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Description
Recently, a Wireless Power Transmission (WPT) system has been attracting attention for automobiles and electric railways. However, the power transmission efficiency in the conventional WPT system composed of copper coils is not high enough due to large resistance. Therefore, we have investigated the effectiveness of applying REBCO coils to WPT system. Since the increase AC loss of the REBCO coil leads to not only the temperature rise of the REBCO coil but also the reduction in the power transmission efficiency and the transmission power of the WPT system, it is important to reduce the AC loss of the REBCO coil. Therefore, in order to reduce the AC loss of the REBCO coil, it is necessary to investigate the magnetic properties of REBCO tape at low temperatures. In addition, it is necessary to evaluate the magnetic properties and losses of copper stabilizer, hastelloy substrate and so on. We have been developing equipment to evaluate the magnetic properties of magnetic materials such as non-oriented /grain-oriented electrical sheet, and our single sheet tester (SST) is one of them. In this study, we wanted to try to evaluate the magnetic properties of the component of REBCO wire under low temperature conditions using the SST. Since the SST is generally used at room temperature, it needed to modify the SST for cryogenics in order to measure the magnetic properties of REBCO wire and its component. Therefore, the existing SST was designed and fabricated in a small size that can be mounted on a conduction cooling system using 4K cryocooler. After confirming the sufficient measurement accuracy of the SST at room temperature, the magnetic properties of component of the REBCO wire were measured at low temperatures from 4.5 K to 40 K by the conduction cooling system and measured the results will be reported.
