HOM Absorber Design for eRHIC ERL Cavity Phase IIA Proposal

The Office of Nuclear Physics has begun development for a polarized electron-ion collider. A high current design is required to provide high luminosity. High power higher order modes develop within the superconducting radio frequency cavities. These modes must be absorbed to minimize their effects on the beam. To preserve the beam and its characteristics the cavities require higher order mode absorption. The core of a broadband absorber design allows for conforming to either a waveguide or beamline absorber. This core can be used to design an absorber for crab cavities. RF, Thermal and Structural Analysis were completed to show feasibility. The primary absorbing component and holder were joined to demonstrate the manufacturing process and provide excellent thermal contact. In Phase II we finalized the designs and built a waveguide and beamline prototype we were not able to test the prototypes. In Phase IIA we will develop a low weight waveguide prototype, set up and perform low power RF testing. Will use equipment presently at BNL with some modifications to perform high power absorption tests of the core assemblies. Future accelerators for treating potable water, waste water cleansing, medical waste cleansing, treating asphalt to improve wear, and other energy and environment needs can be addressed with high current accelerators. These accelerators will need absorbers to work efficiently.