Background

2

As one of the most important equipment in free-electron lasers (FEL)

undulator system is as long as tens meters or even hundreds meters. Due to the industrial technical constraints of the undulator manufacture

undulator system has to be segmented by 5-m length. In order to ensure that the phase of the radiation field between two adjacent undulators is matched with each other

conventionally

phase shifter components are inserted between the adjacent undulators.

Purpose

2

This study aims to minimize the integral field error of the phase shifter for undulator linkage.

Methods

2

Based on the factor that the nonlinearity of pure permanent magnet can be ignored

the first order integral term of magnet field is derivated. By shimming the height and tilt angle of vertically magnetization block in the phase shifter

its integral error can be reduced. Finally

a two-dimensional high-precision Hall probe is used in the experiment to measure the integral error of the phase shifter in different magnetic gaps.

Results

2

After field correction

the integral error of the phase shifter is less than 20 Gs·cm both in the center line for all gaps and horizontal position x less than 2 mm at the minimum gap.

Conclusion

2

This method has been applied for all the 6 phase shifters that satisfy engineering design requirements in Shanghai soft X-ray free electron laser (SXFEL).