Idle superconducting RF cavities for bunch focusing

In the feasibility study for a B-Meson factory using the CERN ISR tunnel and the LEP injection system (BFI), a combination of normal conducting (NC) and superconducting (SC) RF cavities has been proposed as an alternative in the context of upgrading the luminosity towards 10/sup 34/ cm/sup -2/ s/sup -1/. The steady state and dynamic behavior of a single RF system, in the presence of beam loading, has been already largely treated. Extending the analysis to the more general case of two RF systems coupled through the beam was studied by P. Merchand (1990). No major critical issues, as compared to conventional methods, were encountered in the context of the BFI. On the contrary, the partial or complete separation of functions, powering and longitudinal focusing, characteristic of this system, makes it particularly flexible. The main results of this study and examples of applications are presented. The possibility of testing the bunch shortening provided by idle SC cavities in an existing storage ring is also discussed.<>