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TY - CONF AU - Longhi, E.C. AU - Miller, A.G. AU - Monroe, C. AU - Rial, E.C.M. AU - Rose, A.J. AU - Schouten, J.C. AU - Thompson, C.W. AU - Thomson, A. AU - Williams, J.H. ED - Petit-Jean-Genaz, Christine ED - Arduini, Gianluigi ED - Michel, Peter ED - Schaa, Volker RW TI - A New Cooling System for Cryocooled Permanent Magnet Undulators at Diamond Light Source J2 - Proc. of IPAC2014, Dresden, Germany, June 15-20, 2014 C1 - Dresden, Germany T2 - International Particle Accelerator Conference T3 - 5 LA - english AB - Cryocooled permanent magnet undulators (CPMUs) using NdFeB magnets around 150K were first proposed by Hara*. These are cooled by using either GM cryocoolers or circulating sub-cooled liquid nitrogen. Due to the heat load from radiation and wakefield heating from the electron beam, temperature gradients can develop along the length of the magnet girders which could be as large as several degrees for the Diamond Light Source (DLS) storage ring operating parameters. Some grades of the magnetic material (NdxPr1-x)2Fe14B have remanence curves versus temperature which increase significantly for temperatures below 150K with peaks below 80K**. This means that the operating temperature of a CPMU using this material can be close to the boiling point of liquid nitrogen. The proposed cooling system for the new DLS CPMU is based on a thermosiphon allowing nitrogen to boil inside the cooling channels without a circulating pump. This has the advantage of absorbing large amounts (>250W) of heat with very small temperature gradients. We report here the results of a prototype magnet beam cooled with a thermosiphon producing a temperature gradient of less than 0.05K along a 2m beam at ~77K. PB - JACoW CP - Geneva, Switzerland SP - 2047 EP - 2049 KW - vacuum KW - undulator KW - operation KW - cryogenics KW - electron DA - 2014/07 PY - 2014 SN - 978-3-95450-132-8 DO - 10.18429/JACoW-IPAC2014-WEPRO047 UR - http://jacow.org/ipac2014/papers/wepro047.pdf ER -