Measured control characteristics of the half-cell 40mm aperture magnet string

The data presented here were obtained in the course of operating a five 40mm aperture dipole string. The eighty eight meter long string of dipoles was assembled to test the various proposed operational scenarios of the SSCL collider. As reported earlier, there had been a short control and system (data procurement) checkout run performed on an abbreviated two dipole string. The problems that were then uncovered with the exception of the high 20K shield heat load, were corrected. There has been over 5000 hours of running time on the system, 3000 hours on the five magnet string alone, and to date, no major problems or incidents have occurred. The quench (superconducting to normal transition) performance of the magnet string was excellent, with the exception of four premature quenches that occurred during power supply commissioning. The operational parameters were all found to be manageable or equal to or greater than design. The operational heat loads were within the budget with the exception of the 20K circuit which was a factor of three too high. The relative internal voltages of the magnets have been higher than previously measured in the shorter string by a significant amount. There will be a discussion of concerns and problems plus their possible solution. 6 refs