Proceedings of the 19th Annual Meeting of Particle Accelerator Society of Japan
October 18 - 21, 2022, Online (Kyushu University)

PASJ2022 THP027

INTRODUCTION OF ACCELERATOR KNOW-HOWS TO
KAGRA'S VACUUM SYSTEMMin Yang†, Norihiko Kamikubota, Takashi Asami1, Shuei Yamada, KEK/J-PARC, Japan
Takayuki Tomaru, NAOJ, Japan
Takashi Uchiyama, ICRR, JapanKAGRA Collaboration1
also at University of Tokyo, Japan
Abstract
KAGRA is a large-scale cryogenic gravitational wave
telescope in Japan. In March 2023, next collaborative observation on gravitational waves will start. The stable operation of pumps, gate valves and gauges in KAGRA vacuum system is critical, while there has been less effort todevelop a remote monitoring system for them. We developed a small EPICS-based vacuum monitoring system for
KAGRA as a prototype, which simulates the vacuum control system of J-PARC Main Ring.
The system consists of a micro-server, a MOXA serial
device server, and a PLC controller with I/O modules. The
micro-server works as an EPICS IOC. The MOXA connects a gauge (CC-10) and an ion pump (Digitel MPCq).
The PLC I/O modules accept on/off/fault signals of a roots
pump and a turbo molecular pump, and open/close signals
of gate valves.
In February 2022, this vacuum monitoring system wasinstalled and tested successfully in the KAGRA tunnel.
During the FY2022, we proceed to increase the number ofremote monitoring stations.

INTRODUCTION
The Kamioka Gravitational Wave Detector (KAGRA) isa large-scale cryogenic gravitational wave telescope ofICRR (Institute for Cosmic Ray Research of University ofTokyo). The KAGRA is located in Kamioka, Hida, Gifu
Prefecture, Japan [1]. The early joint observation withGEO600 was carried out in April, 2020 [2]. The next isplanned to be a collaborative observation between LIGO,
VIRGO, and KAGRA, which is called “O4”. It will start inMarch 2023.
Since 2020, there is an MOU between KEK (High Energy Accelerator Research Organization) ’s accelerator division, NAOJ (National Astronomical Observatory of Japan), and ICRR, with which KEK is asked to provide suggestions on cryogenic, vacuum and control systems of KAGRA. Since 2021, the control staff of KEK/J-PARC visited
KAGRA site, and discussed with the KAGRA staff about
the control system of KAGRA.
As we all know, the stable operation of pumps, gatevalves and gauges in KAGRA vacuum system is critical.
However, there has been less effort to develop a remotemonitoring system for them. In fact, there have been cases
where a pump stopped without being aware of it. Toward

the “O4”, to develop a remote monitoring system of vacuum devices is very important.
Therefore, during the second half of FY2021, we (KEK)
developed a prototype of vacuum monitoring system for
KAGRA, which simulates the vacuum control system ofaccelerator facility J-PARC (Japan Proton Accelerator Research Complex) Main Ring.

DESIGN OF PROTOTYPE VACUUM
MONITORING SYSTEM
BackgroundThe digital control system of KAGRA was introduced
from LIGO. The slow control part of the system is basedon an open-source framework, EPICS (Experimental Physics and Industrial Control System) [3]. Thus, the KAGRA
vacuum system is planned to use EPICS. However, KAGRA staff has less development experience of EPICSbased systems.
The control system of J-PARC Main Ring is EPICSbased, which was developed in 2006 [4] and has been running steadily ever since. To develop the KAGRA vacuum
system faster, know-hows of the J-PARC control system
are used.

Hardware
The goal of the KAGRA vacuum system is to monitor
the status of pumps, gate valves, and gauges. To achievethese objectives, a commercial micro-server (Pinon Sabataro Type-P), which is a standard component of the JPARC control [5], is introduced as an EPICS IOC (Input
Output Controller). A MOXA serial device server (RS485LAN converter) and a PLC controller (Yokogawa F3MA)
are used to realize the communication between vacuum devices and the IOC. The structure of the system is shown inFig. 1.
The gauge (CC-10 controller) has a RS485 serial interface. To monitor vacuum pressure in Torr, a MOXA serveris used to convert the RS485 to LAN port, then connectedto the KAGRA local network for data monitoring.
Vacuum devices with digital I/O only, such as Gate Valve(GV), Turbo Molecular Pump (TMP), and Roots Pump, areconnected to a control box, which is designed for handlingmetal signal cables. Then a PLC controller accepts
On/Off/Fault signals of a roots pump and a TMP, andOpen/Close signals of gate valves. The PLC is also connected to the KAGRA local network.

____________________________________________† yangmin@post.kek.jp- 780 -Proceedings of the 19th Annual Meeting of Particle Accelerator Society of Japan
October 18 - 21, 2022, Online (Kyushu University)

PASJ2022 THP027

Figure 1: The structure of prototype monitoring system of KAGRA.
In addition, an ion pump (MPCq controller) has both a
RS485 port and an ethernet port. To realize ion pump monitoring, a MOXA server can be used as the CC-10, but direct ethernet connection to the KAGRA local network isalso possible.
The micro-server has two ethernet ports. One of the ports
is connected to the KAGRA control network. Another port
is connected to the KAGRA local network for data collection and for system development and test.

and a ladder CPU module. The digital signals of gate
valves and pumps are transferred to the PLC I/O modules
through the control box, then monitored by Saba-taro
server through the KAGRA local network.

