Three transitional cryomodules (SL21, FEL03, Renascence) have been constructed as part of an energy upgrade effort at Thomas Jefferson National Accelerator Facility (JLab). Each transitional cryomodule contains eight superconducting radio‐frequency (SRF) cavities. Within the vacuum vessel, waveguides transmit up to 13kW of RF power to the superconducting niobium cavities. The waveguides also provide the thermal transition between the room temperature ceramic RF window and the niobium fundamental power coupler (FPC), a 300K temperature gradient across ∼20cm! The thermal performance of the waveguides is determined in part by the placement of heat stations and bellows. The original 13kW waveguide design incorporated a single 60K heat station and two bellows resulting in a total heat load (static + dynamic) to the FPC of ∼3W per waveguide. To minimize this heat load and stabilize the FPC temperatures, a 2K superfluid helium heat station design was incorporated into the second transitional cryomodule, FEL03, installed in the JLab Free Electron Laser (FEL). The designed heat station is capable of removing up to 1.12W, with a bath temperature of 2.05K, while remaining sub‐lambda. This paper describes the design, analysis and testing of the heat station.

This content is only available via PDF.
You do not currently have access to this content.