

1.00202021/06/05
Fluctuation [normalized]

1.001528.5
28.0

1.001027.5
1.000527.0

1.000026.5

0.999526.0
25.5

Temperature [Υ]Fluctuations in cooling water temperature have asigniﬁcant impact on the accelerator. For example, achange in water temperature deforms the cavity resonator of the accelerator and changes its resonant frequency, resulting in a slight drift in rf voltage andphase despite feedback control. This aﬀects the beam,causing beam loss and making it diﬃcult to maintain ahigh-intensity beam. Therefore, we decided to activate
the temperature control of the cooling water system ofRILAC to realize a high-intensity beam and improveavailability.
The cooling water of the RILAC is roughly divided into the ion source system, RFQ1) system, RILAC2) main system, RILAC booster3) /SRILAC4) system, and vacuum pump system. Except for the vacuum system, the secondary cooling water was cooledin the cooling tower, and the primary cooling water,which recovers heat from the load, was cooled througha heat exchanger. Some systems had ﬂow control
valves for temperature control, but the majority ofthem were disabled. In addition, all the fans in thecooling tower were constantly rotating, and the temperature of the secondary water ﬂuctuated greatly depending on the condition of the outside air. As a result,
the temperature of the primary water changed several
degrees in one day.
The ion source system was originally temperaturecontrolled, but the cooling tower fan was rotated constantly. This secondary water was also used for theRILAC drift tube cooling system, and the temperature drop in winter caused a vacuum leak from thedrift tube, resulting in a severe discharge. Therefore, atemperature controller was added on the control panel
to automatically turn fans ON/OFF at 24 ± 1.5◦ C.
The RFQ system had a heat-exchanger bypass valve
on the secondary side, which was sticking and unusable. The control panel was modiﬁed to add a primaryand secondary temperature controller, and the bypass
valve was replaced with a new one. The cooling tower
fan is now automatically controlled ON/OFF at 23 ±1◦ C, and the primary temperature automatically controls the bypass valve to keep at about ±0.1◦ C.
The secondary cooling water in the RILAC main system cools the resonator system, ampliﬁer system, andirradiation vault system as the primary side. The number of cooling tower fans can be controlled by adding
a temperature controller and rewriting the logic controller program by automatically turning them on andoﬀ individually. In addition, the fans are activated insequence to reduce damage due to startups. Automatic

0.999025.0
0.998524.5

0.998024.0

0:00:00 2:00:00 4:00:00 6:00:00 8:00:00 10:00:00 12:00:00 14:00:00 16:00:00 18:00:00 20:00:00 22:00:00 0:00:00

RF1 voltage

RF2 voltage

RF1 phaseRF2 phase

Water temperature
29.0

1.00202023/01/23

28.5
28.0

1.001027.5

1.000527.0

1.000026.5

0.999526.0

25.5

Temperature [Υ]Fluctuation [normalized]

1.00150.999025.0

0.998524.5

0.998024.0

0:00:00 2:00:00 4:00:00 6:00:00 8:00:00 10:00:00 12:00:00 14:00:00 16:00:00 18:00:00 20:00:00 22:00:00 0:00:00

Fig. 1. One day trend of rf voltage and phase in the RILAC
resonator no.1 and no.2 before (upper panel) and after(lower panel) stabilizing the water temperature.

References
1) O. Kamigaito et al., Rev. Sci. Instrum. 70, 4523 (1999).
2) M. Odera et al., Nucl. Instrum. Methods Phys. Res. A
227, 187 (1984).
3) O. Kamigaito et al., Rev. Sci. Instrum. 76, 013306(2005).
4) K. Yamada et al., Proc. SRF2021, (2021), p. 167.

RIKEN Nishina Center
SHI Accelerator Service Ltd.

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