THE PRESENT STATUS OF THE CONTROL SYSTEM FOR
A STRETCHER-BOOSTER RING AT TOHOKU UNIVERSITY
M. Mutoh, M. Nanao, Y. Shibasaki, O. Konno
M. Oyamada and T. Tamae
Laboratory of Nuclear Science, Graduate School of Science, Tohoku University
1-2-1 Mikamine, Taihaku-ku, Sendai 982-0826, Japan
I. AbeKEK, High Energy Accelerator Research Organization
Oho Tsukuba-shi, Ibaraki 305-0801, Japan

Abstract
A stretcher-booster ring (STB) was constructed in theautumn of 1997 and has been commissioned. The main
operation modes of the STB, a stretcher-ring mode andbooster-ring mode, have achieved their design
performance so far. The STB control system, based on
personal computers (PCs), was developed to perform a
multi-mode operation and has functioned successfully.
The PCs are run as a client/server system using WindowsNT. The server PC plays the role of database server, andabout eleven client PCs have different particularfunctions. All of the PCs are interconnected with a
100Base-TX/FX Ethernet. Some types of commerciallyavailable software are employed to reduce thedevelopment and maintenance loads, in particular
LabVIEW, used as a graphical user interface on theoperator consoles, has contributed to the construction of
the software system in a short period of time. In thispaper, we introduce the STB control system and reporton its current status.

modes, which include the stretcher-ring, the storage-ringand the booster-ring, and because the beam channel aswell as the beam energy and current must be changed
frequently in a multipurpose accelerator such as this.
Moreover, since our accelerator is operated by people
who are not acquainted with accelerator structure, thecontrol system had to be developed which incorporated
techniques for extracting beam parameters from beam
monitor signals, programs for beam orbit simulation andcorrection, and abstractions to hide the accelerator
components and configuration from the operator. Inaddition, it is generally necessary to provide, in a shortperiod of time, good reproductions of operation values
and of the statuses of accelerator devices. The STB
control system [2] has been designed and constructed tosatisfy these requirements.
The main operation modes of the STB, the stretcherring mode and booster-ring mode, have so far performed
as they were designed to, and the STB control system has
functioned successfully.

2 HARDWARE CONSTRUCTION
1 INTRODUCTION
Coincidence experiments using continuous electron
beams have been commonly performed in the nuclear
physics field. Several kinds of continuous beam
accelerators, e.g., pulse stretchers, microtrons andrecirculating linacs, have been constructed throughout
the world for use in such experiments. The first pulsestretcher rind was constructed in 1981 at Tohoku
University and was subsequently used for coincidence
experiments. The construction of a new ring, known as
STB [1], was approved in 1995, and the STB wasconstructed in the autumn of 1997. The STB functions
not only as the stretcher-ring for supplying thecontinuous beam, but also as a storage-ring for nuclear
experiments and as a booster-ring, which accelerates thebeam up to 1.2GeV from 300MeV in order to inject it
into a proposed synchrotron-light facility. The operationof the STB is very complex due to its three operation

An outline of the STB control system is shown in Fig.
1. The control system consists of twelve PCs and eightprogrammable logical controllers (PLCs). The PCs play
particular roles, as follows:(1) a database server and a main control computer,(2) an operator's console installed in an accelerator
control room,(3) a video signal digitizer for beam screen monitors,(4) a beam signal processor for button-type position
monitors and wire-scan type profile monitors,(5) a wave form processor that observes signals fromthe pulsed operation devices,(6) a ramp-up pattern generator that provides reference
signals to the magnet power supplies during
booster-ring mode operation,(7) a gateway between the computer network and thePLC network,

(8) a WWW server for providing real-time informationon the accelerator operation to the Internet [3].
LabVIEW

Operator console

DLL
Net-libraryDB-libraryStored procedure

Database
Stored procedure
ODS

Device manager

Database server
Simulation andorbit-correction
programs(Fortran, C)

Device controller

PLC network
PLC

Figure 1: The control system architecture.

Figure 2: Software scheme of the control system.

