Development of a 2 m Pr sub(2)Fe sub(14)B Cryogenic Permanent Magnet Undulator at SOLEIL

• Published in: Journal of physics. Conference series 2013-01, Vol.425, p.1-4
• Main Authors: Benabderrahmane, C, Valleau, M, Berteaud, P, Tavakoli, K, Marlats, J L, Nagaoka, R, Bechu, N, Zerbib, D, Brunelle, P, Chapuis, L, Dalle, D, Herbeaux, C, Lestrade, A, Louvet, M, Couprie, M E
• Format: Article
• Language: English
• Subjects: Adjustment; Cryogenic temperature; Magnetic fields; Magnetic measurement; Permanent magnets; Phase error; Praseodymium; Vacuum chambers
• ISSN: 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/425/3/032019

A 2 m long 18 mm period Cryogenic Permanent Magnet Undulator (CPMU) has been constructed at SOLEIL. Praseodymium was chosen instead of Neodymium magnetic material, because of the absence of the Spin Reorientation Transition phenomenon. The use of Pr sub(2)Fe sub(14)B with a remnence B sub(r) of 1.35 T at room temperature enables to increase the peak magnetic field at 5.5 mm minimum gap, from 1.04 T at room temperature to 1.15 T at a cryogenic temperature of 77 K. The magnetic field reaches 1.91 T at a gap of 3 mm in case of FELs applications. Different corrections were performed first at room temperature to adjust the phase error, the electron trajectory and to reduce the multipolar components. A dedicated magnetic measurement bench to check the magnetic performance of the undulator at low temperature has been designed and assembled inside the vacuum chamber. The results of the magnetic measurements at low temperature and at room temperature are compared. The CPMU has been installed and commissioned in the storage ring.