Measurement of the Longitudinal Coupling Impedances using Short Electron Bunch

The longitudinal coupling impedance in modern storage rings has to be limited to ensure beam stability. To de- termine the real part of the narrow band impedance we suggest to measure the loss factor of the resonant modes using short electron bunch passing through the tested el- ement. This method is also suitable for the measurement of the longitudinal impedances for nonrelativistic particles, that is important for some modern projects of ion storage rings designed to achieve ordered structure in the ion beam. The desired value of relativistic parameter can be chosen by adjusting energy of the electron bunch. The impedance of the fundamental mode of the wall current monitor was measured using electron bunch from photogun. The dependence of impedance on beam energy is measured in the range . Comparison of experimental data with computer simulation is done.