General Description

The first insertion device U46, installed in the upstream position of the low b straight section, is a 46mm period device with a magnetic field of 0.63T at 16.2 mm gap. At closed gap the fundamental is 1.60 keV and the deflection parameter is K=2.7 and it may be considered a wundulator. It produces a total power of 3032 W at 200mA. It is the insertion device of choice for monochromatic data collection on the energy range 8 - 12  keV and holes of the in-vaxuum undulator above 20 keV to 25 keV.

The most important device is a U17 single line undulator. Its magnets sit within the vacuum of the electron beam thus allowing to achieve much smaller magnet gap settings. The spectrum is dominated by a single tooth-shaped line with a sharp energy cut-off at 15.6 keV at 6.5mm gap followed by a broad second order and a considerable intensity at the peaked third order. The deflection parameter is 0.86 and total power of 400 W. It has been used for narrow band Laue diffraction  (MbCO). The narrow band width reduces the number of spots which facilitates the intensity integration procedure . This point is particularly important for crystals which diffract to high resolution.
As the device is still in the extended commisioning phase the outstanding gain in performance is still being explored.

ID poles min. gap Bmax(T) K Ef(keV) Ec(keV) Power (W/200mA) power density 
U46 71 16 mm 0.643 2.76 0.64 15.6 3116 66.1
U17  235 6.0 mm 0.544 0.86 14.8 13.2 2737 172



period [mm]
no of poles
Length [mm]
B1 [T]
B2 [T/mm]

critical energy and power production of U46 (42 kB)


period [mm]
no of poles
Length [mm]
B1 [T]
B2 [T/mm]

spectrum of U17 (183 kB)

The spectral intensity of the in-vacuum undulator U17 for two setting of the vertical acceptance pvg [mm]. The transmission of the beamline windows and the reflectivity of the toroidal mirror (Pt-coated @ 2.683 mrad) is also shown. A double-bounce silicon 111 monochromator is expected to produce 1.3 x 10^14 ph/s at the fundamental at 14.8 keV at a synchrotron current of 0.2 Ampere.

expectable peak intensities (127 kB)

The energy of the harmonics of the in-vacuum undulator U17 can be varied by changing the gap between the poles of the undulator.
The highest intensity is obtained at 6.0 mm gap. The next value is calculated for 7 mm etc. Note the holes in the energy range due to the low K of 0.86. The curve does not include losses in the beamline (windows and mirror reflectivity).