HOM BEAM COUPLING MEASUREMENTS AT THE TESLA TEST FACILITY (TTF)

The proper damping of the higher order modes (HOM) of the TESLA superconducting accelerating cavities is a crucial requirement for the emittance preservation in the TESLA linacs. Experiments of HOM beam excitation have been performed on the accelerating modules of the TTF linac, with a recent emphasis on the measurement of the beam coupling and HOM polarization, in contrast to the frequency and damping parameters which are easier to measure. We report on the analysis of these experiments and on the measurement results.