Compound X-ray amorphous radiation-cooled filter based on free-standing thin films for synchrotron radiation facilities

A radiation-cooled X-ray amorphous filter based on thin films is proposed for use at 4th generation synchrotron radiation facilities‘ beamlines. This filter can be exploited under conditions of high thermal loads and high coherent photon flux fraction. In order to ensure X-ray amorphousness, it is proposed to use glassy carbon, metallic glasses, and multilayers with nano-sized periods as filter materials. Filtering is assumed to be carried out in stages: first, radiation in the low-energy range (up to $\sim$5 keV), and then, if necessary, in the medium-energy range (up to $\sim$15 keV) being suppressed. It is proposed to use a set of glassy carbon films as an absorber for primary filtering and a set of films containing elements with higher atomic numbers for additional filtering. The selection of filter film materials allows for consistent suppression of undulator harmonics when operating in the high-energy range (above 15 keV). Modeling of thermal loads and stationary temperature distribution has been carried out for glassy carbon films. The thickness of these radiation-cooled films is chosen in such a way that their maximum temperature in thermal equilibrium does not exceed the graphitization temperature.