CIRCE beamline has a variable angle plane grating monochromator. A plane mirror and three diffraction gratings are used to cover the full energy range of 100 to 2000 eV. After the grating chamber, there are two toroidal mirrors which focus the beam onto the exit slit of the PEEM or NAPP branch. The energy resolution of the monochromator is around 8000 at an exit slit of 20 um and Cff = 2.25.

Source

The source for the Circe beamline is a Pure Permanent Magnet APPLE II helical undulator, inserted in the center of the 9th medium straight section of the ALBA storage ring. This device is capable of delivering linearly polarized light in any direction, as well as circularly-polarized light (left- or right-handed).