Pulsed-wire system for undulator measurement

Purpose More undulators are required of HEPS in future. The efficiency of traditional Hall-probe measurement method is relatively low, which is difficult to meet the measurement needs of large quantities of undulators. In order to improve debugging efficiency, the pulsed-wire method is required further improvement. Methods A pulsed-wire method is an effective method to achieve magnetic field distribution through narrow aperture of undulator. The pulsed-wire method works by sending a square current pulse through the wire, which will induce an interaction with the magnetic field due to the Lorentz force. This force causes the wire to be displaced, and this displacement travels along the wire in both directions as an acoustic wave. Measurement of the displacement in the wire over time using a motion detector yields the first or second integrals of the magnetic field. Results The accuracy and repeatability are the important requirements. The repeatability of the first field integral of the pulsed-wire system is better than 1 parts per thousand which meets the design requirements. Conclusions This paper illustrates the effectiveness of pulsed-wire system by test results. Through comparison, the accuracy of the system is proved. It provides a new important measurement system for undulators in future.