Development of Cryogenic Permanent Magnet Undulators at the Tps
Jui-Che Huang1*, Ching-Shiang Hwang1, Chih-Sheng,Yang1, Ching-Kang Yang1
1Magnet group, NSRRC, HsinChu City, Taiwan
* Presenter:Jui-Che Huang,
Cryogenic permanent magnet Undulator (CPMU) technology is under development at the Taiwan Photon Source (TPS) to provide high-brilliance x rays. A 2-m long PrFeB CPMU with a period length of 15 mm can generate a maximum effective magnetic field of 1.77 T at a gap of 3 mm when the magnets are cooled down to around 77 K. The main desired specifications for the small gap TPS CPMU are low-intrinsic-phase errors and high thermal budget to various heat loads. A force-compensation modulus with four-support-points on the mechanical frame and temperature stabilization system on the in-vacuum girder are expected to keep the intrinsic phase errors low. Cryo-coolers with a cooling capacity of 400W at 80 K allow external heat loads up to a few hundreds watts, e.g. during a small gap operation. An in-situ, high vacuum combatible field measurement system has been included in the CPMU developemnt in order to characterize the magnetic field at cryogenic temperatures and to correct gap errors, e.g. due to temperature variations. In this paper, the relevant factors and technological challenges for the TPS-CPMU will be discussed. Some results of the CPMU associated with magetnic field quality at cryogenic temerpature and vacuum performance will be presented as well.

Keywords: Undulator, Taiwan photon Source, Cryogenic system