A REVIEW OF THERMOMECHANICAL CONSIDERATIONS OF HIGH-TEMPERATURE MATERIALS FOR SYNCHROTRON APPLICATIONS

The third generation synchrotron facilities such as the 7-GeV Advanced Photon Source generate X-ray beams with very high heat load and heat flux levels. Certain front end and beamline components will be require d to sustain total heat loads of 3.8 to 15 kW and heat flux levels exc eeding 400 W/mm2 even during the first phase of this project. Grazing geometry and enhanced heat transfer techniques in the design of such c omponents reduce the heat flux levels below the 30 W/mm2 level, which is sustainable by the special copper materials routinely used in the c omponent design. Although the resulting maximum surface temperatures a re sustainable, structural stresses and fatigue issues remain importan t concerns. Cyclic thermal loads have a propensity to cause spallation and thermal striping. As such, the steady-state part of the problem i s much easier to understand and handle than the time-dependent part. E ase of bonding as well as ultrahigh vacuum and radiation compatibility are additional constraints on material selection for these components . The two copper materials, which are very commonly used in synchrotro n components, are the traditional oxygen-free high-conductivity copper (OFHC) and the newer dispersion-strengthened copper, Glidcop. New mat erials are also appearing in heat sinks or heat spreaders that are bon ded to the base copper in some fashion. These are either partially tra nsparent to X-rays and have engineered volumetric heating and/or are v ery thermally conductive to spread the thermal load in a preferred way . These materials are reviewed critically for high-heat-load or high-h eat-flux applications in synchrotrons.