Feng, Y. Delor, J.T. Krzywinski, J. Montanez, P.A. Ortiz, E. Raubenheimer, T.O. Rowen, M. TUP056 photon FEL simulation radiation synchrotron 2015 2015-12 Future high repetition rate X-ray FELs such as the European XFEL and LCLS-II presents new challenges to photon diagnostics as well as essential beamline components. In addition to these devices having to sustain the high peak power of a single-pulse FEL radiation, they must also be capable of handling the enormous power density of tens to hundreds of watts over an area as small as 0.1 mm X mm. In this talk, I will discuss the potential impact of high power FEL operation on performance of a gas attenuator and the design challenges to beam intercepting components such as a collimator or stopper.