Design And Implementation Of The Control System For CYCHU-10 Cyclotron

PET(Positron Emission Tomography) is deemed as the most advanced technique of nuclear medicine in detecting of incipient tumors which has been applied in many hospitals around the world. Low-energy cyclotron is the primary isotope generator which is designed for short-life isotopes production in PET system. At present, in our country, all of the cyclotrons for PET detectors in business depend on import. So it is significant to research and develop the compact low-energy cyclotron matching with PET system with our own independent intellectual property right.Control system is an important part of cyclotron which is directly related to the safety and stabilization of the system. Based on the analysis of structural characteristics and operation mode of the compact low-energy cyclotron CYCHU-10 as well as the properties and control requirements of each system, the overall structure of the distributed control system is established. Considering the high reliability requirements and complex working environment, SIEMENS S7-300 PLC is selected as the general controller. LabVIEW is applied to develop the host computer program because of its good human-computer interface, high programming efficiency and high flexibility.In this thesis, the control methods of Radio frequency(RF) power supply, magnet power and ion system are introduced in detail. For the specific requirements, the system configuration of RF system is described in this paper. The fundamental wave of Direct Digital Synthesis(DDS) is selected as the RF signal source output signal and power adjustment method is presented based on variable gain low power amplifier. The operating modes and process of RF power supply are introduced. The program development and monitoring interface under the LabVIEW environment are put forward. The data acquisition system for RF power source is presented based on NI PCI. Moreover, the experimental results and fit curve of the RF power supply is introduced. Basing on the theoretical analysis of isochronous cyclotron, the relation between magnet current and frequency is put forward, as well as the operation curve of the magnet current. The basic concepts and discharge principle of inner negative hydrogen penning ion source with cold cathode is introduced in this paper besides the control method of ion source power supply and gas feeding system.Finally, the actualization method of the other subsystems is discussed including the water cooling system, vacuum system, beam diagnosis and safety interlock system. Especially the structure and control parameters of water cooling and the extraction process of vacuum system. In addition, the graphical user interface(GUI) and the general control logic are developed to realize the configuration of the whole control system.