Design of the front end for the very long in-vacuum X-ray undulator at SPring-8

The beamline for the very long in-vacuum X-ray undulator is under construction in BL19LXU at SPring-8. The front end for the BL19LXU will be subjected to a total power of 33 kW with a power density of 1.92 kW/mm2 at the entrance of the front end. To handle such an intensive heat load within the restricted space, a new configuration for high heat load components has been introduced. The basic design concept is to deal with most of the power upstream of the absorber used to block the X-ray beam for user entry into the optics hutch. A series of four masks, two fixed and two movable, was newly designed. The movable masks, one having an aperture of 1.5 mm in the horizontal and the other an aperture of 1.5 mm in the vertical, will handle about 20 kW of power within the total region of about 3 m.