Development and Operation of a Pr2Fe14B Based Cryogenic Permanent Magnet Undulator for a High Spatial Resolution X-ray Beamline

摘要

Short period, high field undulators are used to produce hard X-rays onsynchrotron radiation based storage ring facilities of intermediate energy andenable short wavelength Free Electron Laser. Cryogenic permanent magnetundulators take benefit from improved magnetic properties of RE2Fe14B (RareEarth based magnets) at low temperatures for achieving short period, highmagnetic field and high coercivity. Using Pr2Fe14B instead of Nd2Fe14B, whichis generally employed for undulators, avoids the limitation caused by the SpinReorientation Transition phenomenon, and simplifies the cooling system byallowing the working temperature of the undulator to be directly at the liquidnitrogen one (77 K). We describe here the development of a full scale (2 m), 18mm period Pr2Fe14B cryogenic permanent magnet undulator (U18). The design,construction and optimization, as well as magnetic measurements and shimming atlow temperature are presented. The commissioning and operation of the undulatorwith the electron beam and spectrum measurement using the Nanoscopmium beamlineat SOLEIL are also reported.