Status of development of Cryogenic Permanent Magnet Undulator at TPS

Jui-Che Huang^1*, Chih-Sheng Yang¹, Ching-Kang Yang¹, Cheng-Hsing Chang¹, Ching-Shiang Hwang¹

¹Magnet group, National Synchrotron Radiation Research Center, HsinChu City, Taiwan

* Presenter:Jui-Che Huang, email:huang.juiche@nsrrc.org.tw

A cryogenic permanent magnet undulator is under construction at the Taiwan Photon Source to provide high brilliant X-rays. When PrFeB magnets are cooled to 77 K, a CPMU with a period length of 15 mm and a gap of 4 mm can generate an effective magnetic field of 1.30 T. The main goals of TPS CPMU developments are low-intrinsic-phase errors and high thermal stability against diverse heat loads. Low-intrinsic-phase errors can be obtained by force-compensation modules on the out-of-vacuum girders in a four-support-point configuration. Furthermore, adjustments of the spring settings can lead to even lower undulator phase errors. Two cryo-coolers, each with a cooling capacity of 200W at 80 K, allow a high beam-induced heat load with external heat transfer of up to a few hundred watts. An in-situ and vacuum compatible field measurement system has been developed to characterize the magnetic field at cryogenic temperatures and allowing corrections of gap errors due to temperature variations. In this presentation, the relevant technology and test results for the TPS-CPMU will be discussed including some CPMU observations associated with phase errors, magnetic field quality at cryogenic temperature.

Keywords: Undulator, Taiwan Photon Source