Magnetic Field Evaluation of Multipole Permanent Magnets by Harmonic Coil with Novel Calibration Technique

We developed multipole permanent magnets that had a variable main magnetic harmonics. In order to evaluate the variation, we also developed a harmonic coil with tangential single-turn coil. Although one of the systematic errors of the harmonic coil is uncertainty of the position of coil wire because a harmonic coil is usually used by multi-turn coil, the systematic error was reduced by using single-turn coil. We calibrated the wire’s position by using a pair of attracting pieces of 10 mm square NdFeB magnets, so that the influence of the position was calculated. Then we evaluated magnetic field of multipole permanent magnets, so that we discuss about performance of the magnets.