Two new beamlines at the Advanced Photon Source (APS) require two or three in-line undulators, respectively, to achieve the high photon intensity needed. With the expectation of a future higher storage ring beam current, a new front end is being designed to handle a maximum total power of 21 kW and a maximum peak power density of 590 kW/mrad~2, which is about 3.8 times the heat load with current operation of a single undulator at 100 mA stored beam current. This new front end will allow the operation of two in-line 3.3-cm-period, 2.4-m-long undulators at k=2.76 with 180 mA, or alternatively, three in-line undulators at k=2.0 with 150 mA. In this paper, the overall front-end high-heat-load management plan is discussed and front-end layout and aperture design are presented. A new design concept is used in key components, such as photon shutters and fixed masks, to handle the high power density. The design, thermal analysis and fabrication of these components are presented.
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