Visualization of magnetic field direction in an electric motor using polarized pulsed neutron imaging

Hiroi, Kosuke  ; Shinohara, Takenao   ; Hayashida, Hirotoshi*; Parker, J. D.*; Oikawa, Kenichi   ; Harada, Masahide   ; Kai, Tetsuya   ; Arai, Masatoshi*

We have been developing an imaging technique using polarized pulsed neutron for quantitative evaluation of magnetic field in industrial equipment, e.g. an electric motor and an electric transformer, etc. To reduce the power loss of these products, it is important to quantitatively evaluate not only strength of an internal field but also directional distribution. In this study, we attempt to evaluate direction of a field in the gap between the rotor and the stator of a model electric motor. Magnetic imaging experiment was performed at BL10 "NOBORU" in Materials and Life science experimental Facility (MLF) of J-PARC. In this experiment, we changed the quantized axis of a neutron spin using spin-rotators and obtained polarization images with various neutron spin directions. By analyzing change in polarization depending on neutron spin direction, we successfully obtained field-direction distribution image in the model motor.