title: A novel insertion device for circularly polarized radiation.
abstract: A novel insertion device for circularly polarized radiation with a wide available energy range is proposed. It consists of two helical undulators with different period lengths. From an analysis made on the radiation, higher harmonics are found to be contained in the radiation, unlike the ordinary helical undulator. In addition, calculations show that a high degree of circular polarization is obtained for finite beam emittance.
authors.forename: T
authors.initials: T
authors.lastname: Tanaka
authors.forename: H
authors.initials: H
authors.lastname: Kitamura