A PrFeB-based cryogenic permanent magnet undulator (CPMU) is under construction at the Taiwan Photon Source (TPS) to provide high brilliant X-rays. When magnets are cooled to 80 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 paper, 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.
Development of cryogenic permanent magnet undulators at NSRRC
Jui-Che Huang, Hideo Kitamura, Chih-Sheng Yang, Ching-Kang Yang, Shinsaku Mizumoto, Cheng-Hsing Chang, Cheng-Hsiang Chang, Ching-Shiang Hwang; Development of cryogenic permanent magnet undulators at NSRRC. AIP Conf. Proc. 15 January 2019; 2054 (1): 030022. https://doi.org/10.1063/1.5084585
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