Software
The basic environment of EPICS is imported from the JPARC control system. The operating system of a microserver is CentOS 7. An EPICS IOC is running on it.
Some EPICS modules are used for realizing the communication between devices and a micro-server. For example,
EPICS StreamDevice [6] is used for serial communication
with MOXA servers; netDev [7, 8] is used for PLC-EPICS
communication. Within the PLC, Ladder program is embedded to realize monitoring functions of pumps and gatevalves.

DEMONSTRATION

Figure 2: Real implementation of a CC-10 controller, aMOXA server (left), and an ion pump controller (MPCqcontroller) (right).

Hardware – Real Implementation
A prototype of KAGRA vacuum monitoring system wasdeveloped. The real implementation is shown in Fig. 2 andFig. 3.
As in Fig. 2, the CC-10 controller is connected to theMOXA server by a RS485 cable, then connected to the
KAGRA local network. About the ion pump controller(MPCq controller), we tested the communication between
the controller and IOC with a MOXA server (throughRS485) or without MOXA server (through network), bothwere successful. We finally decided to connect the controller to the KAGRA local network directly.
Figure 3 shows a PLC controller, a control box, and a
micro-server (Saba-taro server). The PLC controller includes a D-in module, a D-out module, an ADC module,

Figure 3: Real implementation of a PLC controller, a micro-server, and a control box in KAGRA.

- 781 -Proceedings of the 19th Annual Meeting of Particle Accelerator Society of Japan
October 18 - 21, 2022, Online (Kyushu University)

PASJ2022 THP027

FUTURE PLAN

System Test in KAGRAIn February 2022, the prototype system was installed andtested in the KAGRA tunnel. Firstly, we opened and closed
the gate valves. Figure 4 shows the GUI of system, monitoring changes in the gate valves status (Open/Close) andpressure values. Secondly, remote monitoring of pump status (On/Off/Fault of a roots pump and a TMP) was confirmed. The “ON” indications are found in Fig. 4. The remote monitoring of an ion pump (by a MPCq controller)
was also confirmed in May 2022.
These results show that the remote monitoring of all thevacuum devices in real time has been achieved successfully.

At present, the prototype system realizes the monitoringof 2 gate valves, 3 types of pumps, and 1 gauge. The wholeof the vacuum system in KAGRA is shown in Fig. 5. The
prototype system covers only one of forty points.
In the fiscal year 2022, we would like to extend the prototype, and install a greater number of monitoring points
before the start of “O4”.

CONCLUSION
The prototype of KAGRA vacuum monitoring system
was developed and demonstrated toward “O4”. The prototype system is an EPICS-based system. It consists of a micro-server, a MOXA server, and a PLC controller. In February, 2022, the remote monitoring of 2 valves(Open/Close), 3 types of pumps (Run/Fault/Stop), and 1gauge (pressure in Torr) have been realized in KAGRA
successfully. In the fiscal year 2022, we would like to install a greater number of monitoring points before “O4”.

ACKNOWLEDGEMENTS

Figure 4: The upper picture shows the GUI of the prototype
system. The lower picture shows the pressure change
caused by the opening gate valves. The trend graph is by
an EPICS tool, StripTool.

We express our best thanks to J-PARC MR staff members and company (KIS) members for their encouragement
and suggestions during system development.
Special thanks go to Mr. Yoshihiro Sato for cablings ofserial lines for ion pumps and gauges.

REFERENCES[1] KAGRA introduction;

https://gwcenter.icrr.u-tokyo.ac.jp/en/[2] Collaboration KAGRA, “Performance of the KAGRA detector during the first joint observation with GEO 600 (O3GK)”,
Progress of Theoretical and Experimental Physics, 2022;
ptac093; https://doi.org/10.1093/ptep/ptac093[3] O. Miyakawa, “Realtime control for KAGRA covered by EPICS”, EPICS collaboration meeting, May 2017, Osaka, Japan.
[4] N. Kamikubota et al., “J-PARC control toward future reliableoperation”, in Proc. ICALEPCS2011, Grenoble, France, 2011,
pp. 378-381.
[5] S. Yamada, “Deployment of a tiny fan-less server as IOC in
J-PARC main ring”, Proceedings of the 13th Annual Meetingof Particle Accelerator Society of Japan, August 8-10, 2016,
Chiba, Japan. pp. 634-636.
[6] StreamDevice;
http://epics.web.psi.ch/software/streamdevice/[7] J. Odagiri et al., “EPICS device/driver support modules for
network-based
intelligentcontroller”,
inProc.
ICALEPCS2003, Gyeongju, Korea, 2003, pp. 494-496.
[8] netDev; https://github.com/shuei/netDev

Figure 5: Figure of vacuum system for KAGRA.

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