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京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第21546号 / 理博第4453号 / 新制||理||1639(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)准教授 池田 隆介, 教授 前野 悦輝, 教授 川上 則雄 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

Thesis: B.S., Massachusetts Institute of Technology, Department of Mechanical Engineering, 1980 / Includes bibliographical references. / by Christopher P. Hamkins. / B.S. / B.S. Massachusetts Institute of Technology, Department of Mechanical Engineering

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Includes bibliographies. / by Stanley R. Shanfield. / Ph.D.

A Superconducting Magnetic Energy Storage (SMES) system is a very efficient storage device capable of storing large amounts of energy. The primary applications it has been considered till now are load-leveling and system stabilization.This thesis explores new applications/benefits of SMES in power systems. Three areas have been identified. • Using SMES in conjunction with PV systems.SMES because of their excellent dynamic response and PV being an intermittent source complement one another.A scheme for this hybrid system is developed and simulation done accordingly. • Using SMES in an Asynchronous link between Power Systems. SMES when used in a series configuration between two or more systems combines the benefits of asynchronous connection, interconnection and energy storage. A model of such a scheme has been developed and the control of such a scheme is demonstrated using the EMTP. The economic benefits of this scheme over pure power interchange, SMES operation alone and a battery/dc link is shown. Improvement of transmission through the use of SMES. SMES when used for diurnal load leveling provides additional benefits like reduced transmission losses, reduced peak loading and more effective utilization of transmission facility, the impact of size and location on these benefits were studied, and if used as an asynchronous link provides power flow control. / Master of Science

Nuclear magnetic resonance—a bulk, local probe of materials’ electronic properties—has been significant for theories of high-temperature superconducting cuprates. However, more recent NMR experiments revealed several contradictions in the early interpretation of the NMR data. This cumulative thesis, comprised of six publications, aims to develop a new phenomenology based on the entirety of Cu and O NMR shift and relaxation data. The data revealed that a suppression of the Cu shifts is behind the failure of the Korringa relation, while the Cu relaxation measured with one direction of the field (c||B0) is similar for all cuprates and is Fermi-liquid like. The Cu shift and relaxation anisotropies could be explained by assuming two-spin components with different doping and temperature dependencies. A later analysis of all planar O shift and relaxation showed that a metallic-like density of states is ubiquitous to all the cuprates, irrespective of doping and material, and carries a temperature-independent but doping-dependent pseudogap, as similarly seen in the electronic entropy. This temperature-independent pseudogap is behind the suppression of the Cu shifts, but it has no influence on the Cu relaxation. Additionally, the Cu shifts measured with the field perpendicular to the c-axis reveal a family dependence. We propose a two-spin component model, explaining the family dependence in the Cu shifts, the complex Cu shift anisotropy and relaxation, and the disparity in the temperature dependence between the Cu and O shifts. This model also accounts for the missing negative shift and the long-standing Cu orbital shift discrepancy. While these conclusions are phenomenological, they must be explained by a detailed theory of the cuprates

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Distribution systems across most parts of the globe are highly radial in nature. As loads are gradually increased on a particular distribution system, a higher operating current state leading to increased fault current levels is attained. Hence, the relay co-ordination is disturbed and equipments such as feeders and circuit breakers need to be replaced with higher rating so that they can handle the new currents often leading to expensive retrofit costs. The use of fault current limiter (FCL) is proposed to mitigate the effects of high current levels on a distribution system. A comprehensive and up-to-date literature review of FCL technologies is presented. Detailed efforts of an in-house developed behavioral superconducting FCL model are delineated, including FCL control algorithm and its implementation in PSCAD®/EMTDC environment. Results from simulation studies are investigated and compared to an actual FCL commissioned by Z-energy to highlight the effectiveness of a generic model without having to access proprietary details. Extending those concepts, a solid-state and hybrid type of limiter is also modeled and it results discussed. Finally, an impact assessment is conducted on the distribution protection scheme, due to the FCL being inserted and subsequently operated in the distribution system. / Master of Science

