Conceptual design of vertical undulator

A new undulator requiring no constraints in the horizontal beam direction is proposed for generating vertically polarized radiation. This undulator consists of two pairs of planar permanent magnet arrays above and below the electron orbit plane, and generates horizontal magnetic field on the electron orbit which induces vertically sinusoidal electron motion. The configuration of magnet blocks in each array is same as the conventional Halbach type undulator. This device generates 1.3 times higher horizontal peak magnetic field compared with new helical undulator proposed by Sasaki et. al. in vertical polarization mode. In addition, this device can also generate helical magnetic field for generating circularly polarized radiation by changing the relative position of magnet arrays (phasing). (author)