Polyhedral Superconducting Cavity for Particle Accelerators

A polyhedral cavity design is being developed for particle accelerators, with particular potential application to future linac colliders. In essence it is a polyhedral analog of a multi-cell cavity, but the beam's eye view of the boundaries is a polyhedron instead of a figure of revolution. A multi-cell cavity string is formed as a Roman arch assembly of polyhedral wedges; each wedge has its inner surface contoured to form the ellipsoidal shape desired for the accelerating mode. The polyhedral cavity design has been studied numerically and several significant results are reported. Its Q should be comparable to that of a TESLA cavity. The joints between wedge segments offer the possibility to internally suppress all dipole-type higher-order modes by intercepting and terminating azimuthal currents. The Nb surface is provided as a thin foil bonded to a solid copper wedge machined to the desired contour. The wedge provides stiff support so Lorentz detuning is largely eliminated, and the superfluid refrigeration could be integrated within the wedges so no pool cryostat is required.