Tracking and k-modulation measurements in String II

This report summarizes the results of tracking and k-modulation measurements made in String II in October 2002. The main field was measured by fixed coils inserted in two quadrupoles and in one dipole of the String for various current excitations. A series of tracking runs was devoted to demonstrate that the ratio B2/B1 between the quadrupoles and the dipole field can be controlled and maintained constant to better than 10**-4 throughout a current ramp representative of the energy ramp in the LHC. Furthermore, k-modulation measurements were performed by modulating the current in the quadrupoles with a harmonic function. The frequency and the amplitude of the modulation was varied between 0.1 and 1 Hz, 0.5 and 5 A. The quadrupoles sustained this modulation without quenching, and the field produced was within 1 % of the expected value.