The PCs run as a client/server system using WindowsNT. All of the PCs are interconnected with 100BaseTX/FX Ethernet.
The PLCs work as an interface between the accelerator
components and the control computer system. The PLCs
are from the OMRON CV1000 series. A PC used as agateway converts messages both on a control computer
network and a PLC network (Token bus, 2MHz) in orderto facilitate communication between the database and thePLCs. The gateway polls every PLC at 400ms intervals,
and transfers the collected operation data of theaccelerator devices to the database. We developed a PLC
driver library [4] running in Windows NT.
A ramp-up pattern generator supplies the reference
patterns to the magnets and the RF source so as toaccelerate the beam energy from 300MeV to 1.2GeV inthe booster-ring mode of operation. This generator iscomprised of a PC and a memory unit. The memory unit
consists of five memory modules having 128K word
memory, and a memory controller, all of which areconstructed as CAMAC modules. The PC calculates thepattern data in detail according to the outline patterndata of each magnet as entered at the operator console,and saves the data into each memory module. The
pattern data is read out sequentially at 100µs intervals.
The CAMAC crate controller and an interface card areused in Kinetic 3922 crate controller and 2927 interface
card for PC, and the driver library in Windows NT wasdeveloped in our laboratory using the DDK development
library (WinDK) supplied by Blue Water Systems.

3 SOFTWARE CONSTRUCTION
The block diagram of the control software is shown inFig. 2. The control system consists of three layers: ahuman-interface layer (namely, an operator console), acontrol layer (namely, the database), and a device layer(namely, the device controller).

3.1 Operator console
The PCs used for the operator's console have a graphic
accelerator to enhance their drawing speed, because fastdrawing and quick response are required of console
displays to ensure good performance as a man-machineinterface. The display windows on the consoles were
produced using LabVIEW. Using LabVIEW enable thesoftware development load to be reduced because
LabVIEW has various GUI components, for example,
meters, switches, slide-volumes, a wave-form charts, andso on, and has excellent functions such as multi-thread
correspondence, communication between distributed PCs
and so on. Fig. 3 shows a typical window, that used tocontrol magnet power supplies. An operator can adjust
the parameters of accelerator devices displayed on thescreens using the mice provided for the console PCs, andcan also control them using the four knobs provided on
the console desk so as to handle four parameterssimultaneously. LabVIEW is also used to display thecurrent or voltage waveforms of the power supplies underpulsed operation. The signals are selected by a coaxial
switch, and digitized by oscilloscopes. This data is thencollected by the PC located near the power supplies using

Figure 3: Typical control window.

flexibility of the control system. The
database improved our ability toadminister the control data and toincorporate application programs
into the system. The control database,MS-SQL Server, is installed in theWindows NT Server. Because thedatabase is a control manager, every
communication
betweentheoperation console and the PLC must
be executed through it. If the control
data were rewritten erroneously by amistake, much damage would becaused to the control system. The
data is maintained along with stored
procedures, which behave like amethodinobject-oriented
programming, and is hidden toprotect it from improper access. Allaccess to the database must be
executedthroughthestoredprocedures.

4 CONCLUSION
We could construct the compact control systemusing PCs, PLCs and commercially availablesoftware. The control system has performed
successfully in the STB test operation of both thestretcher-mode and booster-mode. The practicaloperations for the nuclear experiments begin soon,
but since the control system has plenty of room for
improvement if it is to be easily operated, we willcontinue to update the hardware and software
configurations.
The authors wish to thank Dr. M. Kawabata fordeveloping the CAMAC driver library.
Figure 4: Example of waveform display.
GPIB and LabVIEW, and transmitted to the operator's
consoles in TCP/IP. On the operation consoles, the waveforms are displayed on a window designed to look much
like the front view of an oscilloscope, as shown in Fig. 4.
The four channel data (8bits/dot, 500dots/channel) are
updated on the console screen about three times per
second.
We can control the accelerator components andobserve the signals from other PCs connected to thecontrol network from outside the control room. Thisconfiguration is very convenient for developing thecontrol program and maintaining the accelerator.

3.2 Database
In order to fulfill some of the requirements of multimode operation, we employed the database [5] as acontrol manager, and found that it enhanced theREFERENCES[1] T. Tamae et al., “1.2GeV STRETCHER-BOOSTER RINGPROJECT AT TOHOKU UNIVERSITY”, The XVI RCNPOSAKA International Symposium on Multi-GeV HighPerformance Accelerators and Related Technology, Osaka,
Japan 1997
[2] M. Mutoh et al., “A New Approach to Control System for
Medium-Scale Accelerators”, International Conference onAccelerator and Large Experimental Physics ControlSystems, Chicago 1995
[3] M. Mutoh et al, “A Real-time Observation System ofAccelerator Operation using Java”, PCaPAC99[4] M. Nanao et al., “Development of PLC Driver forAccelerator Control”, The 22nd Linear Accelerator
Meeting in Japan, Sendai, Japan 1997
[5] M. Mutoh et al., “Improvements in Database System forAccelerator Control”, International Conference onAccelerator and Large Experimental Physics ControlSystems, Beijing 1997