HALL-PROBE BENCH FOR CRYOGENIC IN-VACUUM-UNDULATORS

The Helmholtz-Zentrum Berlin (HZB) builds a 2m long in-vacuum Hall-probe measuring bench for the characterization of several in-vacuum cryogenic undulators currently under development. Accurate local magnetic measurements need a positioning control of about 5 μm. Fabrication tolerances and potentially strong temperature gradients require an active correction of the Hall probe movement along a straight line. The HZBbench employs a system of laser interferometers and position sensitive detectors, which are used in a feed-back loop for the Hall probe position and orientation.