The 22-Pole Superconducting 7-Tesla Wiggler for the DELTA Storage Ring

A superconducting wiggler with a magnetic field of 7 T is installed as an insertion device for three X-ray beamlines with photon energies of more than 30 keV used at the Dortmund Electron Accelerator (DELTA, Germany), a source of 1.5 GeV synchrotron radiation. Each of the two side beamlines is separated from the central one by 15 mrad and all three beamlines use a horizontal aperture of 5 mrad. To meet these requirements, the insertion device must have a period of 127 mm and a magnetic field of 7 T for the vertical aperture of a beam vacuum chamber 10 mm long and a flange-to-flange distance of 2.2 m. A superconducting 22-pole wiggler with a field of 7 T and a period of 127 mm operating in the zero boil-off mode is described. The concept and main approaches to designing the magnetic and the cryogenic systems are presented, along with the main parameters and results from testing the new 7-tesla superconducting wiggler for the DELTA storage ring.