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 construct ion 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/mm(2) at the ent rance of the front end. To handle such an intensive heat load within the re stricted space, a new configuration for high heat load components has been introduced. The basic design concept is to deal with most of the power upst ream of the absorber used to block the X-ray beam for user entry into the o ptics hutch. A series of four masks, two fixed and two movable, was newly d esigned. The movable masks, one having an aperture of 1.5 mm in the horizon tal and the other an aperture of 1.5mm in the vertical, will handle about 2 0kW of power within the total region of about 3m. (C) 2001 Elsevier Science B.V. All rights reserved.