Kyushu University [Miyazaki Hiroshi (Professor) Faculty of Information Science and Electrical Engineering, Department of Electrical Engineering]

Miyazaki Hiroshi

Last modified date：2024.04.24

Professor / Department of Electrical Engineering / Faculty of Information Science and Electrical Engineering

Papers

1.	Research and Development of a High-field Coil System:– Development of a high-temperature superconducting magnet for ultrahigh-field MRI – A project for developing of RE₁Ba₂Cu₃O_7-δ (REBCO) magnets to be utilized in ultrahigh-field magnetic resonance imaging (MRI) was started in 2013. Our final targets are 9.4 T MRI systems for whole-body and brain imaging. In this project, two different development approaches towards the final target were planned. One is a small REBCO coil that can generate 10 Tclass magnetic fields, which is the same level as the target magnetic field. The other is a conduction-cooled 1.5 T REBCO MRI magnet that has a room-temperature bore of 396 mm, which is as large as those of mid-sized model magnets. These results were reflected in the design of a conduction-cooled 9.4 T REBCO magnet for whole-body MRI systems. .
2.	Development of conduction-cooled REBCO superconducting coils:– investigation of the thermal runaway currents and mechanical properties of impregnated single-pancake coils– We are developing conduction-cooled REBCO superconducting coils. We first observed thermal runaway currents of the coils during the process of making impregnated single-pancake coils with an outer diameter of 300 mm with REBCO- coated conductors and conduction-cooling them using a GM cryocooler. In addition, we performed a numerical simulation of the electromagnetic and thermal behavior of the coils with the critical current properties of the REBCO tapes through use of a threedimensional heat conduction equation. Comparing the observed results with the theoretical prediction, we confirmed the theoretical predictability of the thermal runaway currents of the single-pancake coils. These results suggest that the winding and impregnation were successfully carried out without degradation of the properties of the prepared REBCO tapes. Further, in testing conducted on an impregnated small coil in a 4 T background magnetic field, we confirmed that the impregnated coils could withstand hoop stress as high as the mechanical strength of the REBCO tape itself..
3.	Study of the basic properties of REBCO-coated conductors for HTS coil technology:– evaluation of delamination characteristics and numerical prediction of flux flow characteristics–.

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