The first synchrotron radiation beamline using a 4-m-long undulator at the 12 GeV storage ring PETRA delivers hard x- ray photons usable up to 300 keV. In order to reduce the low energy photon flux and the related thermal load on the beamline optics, graphite, beryllium, aluminum, copper, and iron filters or windows are installed. With a planned upgrade of the undulator, a deflection parameter of K equals 2.59 will be reached. The total radiated power of the undulator will then reach (with closed gap) about 15 kW. The central power density will be about 107 W/mrad2. Therefore, the design of the filters and windows which interact directly with the white beam becomes a very challenging engineering problem. The heat transfer and thermal stress analyses of PETRA filters and windows are presented. Different filter or window thicknesses, sizes, at different deflection parameters of the undulator, are discussed. Improved filter or window designs are proposed.
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