Thermal Design of Synchrotron Radiation Exit Ports at CESR

CESR, running at the maximum design parameters (8 GeV, 100 ma), produces 177 watts/mrad of synchrotron radiation at the exit ports for CHESS (Cornell High Energy Synchrotron Source). Due to the low angle of incidence, this corresponds to a linear heat loading of 55 watts/cm at the normal vacuum chamber wall. At the exit line crotch, radiation striking at normal incidence results in an average linear load of 885 watts/cm. For a beam height of 0.12 mm this translates to a power density of 740 watts/mm2. We present a design for a crotch which can effectively dissipate this high power density and will be compatible with the ultra-high vacuum system of CESR. The structure is a composite of a beryllium heat diffuser and an axially cooled copper cylinder. At 8 GeV and 100 ma we anticipate no component temperatures higher than 330°C.