Induction-Coil Measurement System for Normal- and Superconducting Solenoids

The magnetic measurement of solenoids relies on different methods to characterize the field quality and locate the magnetic axis. Usually, Hall mappers and stretched-wire systems are used for these tasks. This paper presents an alternative, fluxmetric method to measure the radial field dependence and the magnetic axis with a single instrument. The solenoidal-field transducer is based on a disc-shaped induction-coil array with concentric coils and 90 deg. arc segments mounted on a translation stage. This allows to sample the magnet along its axis and to extract both the longitudinal and transversal field components. The design, development, and validation of the new instrument are described. The induction coil, which is the core of this instrument, is fabricated in printed-circuit board technology, which has become the new standard for these applications. Results of recent measurements of a normal-conducting solenoid magnet are given.