An Impedance Data Base Program for LEP2 and the LHC

The development of an impedance data base program was motivated by the changing impedance budgets in the LEP and LHC machines and the resulting need to recalculate the instability thresholds for different parameters. For LEP, the changes are implied by the LEP2 upgrade and for the LHC, the impedance data for most items is still being calculated and continues to change as the geometries of the impedance components converge to a final design. In both cases, feedback from the impedance calculations is desirable. A central data base that allows a semi-automatic recalculation of the impedance data once the geometry of an item changes facilitates such a feedback. The development of the program was guided by four goals. First, the data base program should collect the impedance information in a central place and in a standard format allowing easy access. Second, it should provide procedures for estimating the impact of the impedance on the beam dynamics. Third, the program should provide a user friendly graphical interface to the data base and all external programs that are used for calculating the impedance data. Fourth, it should store he input files for the external programs allowing a semi-automatic recalculation of the impedance data once the geometry of an item changes.