ZBASE User's Guide Version 1.1: an Impedance Data Base Program

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 LEP-II 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. The development of the {\bf ZBASE} 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 which allows easy access. Second, it should include information required for estimating the impact of the impedance on the beam dynamics. Third, the program should provide a user friendly graphical interface and fourth, it should provide an interface to the programs that are used for calculating the impedance data. Collecting not only the impedance data but also the input files for the programs that were used for calculating it and all data necessary for calculating stability threshold currents, greatly facilitates the recalculation of the threshold currents if the parameters change. For LEP-II, for example, the transverse mode coupling instability is expected to limit the maximum current in the machine. As the number of installed impedance components and the optics functions in the machine will change during the upgrade of LEP from 1996 to 1998 it is desirable to provide all the information required for estimating the instability threshold current in the data base and to provide an estimate for any stage of the upgrade. For the LHC, most of the impedance items are still in the design process and feedback from impedance calculations is desirable at this stage. A central data base that allows a semi-automatic recalculation of the impedance data once the geometry of an item changes will facilitate such a feedback.