ZBASE User's Guide Version 1.2
An Impedance Data Base Program
Oliver S. Brüning
November 12, 1996
Abstract:
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 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.
