Design and Performance Measurement of Control System for Elliptically Polarized Undulators in Taiwan Photon Source

In phase I of the Taiwan Photon Source (TPS) project, three elliptically polarized undulators (two EPU48 and one EPU46) are installed in the TPS storage ring. The control system for these EPU48 and EPU46 is based on the EPICS architecture; all control functionality is coordinated by the CompactPCI EPICS IOC. The main control components include motors with an encoder for gap adjustment and phase moving, a trimming power supply for corrector magnets, temperature sensors for environmental monitoring of the insertion devices, and an interlock system (limit switches, tilt sensor, emergency button) for safety. The closed-loop control is essential for the gap and phase motion to avoid the effects of magnetic forces. All motors of the gaps must be synchronized to move without tilt. An interface for ID beamline users is included to assist with experiments, such as to control the ID gap or phase and experiments on the fly. The features and benefits of the EPU48 and EPU46 control systems are summarized in this paper.