MEASUREMENT RESULTS

We report the results of impedance measurements, per-formed by the triaxial wire method, on a 2 m long model of the LHC vacuum chamber. The model consists of an inner screen (liner) with pumping holes and of the outer vacuum chamber. The transmission coefficient for differ-ent numbers of holes with various radii confirms the role played by TEM modes, propagating at the same speed of the beam particles in the coaxial structure formed by the liner and the outer vacuum chamber. We also compare the results of these measurements to analytical estimates of the coupling impedance