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TY - CONF AU - Börgermann, F.-J. AU - Brombacher, C. AU - Üstüner, K. ED - Petit-Jean-Genaz, Christine ED - Arduini, Gianluigi ED - Michel, Peter ED - Schaa, Volker RW TI - Properties, Options and Limitations of PrFeB-magnets for Cryogenic Undulators J2 - Proc. of IPAC2014, Dresden, Germany, June 15-20, 2014 C1 - Dresden, Germany T2 - International Particle Accelerator Conference T3 - 5 LA - english AB - The gap induction and thus the K-factor of permanent magnet undulators may be increased by cooling them to cryogenic temperatures. The use of NdFeB-magnets in cryogenic undulators, however, is limited to temperatures above 140 K due to the spin-reorientation transition (SRT) which leads to a reduction of the magnetization level. A further increase of the gap induction in undulators may be achieved by use of PrFeB-magnets at even lower temperatures, as this alloy does not show the SRT phenomenon. Although the effects are well known, up to now only a few undulator prototypes were built using this class of material since the coercivity of ternary PrFeB-magnets is not sufficient to minimize the risk of partial demagnetization when the undulator structure is kept at room temperature. This problem can be solved by applying actual technologies like grain-boundary diffusion in order to achieve coercivities exceeding 20 kOe at RT without sacrificing the high remanence Br of about 1.6 T at 77 K. We will provide actual data of the magnet performance achieved and show up the technological limitations in building PrFeB-based CPMU’s. PB - JACoW CP - Geneva, Switzerland SP - 1238 EP - 1240 KW - undulator KW - cryogenics KW - permanent-magnet KW - induction KW - polarization DA - 2014/07 PY - 2014 SN - 978-3-95450-132-8 DO - 10.18429/JACoW-IPAC2014-TUPRO085 UR - http://jacow.org/ipac2014/papers/tupro085.pdf ER -