Impedance of a perforated liner and its impact on the SSC Collider

Various approaches (analytical, numerical, and experimental) have been tried to investigate the impedance and wakefields of a liner. At low frequencies, the results obtained from different approaches are in agreement. At high frequencies, the simulations show that the resonance peaks and the associated long term wakes are related to the periodicity of the hole distribution. The dependence of the impedance on the size, shape and pattern of the holes and slots has been studied. The rounded short slots of random distribution is recommended for minimizing the impedance. The RF coupling between the area inside the liner and the annulus is negligibly small in the frequency range of interest. The impact of the liner on the safety margin and resistive wall instability has been studied