Low impedance bellows for high-current beam operations

In particle accelerators, bellows are commonly used to connect beamline components.Such bellows are traditionally shielded to lower the beam impedance. Excessive beamimpedance can cause overheating in the bellows, especially in high beam current operation.For an SRF-based accelerator, the bellows must also be particulate free. Many designs ofshielded bellows incorporate rf slides or fingers that prevent convolutions from beingexposed to wakefields. Unfortunately these mechanical structures tend to generateparticulates that, if left in the SRF accelerator, can migrate into superconductingcavities, the accelerator's critical components. In this paper, we describe a prototypeunshielded bellows that has low beam impedance and no risk of particulate generation.