Les travaux de cette thèse portent sur un insert dipolaire de supraconducteur à haute TC (SHT) en utilisant un câble multi-rubans torsadé pour un accélérateur des particules dans le cadre du projet EuCARD2 au CERN. L’insert dipolaire SHT est la seule possibilité aujourd'hui pour aller au-dessus de 16 T pour le futur accélérateur des particules à haute énergie. Deux spécifications de cet insert SHT sont les grands courants de fonctionnement (> 10 kA) et les champs de fond élevés (> 13 T) conduisant à des conditions de fonctionnement sévères. Pour répondre à ces attentes, un premier insert SHT de multi-rubans torsadé/ type de bloc est proposé sur la base des approches analytiques, numériques et expérimentales. Les travaux sont principalement classés dans le design d’insert dipolaire et le design de câble multi-rubans torsadé. Cette thèse se terminée avec la meilleure solution pour l’insert SHT de multi-rubans torsadé/ type de bloc en utilisant le câble partiellement isolé. / This Ph.D. deals with a high Tc superconducting (HTS) dipole insert using a twisted stacked cable for a particle accelerator in the framework of EuCARD2 project in CERN. The HTS dipole insert is the only possibility today to go above 16 T for the future high-energy particle accelerator. Two specifications of these HTS insert are large operating currents (> 10 kA) and high background fields (> 13 T) leading to severe operating conditions. To meet these expectations, a first Twisted Stacked/ Block-type HTS insert is proposed based on analytical, numerical and experimental approaches. The works are mainly classified into dipole insert design and twisted stacked cable design. This Ph.D. ends with the best solution for Twisted Stacked/ Block-type HTS insert using partially-insulated cable.

Les tokamaks visent à produire de l'énergie par fusion thermonucléaire en chauffant un plasma d'hydrogène jusqu'à 150 millions K et en le confinant à l’aide d’un champ magnétique intense créé par des aimants transportant d’importants courants. La supraconductivité est un atout précieux ici car permettant de réduire la taille des aimants et leur consommation énergétique en contrepartie d’un refroidissement cryogénique. Cependant, dans les tokamaks, des variations de champ magnétique apparaissent (ex : décharge du solénoïde central) et génèrent des pertes par induction dans les aimants. Si leur température augmente trop, ils peuvent perdre leur état supraconducteur lors d’une transition brutale appelée "quench": afin de les protéger, ils sont déchargés de leur courant entraînant ainsi la perte du plasma. Nous avons concentré notre travail sur la modélisation de ces pertes car leur connaissance est cruciale pour le bon dimensionnement du refroidissement des aimants et la prédiction des limites opérationnelles du tokamak. Afin d'améliorer la compréhension physique de ce phénomène complexe et de proposer des solutions simples mais réalistes, facilement intégrables dans des plateformes multiphysiques déjà fortement sollicitées par la modélisation d'autres effets, nous avons choisi d'adopter une approche analytique. Les câbles présents dans les tokamaks ayant une architecture assez complexe (centaines de brins torsadés ensemble), nous avons mené des études analytiques et expérimentales aux différentes échelles du câble; nous comparons ensuite les résultats de notre approche à ceux d'autres modèles existants (ex : numériques) et, lorsque cela est possible, à l'expérience. / Tokamaks aim at producing energy by thermonuclear fusion heating a hydrogen plasma up to 150 million K and confining it with an intense magnetic field created by magnets carrying important currents. Superconductivity is a very valuable asset in this field since it allows to reduce the size of the magnets and their energy consumption in exchange for cooling them down to cryogenic temperatures. However, in tokamaks, magnetic field variations occur (e.g. due to the central solenoid discharge) and generate induction losses in the magnets. If their temperature increases too much, they lose their superconducting properties in a brutal transition called "quench": to protect their integrity, they are then discharged and the magnetic confinement of the plasma is lost. We have therefore focused on the modeling of these losses - more precisely on the “coupling losses” - since their knowledge is crucial to safely adapt the cryogenic cooling of the magnets and predict the operating limits of the tokamak. In order to both enhance the physical understanding of this complex phenomenon and provide simple but realistic solutions that can easily be integrated in multiphysics platforms already heavily solicited by the modeling of other effects, we have chosen to adopt an analytical approach on this problem. The cables commonly considered for tokamaks presenting a rather complex architecture (several hundreds of strands twisted together in specific patterns), we have carried out analytical and experimental studies at the different scales of the cable; we then compare the results of our approach to other existing ones (e.g. numerical models) and, when possible, to the experiment.