Magnetic measurement system for harmonic analysis of LBL SSC model dipoles and quadrupoles

Specialized hardware and software developed to facilitate harmonic error analysis measurements of 1-m long Superconducting Super Collider model dipole and quadrupole magnets are described. Cold bore measurements feature cryogenic search-coil arrays with high bucking ratios that also have sufficient sensitivity to make room-temperature measurements at the low magnet currents of approximately 10 A. Three sets of search coils allow measurements of the center, either end, and/or the axially integrated field. Signals from the search coils are digitally integrated by a voltage-to-frequency converter feeding an up-down counter. The data are drift-corrected, Fourier analyzed, converted to physical quantities, and printed and plotted. A cycle of measurements including data acquisition, processing, and the generation of tabular and graphic output requires 80 s. The vast amount of data generated (several hundred measurement cycles for each magnet) has led to the development of three types of postprocessing for the dipole and quadrupole systems: (1) re-creation of the real-time output, (2) generation of an SSC prompt report, and (3) production of general-purpose spreadsheet/graphical output.