Parametrization of AmPS magnets for the control system

Parameterization of the AmPS magnets (dipoles, quadrupoles, sextuples and steering coils) has been performed by precisely measuring the field integrals of each magnet type as a function of the excitation current. In order to guarantee a good accuracy of the measurements the Hall probe used was carefully calibrated. This magnet data has been imported into the machine-simulation program DIMAD and a complete refit has been made for various machine properties like the achromatic curved section, the tune, the chromaticity, etc. The algorithms have been implemented in the control system and were calibrated against the beam energy. From the start of the commissioning (spring 1992) the calculated settings and the measurement results proved to be in good agreement: guiding the first beam through the ring took only a few minutes. Also the first measurements of the betatron tune are in agreement with the calculated value using the parameterization of the ring magnets. Futhermore local closed orbit bumps can be generated in the following regions: the injection area, the extraction area, the r.f. cavity area and the internal target area. The performance of this program also indicates the magnet settings are correct