報告書番号

H03

タイトル（和文）

ポインチングベクトル法による超電導コイルの交流損失測定に関する研究 -超電導コイルの高精度交流損失測定法の開発と大型機器への適用の提案-

タイトル（英文）

AC loss measurement of superconducting coils by the Poynting vector method

概要 （図表や脚注は「報告書全文」に掲載しております）

超電導実用化における最重要な技術的課題として交流損失が挙げられる。交流損失は、機器の効率を下げるばかりでなく、機器の冷却に関わるため機器全体の構成を複雑にし、機器のサイズを大きくする。本報告は、この交流損失を測定する技術開発に関する研究である。 本報告では、実際の長尺の超電導線材や導体で作った単層や多層のソレノイドコイルに適応可能な新しい交流損失測定装置を開発して、その有用性を実証している。この装置は、ポインチングベクトル法による損失測定であり、実際の試料に印加する交流電流と磁界に関して制約条件が極めて少ない点が、従来法に比べて優れている。さらに、電力貯蔵装置のような大型で複数のコイルシステムに対応できる、ポインチングベクトル法を応用した新しい診断と監視システムの提案を行い、その有用性を明らかにしている。

概要 （英文）

This thesis mainly comprises the development of new systems to measure AC losses in superconducting coils by means of the Poynting vector method. This system is applicable for various shapes of single or multi layer coils wound with long superconducting wires or conductors. And an advantage of the system is that there is very little limitation for the measurement condition with transport currents and external magnetic field. This system of ac loss measurements is, therefore, more superior than existing system.This thesis has 5 chapters. In Chapter 1, a wide range of application of superconductivity technologies is introduced. And then it is shown that the study related to ac losses in superconducting coils is one of main points for practical uses, and that the loss measurement is necessary in order to discuss the reduction of losses in coils. Furthermore, existing measuring methods are classified into a few categories, and their merit and demerit are also described for the sake of understanding the significance of this thesis. Finally, purposes and contents of this thesis are described.In Chapter 2, both the principle and the usefulness of loss measurements by Poynting vector method are discussed. Then, the limitation of measurement conditions of the existing method applicable for short, straight superconducting tapes is described. Next, a new loss-measurement system by the Poynting vector method applicable for coils wound with long wires or cables is proposed. Furthermore, the experiment of loss measurements for various shapes of coils carried out to clarify the effect of the short coil axes on the measured data is described. A suggestion of treatment in case of short coil axes is shown from the obtained data.In Chapter 3, the new system of loss measurements proposed in the previous chapter is demonstrated to confirm its validity and usefulness. First of all, sample coils wound with Ag-sheathed multifilamentary Bi-2223 tapes are shown and the practical circuit of this measurement system is also shown. Then measured data in the simultaneous sweep case of transport currents and transverse external magnetic fields are shown, where distributions of local electric fields and magnetic fields are also shown to discuss the loss properties.In Chapter 4，another new system of Poynting vector method applicable for big and plural coil systems is proposed. This system has a superior merit that there is no limitation of coil axis length. This system is expected as a candidate of surprising breakthrough technologies; this may be useful as new systems of diagnosis and monitor of large and plural superconducting coils for SMES and so on. A principle and special feature of this system are described and then some data of demonstration of this system are also shown.In chapter 5, this study is generalized; the obtained results in this thesis are described to conclude.

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