Design of an actuator for the fast and high accuracy Wire Scanner

This paper presents the design of the actuator for the fast and high accuracy Wire Scanner system. The actuator consists of a rotary brush-less synchronous motor with the permanent magnet rotor installed inside of the vacuum chamber and the stator installed outside. Fork, permanent magnet rotor and two angular position sensors are mounted on the same axis and located inside the beam vacuum chamber. The system has to resist a bake-out temperature of 200°C and ionizing radiation up to tenths of kGy/years. The requirements imply a maximum angular speed of 210 rad.s^-1 an required acceleration of 20 000 rad.s^-1 and a angular position measurement accuracy of 5 arc seconds. The system must deal with extremely low vibration and low electromagnetic interference. A digital feedback controller will allow maximum flexibility for the loop parameters and feeds the 3 phases linear power driver. The performances of the presented design are investigated through simulations and experimental tests.