A permanent-magnet undulator technology, capable of generating extremely homogeneous magnetic fields, has been developed
for the UCSB Free-Electron Lasers. It has, so far, been applied to the FIR-FEL, the
MM-FEL, and the 30 µm FEL.
These undulators are based on the planar Hybrid configuration and employ a
novel robotic adjustment procedure that results in three-dimensional control of
field homogeneity. This has considerably reduced the cost of fabrication and has resulted in three different undulators
with unprecedentedly high field accuracies.
[gif 253K][jpeg 60K]
The undulator and resonator during final assembly. The undulator adjustment mechanism is clearly visible as are recesseses in
the resonator's vacuum chamber wall for the pole tips. This permits sufficient wall thickness to support atmospheric pressure
while accomodating a 5 mm waveguide height in a 7 mm undulator gap.
showing how undulator parameters were optimized to achieve high field strength.
Additionally, the highest quality magnet material, available at that time, was chosen. [gif 15K]
Final undulator field measurement shows the accuracy achievable with the tuning technique