IEEE TRANSACTIONS ON NLJCLMR SCIENCE, VOL. zyxwv 41, NO. 1, FEBRUARY 1994 188 zyxwvutsrqponm Operational Experience with the Control System of the LNS Superconducting Cyclotron. G. Cuttone, A. Rovelli, A. Amato, S. Pulvirenti INFN, Laboratorio Naeionale del Sud, V.le A.Doria ang. V. S. Sofia, 95123 Catania, Italy and D. Giove INFN, Laboratorio Acceleratori e Superconduttivita’ Applicata, V. F.lli Cervi 201 20090 Segrate (MI), Italy zyxwvu Ab~tract A Superconducting Cyclotron is now under development at LNS-Catania zyxwvutsr as a part of a heavy ion-facility. The fea- tures of the distributed control system of this accelerator and the experiences gained during its functioning will be reported together with its future improvements. I. INTRODUCTION A heavy-ion facility of the Istituto Narionale di Fisica Nu- cleare (INFN) is planned at the Laboratorio Nazionale del Sud (LNS) in Catania. It is based on a 15 MV MP-Tandem injecting radially into a Superconducting Cyclotron (SC) K=800 as booster. The facility will provide a large variety of heavy ions in a wide energy range (up to 100 Mev/amu for light ions and up to 20 Mev/amu for uranium). The Tandem has been operating since 1984 and actually works at the maximum voltage with no troubles [l]. The SC, designed at the University of Milan, after the first mag- netic measurements carried out at the Laboratorio Accel- eratori e Superconduttivita’ Applicata (LASA) in Milan, was moved in 1990 to the LNS for the final commission- ing [2]. Presently the final magnetic measurements with the cyclotron assembled in its final configuration are in progress. All the subsystems of the accelerator have been mounted and tested separately in the machine. The first Tandem beam injected in the SC is expected at the begin- ning of next year. The cyclotron and all the related beam transfer lines are totally computer controlled. The control system design started together with the machine construction and was a fundamental development tool during its main stages. In the construction stage the control system was an auxiliary tool for the development and test of each single apparatus; user friendly operations, reliability, possibility of working in a stand-alone mode and easy access to host comput- ers for printing, plotting and recording were the major re- quirements. During the commissioning stage it has become both a complex monitoring system with enhanced display capabilities and a flexible actuator able to operate on each device by means of open-loop commands. Finally in the normal operation stage, when the experience on the accel- erator complex is valuable, the control system will have to guarantee a functioning ”quite automatic” and beam parameters optimization. According to this scheme it is important to design a control system with a hardware and software architecture based on industrial or de-facto stan- dards to minimize the economic and manpower investment. 11. SYSTEM OVERVIEW The control system plays a central role in the operation of an accelerator and represents one of the major items in the budget. The architecture has to guarantee flexibility and modularity to allow any sort of modifications during its lifetime and an easy maintenance has to be carried out without any interference with the accelerator operations. A distributed system represents an ideal answer to these demands and may be easily implemented using commercial standard products. The main features of our distributed control system are the following: -the capability of driving the accelerator and the beam transfer lines toward a predefined state and maintaining them stable by means of operators’ actions; -a central operator desk (console) with enhanced graphic capabilities to allow easy and flexible man-machine inter- actions for controlling, monitoring and actuating each ac- celerator parameter; -a local control of each subsystem for servicing and trou- bleshooting. The SC control system is developed according to a three level architecture (see fig. 1). The intelligence has been distributed following a functional scheme (i.e. similar equipment or a complete machine subsystem is under the control of a single computing unit) both for the compact size of the SC and for the limited dimensions of our lab- oratory. At the field level, programmable microcontroller based boards interface directly each device implementing commands and data acquisition procedures. These intel- ligent boards are interconnected to the local station by means of a high speed serial bus. This station, repre- senting the process level, coordinates the functioning of an accelerator subsystem or of the beam transfer lines and guarantees the communication with the central console. The local stations and the operator console are intercon- nected by means of a local area network. The presentation level is implemented as a set of graphic workstations for the man-machine interaction. 0018-9499/94$04.00 zyxwvuts 0 1994 IEEE