ANL Advanced Photon Source crotch absorber design

The ANL 7 GeV Advanced Photon Source storage ring crotch absorber will be subjected to a very high photon loading power density, approximately 750 w/mm/sup 2/ at normal incidence. To accommodate this high heat load, two designs are studied: a V-type compound angle absorber and a horizontally rotated plate absorber. For both model, thermal and structural analyses have been carried out using 3 D finite-element analysis. The analysis indicates that the V-type compound angle absorber controlled the peak temperatures effectively within the given geometric constraints. Test samples made of GlidCop Al 15 (alumina dispersion strengthened copper) were evaluated with an electron beam welder. The predicted and measured temperature were in reasonable agreement. The overall absorber design includes a perforated screen in the positron beam area of the storage ring vacuum chamber to reduce RF impedance and to provide pumping access for the high local gas load.< >