ANL, Argonne, USA
Purdue University, West Lafayette, Indiana, USA
The first prototype superconducting undulator (SCU0) was successfully installed and commissioned at the Advanced Photon Source (APS) and is delivering photons for user science. All the requirements before operating the SCU0 in the storage ring were satisfied during a short but detailed beam commissioning. The cryogenic system performed very well in the presence of the beam. The total beam-induced heat load on the SCU0 agreed well with the predictions, and the SCU0 is protected from excessive heat loads through a combination of orbit control and SCU0 alignment. When powered, the field integral measured with the beam agreed well with the magnet measurements. An induced quench caused very little beam motion, and did not cause loss of the beam. The device was found to quench during unintentional beam dumps, but quench recovery is transparent to storage ring operation. There were no beam chamber vacuum pressure issues and no negative effect observed on the beam. Finally, the SCU0 was operated well beyond its design requirements, and no significant issues were identified. The beam commissioning results are described in this paper.
ANL, Argonne, USA
Development of a new fast-switching Electromagnetic Variably Polarizing Undulator (EMVPU) is underway at the Advanced Photon Source (APS). The EMVPU can produce x-rays with left- and right-handed circular polarizations and horizontal and vertical linear polarizations in the energy range 400-2000 eV. The undulator will be able to switch between left- and right-handed circular polarization at 10 Hz, fast enough to allow for magnetic circular dichroism studies that rely on lock-in amplifier techniques. The handedness switch will be accomplished by switching only the vertical component of the field while the horizontal component stays constant. Details of the EMVPU and its initial experimental test models are presented.
ANL, Argonne, USA
An electromagnetic variably polarizing quasi-periodic undulator was installed in the Advanced Photon Source (APS) storage ring in April 2012 and has been successfully commissioned with stored beam. This device is identified as the Intermediate Energy X-ray (IEX) undulator. The IEX undulator takes its name from the IEX beamline where it is installed. The IEX undulator is able to produce a variety of polarizations: linear vertical, linear horizontal, and right- or left-handed elliptical or circular. Ten pairs of poles, distributed quasi-periodically along the undulator length, are powered separately, allowing the field strength of the quasi-periodic poles to be adjusted. This adjustability allows the user to seek a balance between the suppression of the higher harmonics and the loss of flux in the fundamental that best suits the measurement being made. The IEX undulator has a 12.5-cm period and can achieve photon energies as low as 250 eV in horizontal polarization and 440 eV in vertical polarization. A description of the IEX undulator will be presented.