THE ASYMMETRIC HYBRID WIGGLER AT ORSAY

A special Multipole Hybrid Wiggler optimized to produce an intense flux of circularly polarized photons has been designed and successfully tested at Orsay. The wiggler has been installed on the Synchrotron Radiation Source Super-ACO (E = 0.8 GeV) on March 1990. A high flux is produced in a broad energy range extending from the Infra-Red domain to the X-ray region (4 keV). The asymmetric magnetic induction is obtained by inserting drift spaces between the periods. The structure consists of twelve magnetic periods (lambda = 263 mm) made of Neodymium Iron Boron permanent magnet blocks (remanent field Br = 1.15 T) and of 2 families of iron poles (main pole and lateral poles). In each drift space small shimming SmCo5 permanent magnets (Br = 0.9 T) are introduced to cancel the residual field integral. The peak field achieved in a 34 mm gap is 1.05 T. The design, the construction, the magnetic measurements and some characteristics of the light source are described below. Nancy and Orsay laboratories were involved both for the project and the funding. In addition, laboratories of "Region de l'Est" of France and Mineralogie-Cristallographie, Paris are involved in part of the scientific program using the wiggler beam.