Amor Nadji

Development of cryogenic undulators with PrFeB magnets at SOLEIL

Short period high field undulators are of interest for X-ray brilliance enhancement in synchrotron radiation applications and for compact Free Electron Lasers. Cryogenic in-vacuum undulators [1] are one of the possible solutions. At SOLEIL, PrFeB magnets were directly chosen, even if still under development at that time. Indeed, they enable to avoid the spin transition reorientation phenomenon which occurs with NdFeB magnets [2] and the magnets can be cooled down directly at 77 K. The first selected grade CR53 from Hitachi presents a remanence of 1.35 T at 293 K and 1.57 T at 77 K, with a coercivity of 1355 kA/m at 293 K and 6000 kA/m at 77 K. A 2 m long cryogenic undulator of period 18 mm was first built in-house, with a specific Hall probe bench directly installed in the final vacuum chamber. This first cryogenic undulator has been in operation on the storage ring for 4 years [3]. A second U18 cryo-ready undulator using a slightly different magnet grade with a higher coercivity and modules with magnets ...

SOLEIL, un centre de recherche pluridisciplinaire

Installation de tres haute technologie, SOLEIL est a la fois une source de rayonnement d’une brillance exceptionnelle, une plateforme de service ouverte depuis 2008 a toutes les communautes scientifiques et industrielles, et un laboratoire de recherche a la pointe des techniques experimentales.

COMMISSIONING OF THE LASER BEAM TRANSPORT FOR THE FEMTO-SLICING PROJECT AT THE SYNCHROTRON SOLEIL

The aim of the Femto-Slicing project at SOLEIL is to generate 100 - 200 fs FWHM short X-ray pulses on two beamlines, CRISTAL and TEMPO, for pump-probe experiments in the spectral range of hard and soft X-rays. We note that this capability could be extended in the future to two or three more beamlines. Femtosecond lasers are currently in operation on TEMPO and CRISTAL beamlines, for pump-probe experiments on the ps time scale, enabling time resolved photo-emission and photo-diffraction studies, respectively. The Femto-Slicing project is based on the fs laser of the CRISTAL beamline, which can be adjusted to deliver 3 to 5 mJ pulses of 30 fs duration at 2.5 to 1 kHz, respectively. This laser beam is separated in three branches: one delivering about 2 mJ to the modulator wiggler and the other ones delivering the remaining energy to the experiments on the TEMPO and CRISTAL beamlines. This layout will yield natural synchronisation between Infra-Red (IR) laser pump and X-ray probe pulses, only affected by jitter and drift associated with beam transport. In this paper, we present the progress in the implementation and commissioning of the laser beam transport system and its characterization.

W164: A WIGGLER DEDICATED TO THE PUMA BEAMLINE AND THE FEMTOSLICING PROJECT AT SOLEIL

An out-vacuum wiggler, W164, was designed, built and installed on the SOLEIL storage ring with the double objective to produce high energy photons for the PUMA beamline (10 keV to 70 keV) and to be used as a modulator for the FEMTOSLICING project [1]. The insertion device requires simultaneously reaching high critical energy of photons (above 10 keV) and low resonant energy (1.55 eV). The wiggler is composed of 20 periods of 164.4 mm made of NdFeB magnets and Vanadium Permendur poles. The maximum total field reaches 1.85 T at the minimum gap and 1.66 T at the FEMTOSLICING operation gap. The size of the poles, the carriage and the girders were optimized to minimize the deformation resulting from the magnetic forces (8 tons at minimum gap).