Using metallic filters in APS undulator beamlines

Abstract

Metallic filters are needed by APS users in their beamlines. Two general areas of use for the white-beam metallic filters are: (1) to attenuate the x-ray beam to reduce the thermal load during routine operations and (2) to attenuate the x-ray beam during alignment and for special testing of optics at low power. Metallic filters are important for users who will be working primarily in the high energy x-ray range because unwanted lower energy photons are absorbed through the metallic filters. Notwithstanding their high thermal conductivity, the metals, in general, absorb x-rays significantly near surface layers and hence can attain very large temperatures causing structural deformations and/or damage. Thermomechanical behavior and failure prediction need to be done carefully. In this paper, particulars of metallic filters are discussed and generalized analytical solutions are offered to help users of metallic filters determine their applicability for x-ray beamlines