Development of a prfeb cryogenic undulator at soleil

A cryogenic permanent magnet undulator (CPMU) is under development at SOLEIL in order to reach larger magnetic field and to produce higher brilliance in the hard X rays domain. Lowering the temperature of permanent magnets increases the magnetic produced field by 25%. Different grades of permanent magnets (NdFeB [1] and PrFeB) have been characterised. Magnetic measurements on a four period Cryogenic Test Bench (CTB) are compared to the characterisation of single magnet. Thermal characterisation has also been carried out. The design of the CPMU is under progress, the choice of PrFeB magnets simplifies the cooling system of the in vacuum girders. The design of a magnetic measurement bench based on a Hall probe and a stretched wire to perform low temperature measurement is almost finished.