Superconducting Cavities for the APT Accelerator

One type of design for an Accelerator Production of Tritium (APT) facility being investigated at LANL consists mainly of a linear accelerator using superconducting rf cavities for the acceleration of a high current cw proton beam. For electron accelerators with particles moving at almost the speed of light (β=1.0), resonators with a rounded shape, consisting of elliptical, circular and straight sections, are well established. They are referred to as ``elliptical'' cavities. For the APT-design, this shape has been adapted for much slower proton beams from a β of less than 0.64 to slightly above 0.82. This is a new energy range, in which resonators of an elliptical type have never been used before. Simulations with the well-proven electromagnetic modeling tools MAFIA and SUPERFISH were performed. The structures have been optimized for their rf properties as well as for beam dynamics requirements. Single cell test cavities are under construction and will be tested in our structures laboratory. Their performance in terms of obtainable gradients, Q and multipacting behavior, as well as a comparison of the major rf parameters with the results of the cavity simulations, will be reported.