Preliminary design of a scanning resonant cell for beam screen surface impedance measurements

In modern particle accelerators, beam screens play an essential role. Here, the surface impedance becomes one of the characteristics responsible for the performance. A scanning device for nondestructive characterization of the internal surface of the beam screens in terms of its surface resistance is here proposed. The device is based on a dielectric resonator working on the TE011 resonant mode, the most reliable technique for surface impedance measurements. We use extensive electromagnetic simulations to determine the optimal geometry of the dielectric-loaded resonator. We paid particular attention to the low operation frequency and to the sensitivity on the curved inhomogeneous walls of the beam screen within the octagonal-shaped beam screen here considered as an example.