2D and 3D collimator impedance modeling and experimental measurements

In order to safely operate high energy particle accelerators, an advanced collimation system in terms of absorber material choice, alignment precision and low impedance impact is often required. In this work we will summarize the recent advancement on collimator impedance modeling starting from simple 2D structures, involving resistive jaws and transition tapers, to complex 3D structures, involving multilayer coatings, embedded beam position monitors, contact fingers, and jaw segmentation. Measurements techniques based on the stretched and resonant wire methods will be presented in order to support simulations, together with DC and RF resistivity measurements of the jaw material samples. Recent single collimator beam based measurements will be presented as well.