Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 47 (2014)

PALIS laser interlock system for human and machine protection
T. Sonoda,∗1 I. Katayama,∗1 M. Wada,∗1 H. Iimura,∗2 F. Arai,∗3 and Y. Itou∗3
A laser interlock system has been developed to facilitate safe operation and machine protection in the newlaser system for PArasitic slow RI-beam production byLaser Ion Source (PALIS)1) .
Fig. 1 shows the overview of the interlock system forthe current PALIS laser setups. There are many items
pertaining to laser operation, for example dye circulator, chiller, air compressor, laser beam shutter, power
meter, wave meter, and so on. These often depend oneach other. If some interruption in dye ﬂow occurs during the irradiation of strong pump laser beam, the dye
cell and dye itself are damaged almost immediately.
Further, if cooling water stops or leaks, those devices
that require refrigeration stop functioning. These accidents are dangerous and can potentially start a ﬁreor cause fatal damage to laser devices. The irradiationof laser beams direct on to the human body, especiallyon to the eyes must be avoided. Therefore, some safety
devices like a beam shutter or door interlock, are necessary. Additionally, a monitoring system is essential toestablish a robust system and to reduce the frequencyof operator interventions for reading laser beam power,
laser beam position, and wavemeter.
In this circumstance, one needs to build an automated system using a programmable logic controller
for operating all devices remotely. We adopted a National Instruments (NI) Compact RIO system thatare referred from ISOLDE RILIS2) . NI CompactRIO
incorporates a real-time processor and reconﬁgurable
FPGA. The hot-swappable industrial I/O modules
can directly connect to sensors and actuators. CompactRIO embedded systems are developed using highproductivity LabVIEW graphical programming tools
for rapid development.
The sensor devices for dye circulation are necessary
to monitor the dye ﬂow at all times. However, the dyesolution is often composed of volatile liquid, and theinterconnection of sensor surface on the liquid ﬂow is
not adequate. Here, we use two types of sensors on
an experimental basis. One is a vibration sensor thatcan detect a small oscillation of the ﬂow tube synchronized with a circulator’s pumping action. The other isan ultrasonic sensor that evaluates the echo of high frequency sound waves received back by the sensor. If anysensor detects an interruption in dye ﬂow, the beam
shutter immediately acts to stop the pump laser beam.
In addition to these sensors, alcohol sensors monitor adye leak. Several sensors are used for cooling water
to detect a leak and to monitor the dye temperature
∗1
∗2
∗3

RIKEN Nishina CenterNuclear science and engineering directorate, Japan Atomic
Energy Agency
Department of Physics, Tsukuba university- 211 -stability. The laser power meters and beam shutters
are coupled with air cylinders. Therefore, the air pressure is also monitored by a pressure sensor. The door
interlock system for laser beams was prepared in theBigRIPS room. The laser beams cannot be sent to theBigRIPS room unless any door in the BigRIPS room
is closed.

Fig. 1. The overview of the interlock system with interactive equipments for current PALIS laser experiment.

The laser interlock system for PALIS experiment isbeing developed. This system is motivated not only forhuman and machine protection but also for facilitating
an eﬃcient and robust experimental environment. By
eﬀective utilization of these system, the oﬀ-line andon-line commissioning test for PALIS will be started
from April 2014.
References
1) T. Sonoda et al.: AIP Conf. Proc. 1104 132 (2009).
2) Bruce Marsh, presentation slides in EMIS2012.