Harmonic-error-analysis measurements of dipole and quadrupole magnets at Lawrence Berkeley Laboratory

Error harmonics are detected using slowly rotating search-coil arrays feeding a digital integrator. The fundamental signal is detected during the first rotational cycle. The search-coil arrays are reconfigured to ''buck'' the fundamental and lower harmonics during the second rotational cycle, allowing the measurement of higher harmonics with excellent resolution. Data are first drift corrected, then harmonic analyzed using the fast Fourier transform technique. The measurements, data processing, and generation of both tabular and graphic output require about 80 seconds. Data are later postprocessed using spreadsheets allowing easy manipulation and comparison or measurements during a test series and between magnets. Hardware and software are described. Accuracy, precision, and resolution are discussed, and the measurement technique for Superconducting Super Collider (SSC) model magnets are described