<title>Experimental and analytical studies on fixed mask assembly for APS with enhanced cooling</title>

Abstract

The Advanced Photon Source (APS) to be constructed at Argonne National Laboratory (ANL) utilizes magnetic devices which generate X-ray beams with very intense heat flux levels. The Fixed Mask Assembly (FMA) is the first component to interact with the X-ray beam. Two sets of a pair of FMA channels vertically and horizontally disposed contain the beam rather than define it. They are subject to very large heat fluxes during containment. In current practice the FMA channels are made of heavy seamless copper have rectangular cross-sections and are cooled internally with water. Channels are set at grazing angles ranging from 1 to 6 degrees with respect to the beam depending on the type of insertion device. APS insertion devices will impose higher heat fluxes on FMAs. Therefore a need exists to improve the FMA engineering keeping in mind the current design criteria and philosophy of FMAs. A comparative investigation of the conventionally achievable heat transfer coefficient h" with water and the wall conductance of a heavy wall copper tube reveals that major resistance is on the coolant side. Therefore there exists a significant opportunity to improve heat transfer in the tubes by enhancement of the coolant side. To this end an experimentally and analytically based research program has been adopted at the APS for investigating enhanced cooling methods and techniques. Currently a variety of copper wool filled tubes as well as a