The U100 undulator

To produce infrared light up to 280 μm a hybrid undulator (U100) has been installed at the radiation source ELBE. It consists of 38 periods each 10 cm long with Sm2Co17 magnets and soft-iron poles.

The undulator gap can be varied from 24 mm to 150 mm by means of a girder system. The resulting undulator parameter varies from 2.7 to 0.3. To let pass radiation longer than 40 μm through the undulator gap a partial waveguide was installed. It spans from the upstream undulator entrance to the downstream mirror.


The main parameters of the undulator U100

Perod length

10 cm

Number of periods


Minimum gap

24 mm

Maximum undulator parameter Krms


Krms(gap) U100

On-axis magnet field amplitude Bu (left axis) and rms undulator parameter Krms (right axis) as a function of the undulator gap g.