RF Losses in Superconducting Lead Cavities

Abstract

At the present time the only materials seriously considered for superconducting accelerators are lead and niobium. In the electron linacs under construction at Stanford and the University of Illinois cylindrical niobium cavities are being employed. The relatively uncomplicated geometry of such cavities permits the fabrication and annealing procedure to be approached in a straightforward (though expensive and time-consuming) manner and offers the optimum final energy gradient for these accelerators. However, the complicated geometrical structures (e.g., drift tubes or helically loaded wave guides) required for low phase velocity heavy-ion accelerators make the use of niobium less appealing. In contrast, lead may be easily plated on even very complicated structures with a minimum degree of difficulty and cost.