Development of stretched wire system for magnetic field measurement of magnets for Siam Photon Source II

A stretched wire measurement system was developed for magnetic field measurement of magnet prototype for Siam Photon Source II. It is used for magnetic field integral measurement for characterization of multipole field errors, magnet centering and fiducialization of multipole magnets. The wire trajectory across magnet aperture can be either linear or circular. The maximum wire movement is ±100 mm in both horizontal and vertical directions with the positioning accuracy of ±2 µm. The system is built on a 3.2-m granite support which allows the maximum magnet length of 2.2 m and magnet weight of 2,500 kg to be measured. Effects of wire tension, scan region, pause time between measurements, wire movement speed, number of repeated measurements and number of data points have been studied. With the optimized measurement parameters, the repeatability of 3E-4 or better can be achieved for the normalized multipole components measured using the circular scan.