The JLab Ampere-class cryomodule conceptual design
Rimmer RA., Ciovati G., Daly EF., Elliott T., Hicks WR., Henry J., Kneisel P., Manning S., Manus R., Preble J., Stirbet M., Smith K., Turlington L., Vogel L., Wang H., Wilson KM., Wu G.
For the next generation of compact high-power FELs a new cryomodule is required that is capable of accelerating up to Ampere levels of beam current. Challenges include strong HOM damping, high HOM power and high fundamental-mode power (in operating scenarios without full energy recovery). For efficient use of space a high real-estate gradient is desirable and for economic operation good fundamental-mode efficiency is important. The technology must also be robust and should be based on well-proven and reliable technologies. For Ampere-class levels of beam current both halo interception and beam break-up (BBU) are important considerations. These factors tend to drive the designs to lower frequencies where the apertures are larger and the transverse impedances are lower. To achieve these goals we propose to use a compact waveguide-damped multi-cell cavity packaged in an SNS-style cryomodule.