The asymmetric hybrid wiggler at Orsay

A special multipole hybrid wiggler optimized to produce an intense flux of circularly polarized photons was designed and successfully tested at Orsay. The wiggler was installed on the Synchrotron Radiation Source Super-ACO (E=0.8 GeV) in March 1990. A high flux is produced in a broad energy range extending from the infrared 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 12 magnetic periods (λ=263 mm) made of neodymium iron boron permanent magnet blocks and of 2 families of iron poles (main pole and lateral poles). In each drift space small shimming SmCo₅ permanent magnets 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