This paper presents an experimental observation of the rotation of a magnetostrictive motor about an arbitrary axis using a Terfenol-D rod and a helical magnetic field. Mangetostrictive motors consist of a solenoidal coil that generates a longitudinal magnetic field, a toroidal coil that generates a circumferential magnetic field, a Terfenol-D rod, a stator, a rotor, and so on. Two experiments were conducted in order to confirm the motors rotation about an arbitrary axis. The first measures the twist angle of the Terfenol-D rod and the second measures the tilt angle of the rotor with respect to the z-axis. The twist angle can be determined by the strain value of the strain gauge attached to the Terfenol-D rod. The tilt angle was obtained using a new trajectory tracking method with five cameras. When the ratio between the circumferential magnetic field and the longitudinal magnetic field changes, the twist and tilt angles also change.

This study presents the development of a magnetostrictive control rod position indicator (Mag-CRPI) for improving safety of nuclear power generation. Mag-CRPI principle is based on two magnetostrictive effects: The Wiedemann effect and the Villari effect. The position may be estimated by multiplying time-of-flight (TOF) of the elastic wave from the cursor magnet to the sensing coil, and a sound speed of the magnetostrictive wire. A Mag-CRPI prototype has been designed and built. Experiments are conducted to characterize the Mag-CRPI. Change of the TOF is obtained with cursor magnet movement interval of 100 ㎜. Averaged position error is estimated to be 0.002m over the entire measuring length. Based on experimental results, the performance of Mag-CRPI is validated, thereby confirming feasibility of a nuclear reactor-internal control rod.