A stretch-wire system for accurate integrated magnetic field measurements in undulators

In order to characterize the undulators used for 3rd synchrotron radiation light source, a stretch-wire magnetic field integral measurement system for measuring the first and second magnetic field integral distributions and integrated multipole errors in undulators has been established. The main features of this system are its high speed and high precision of the measurement, without space limit. Preliminary results demonstrate that the system achieves a system measurement precision of 1.2 Gs·cm for the first integral and 150 Gs·cm2 for the second integral. The system is efficient enough to carry out the measurements of magnetic field integral in undulators. (authors)