Status of ERL superconducting spoke cavity fabrication

We are developing laser Compton scattering (LCS) X-ray and gamma-ray sources combined with an energy-recovery linac (ERL) and a laser. The LCS X/γ-ray source is expected for application of non-destructive assay system of nuclear materials, analysis of nano-structure, drug development, medical diagnostics and so on. We have launched a 5-year research program to develop superconducting spoke cavity for LCS photon sources. Spoke cavities have many advantages such as shortening the distance between cavities, small frequency detune due to micro-phonics and easy adjustment of field distribution for strong cell coupling. We have almost finished cavity shape optimization and been making a study of mold design and mechanical design to fabricate the niobium one-spoke cavity. (author)