Undulator shimming

Fig. 1.: Magic Finger for compensation of integrated field integrals. The slits are filled with permanent magnets of appropriate size.

Fig. 2: Bench for local and integrated magnetic field measurements

Fig. 2: Bench for local and integrated magnetic field measurements: The system consists of a slide on air cushions on a 6 m long granite (maximum travel 5.5 m). A Hall probe is located on an extender reaching into the magnetic gap of the undulator. The position of the Hall probe is reproducible by better than 5 μm and is measured using a laser interferometer. The system is also used to verify the mechanical straightness of completely assembled. Additionally, a moving wire system is used to characterize the integrated multipoles with a high accuracy. It consists of two xyz positioning systems at either end of the undulator. A wire is stretched between them through the active volume of the undulator. The voltage induced in the wire is recorded. First and second field integrals are obtained as function of the transverse and vertical position inside the gap. The wire is also part of a pulsed wire set-up.