Short-period compact undulator (sCCU19) construction report

Following the successful completion and testing of the sCCU-type undulator with 28mm period, we have designed, prototyped, constructed and bench tested another sCCU-type undulator with a much shorter 19mm-period magnetic structure. sCCU-type undulators are compact variable-gap devices with hydraulic-assist driver and innovative hybrid magnetic structure. The hydraulic system provides compensation of magnetic forces and ensures compactness of the design. Owing to innovative magnetic structure, these undulators demonstrate magnetic peak field ~15% stronger compared to conventional hybrid-structure PM undulators. The newly constructed undulator is 1.5 m long, 0.38m high, 0.21 m wide and weighs ~ 180 kg. Magnetic structure has 19 mm period and 6.5 mm minimum gap. The gap can be varied from 6.5mm to 80mm. At minimum (6.5mm) gap, the undulator demonstrated 0.87 T peak magnetic field. Magnetic field measurements indicated satisfactory uniformity of the field and acceptable field integrals through the entire gap range. High reliability of undulator mechanics and the control system was confirmed by extensive, varied and prolonged testing.