Fundamental Power Couplers for Superconducting Cavities

Fundamental power couplers (FPC’s) for superconducting cavities must meet very strict requirements to perform at high power levels (hundreds of kilowatts) and in a variety of conditions (CW, pulsed, travelling wave, standing wave) without adversely affecting the performance of the cavities they are powering. Producing good coupler designs and achieving operational performances in accelerator environments are challenging tasks that have traditionally involved large resources from many laboratories. The designs require state-of-the-art activities in RF, cryogenic and mechanical engineering, materials science, vacuum technology, and electromagnetic field modeling. Handling, assembly and conditioning procedures have been developed to achieve ever-increasing power levels and more reliable operation. In this paper, the technical issues associated with the design, construction, assembly, processing and operation of FPC’s will be reviewed, together with the progress in FPC activities in several laboratories during the past few years.