Observation of the magnetic field distribution leaked from an electric transformer using pulsed polarized neutron imaging

Hiroi, Kosuke  ; Shinohara, Takenao   ; Hayashida, Hirotoshi*; Parker, J. D.*; Kai, Tetsuya   ; Kiyanagi, Yoshiaki*

Observation of magnetic fields emanating from electromagnetic devices gives important information on not only their structural and functional soundness but also on energy loss under operating conditions. A magnetic imaging technique using pulsed polarized neutrons would be suitable for direct observation of such magnetic fields because it enables us to visualize the field distributions in both massive objects and free space with a large field of view up to several square centimeters. We have developed such a pulsed polarized neutron imaging technique at BL22 RADEN at the Materials and Life Science Experimental Facility (MLF) of J-PARC and performed demonstration studies. In this presentation, we report recent results of a leaked field study from the operating electric transformer and discuss the relationship between the eddy current loss in the step-lap core and the leaked field distribution.