In-Vacuum Undulator Installed
Commisioning of the Hard X-ray Microfocus Beamline (BL15U1), which is the first in-vacuum undulator beamline at Shanghai Synchrotron Radiation Facility (SSRF), began at 19:00pm on February 6, 2009. The X-ray beam was observed immediately on the fluorescent screen and XBPM at beamline. At 21:30pm, a monochromatic beam at 5.4 keV (the third harmonic) was detected at the endstation, denoting the success of the first step commissioning.
In the following days, the harmonic spectrum of undulator light source was measured. Tests of the near K-edge absorption of copper foil and X-ray fluorescence for standard reference samples of trace elements, SRM610(500ppm)and RM614(1ppm), have been carried out.
As a light source equipment of this beam line, the undulator is the first in-vacuum type undulator developed in China. The design, assembly and shimming are carried out in the Shanghai Institute of Applied Physics, Chinese Academy of Sciences (CAS). The in-vacuum undulator is a complex equipment combined with many high techniques, including high quality magnet, ultra high vacuum, high precision mechanical driving and control, etc. This undulator has a hybrid type magnet arrangement with a period length of 25mm and a number of periods of 80. The minimum operation gap is 7mm and the maximum peak magnetic field is 0.95T. All the magnet blocks and poles, as well as the holders and girders are located inside of the vacuum chamber. Double motors driving system is adopted to adjust the gap in parallel mode and taper mode.
The development of the undulator was started at the beginning of March 2008 and completed in January 2009. It was installed in the storage ring on January 28. A brilliant quasi-monochromatic hard X-ray to eleventh harmonic was obtained in the detector at the end of the beam line. The commissioning results show that the phase error of the undulator is around 4 degrees.