Abstract: A high-current, compact, conduction cooled superconducting radio-frequency cryomodule for particle accelerators. The cryomodule will accelerate an electron beam of average current up to 1 ampere in continuous wave (CW) mode or at high duty factor. The cryomodule consists of a single-cell superconducting radio-frequency cavity made of high-purity niobium, with an inner coating of Nb3Sn and an outer coating of pure copper. Conduction cooling is achieved by using multiple closed-cycle refrigerators. Power is fed into the cavity by two coaxial couplers. Damping of the high-order modes is achieved by a warm beam-pipe ferrite damper.

Abstract: A high-current, compact, conduction cooled superconducting radio-frequency cryomodule for particle accelerators. The cryomodule will accelerate an electron beam of average current up to 1 ampere in continuous wave (CW) mode or at high duty factor. The cryomodule consists of a single-cell superconducting radio-frequency cavity made of high-purity niobium, with an inner coating of Nb3Sn and an outer coating of pure copper. Conduction cooling is achieved by using multiple closed-cycle refrigerators. Power is fed into the cavity by two coaxial couplers. Damping of the high-order modes is achieved by a warm beam-pipe ferrite damper.

Abstract: A niobium cavity exhibiting high quality factors at high gradients is provided by treating a niobium cavity through a process comprising: 1) removing surface oxides by plasma etching or a similar process; 2) removing hydrogen or other gases absorbed in the bulk niobium by high temperature treatment of the cavity under ultra high vacuum to achieve hydrogen outgassing; and 3) assuring the long term chemical stability of the niobium cavity by applying a passivating layer of a superconducting material having a superconducting transition temperature higher than niobium thereby reducing losses from electron (cooper pair) scattering in the near surface region of the interior of the niobium cavity. According to a preferred embodiment, the passivating layer comprises niobium nitride (NbN) applied by reactive sputtering.