Speaker
Description
A superconducting (SC) 1.4 GHz (4th harmonic) cavity is being developed for bunch lengthening in the Advanced Photon Source Upgrade. The cavity will be excited by the average 200 mA, 15.3 nC max, and ~50 ps long electron beams with the repetition rate of 13 – 88 MHz. Proper damping of higher order modes (HOM) in this cavity is an integral part of the development. A pair of the graphite-direct-sintered silicon carbide (SiC) HOM absorbers located outside the cryomodule are being developed. The silicon carbide HOM absorber assemblies were constructed and measurements of damping efficiency of the HOMs integrated with the cavity assembly were performed at room temperature. In addition, the cavity fundamental couplers are equipped with a ‘mode converting’ antenna for extraction of HOMs through the couplers transmission lines. The RF simulations, development, fabrication features, and room temperature measurement results will be discussed in this talk.
