JASRI, Koto 1-1-1, Sayo, Hyogo 679-5198, Japan.
RIKEN SPring-8 Center, Koto 1-1-1, Sayo, Hyogo 679-5148, Japan.
Sci Rep. 2016 Nov 29;6:37937. doi: 10.1038/srep37937.
We report an unexpectedly large flux loss observed in permanent magnets in one of the undulators operated in SACLA, the x-ray free electron laser facility in Japan. Characterizations of individual magnets extracted from the relevant undulator have revealed that the flux loss was caused by a homogeneous magnetization reversal extending over a wide area, but not by demagnetization of individual magnets damaged by radiation. We show that the estimated flux-loss rate is much higher than what is reported in previous papers, and its distribution is much more localized to the upstream side. Results of numerical and experimental studies carried out to validate the magnetization reversal and quantify the flux loss are presented, together with possible countermeasures against rapid degradation of the undulator performance.
我们报告了在日本 SACLA 自由电子 X 射线激光装置运行的一个波荡器中观察到的永磁体中异常大的通量损耗。从相关波荡器中提取的单个磁铁的特性表明，通量损耗是由大面积的均匀磁化反转引起的，而不是由单个磁铁因辐射而损坏的退磁引起的。我们表明，估计的通量损耗率远高于以前文献中的报道，并且其分布更集中在上游侧。为验证磁化反转和量化通量损耗而进行的数值和实验研究的结果，以及针对波荡器性能快速劣化的可能对策一起呈现。
