Relaxation properties of magnetic force between a magnet and superconductor in an unsymmetrical levitation system
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Abstract:
We present an experimental study of the relaxation of vertical and horizontal force components in an unsymmetrical high-temperature superconducting levitation system, with different initial cooling processes, after fixing the levitated body statically in a given position. It was found that the values of the relaxation measurements of the levitation force and lateral force remained constant or increased with time after vertical and horizontal traverses. The phenomenon has been theoretically described based on the Bean model and the thermally activated flux creep theory. The criterion developed in the present work is considered to be suitable for providing qualitative predictions of the relaxation properties in the levitation force and lateral force.Keywords:
Magnetic Levitation
We have studied a magnetic levitation system using magnetic shielding effect of a superconducting bulk made of gadolinium. We extended the experimental apparatus from the previously used basic model to parallely placed 2-basic model. The peak levitation force in the 2-basic model was more than double the force in the basic model due to the bending of magnetic force lines. We could successfully obtain the large levitation force.
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Spin-stabilized magnetic levitation
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An outline of the magnetic levitation project in Japan is given. Research has been concentrated on levitation system utilizing electromagnetic repulsive force between a normal metal track and on-board superconducting magnets. Development of levitation magnets together with other items basic for a levitation system is given.
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Spin-stabilized magnetic levitation
Ground transportation
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Abstract We present results obtained with an original hybrid set-up permitting to increase strongly the levitation force of Superconducting Magnetic Levitating (SML) systems. We compare levitation force measurements carried out with this set-up to measurements carried out with a conventional one. We investigate the stability of the proposed system by measuring the lateral (or restoring) force. We show how to calculate the measured levitation and lateral forces from: (i) those measured in the conventional configuration and (ii) the repulsive force between the magnets included in the system. We discuss the conditions of stability of the proposed system as well as the consequences that its introduction could have on the future of SML MAGLEV trains.
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It is beneficial to apply a high-Tc bulk superconductor as a large flux source to an electromagnetic levitation system, which needs large amounts of levitation force. We made an attractive-type electromagnetic levitation system using a hybrid magnet that mainly consisted of bulk superconductor and control coils to confirm the principle of the levitation, and obtained characteristics of its system by both experiment and numerical analysis with magnetic circuit calculation.
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We have developed a magnetic levitation system using a magnetic shielding effect of high temperature superconducting bulks. We have already succeeded to demonstrate principle of the levitation. In the paper, we tried to increase the levitation force. Firstly, when a ferromagnetic plate was put underside of a permanent magnet, the levitation force increased. And when the underside ferromagnetic plate was protruded from the magnet, the levitation force effectively increased furthermore. Lastly, the levitation force exceeded vehicle weight and the stable levitation became possible.
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Electrodynamic suspension
Spin-stabilized magnetic levitation
Maglev
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Recently, with the advance of materials processing techniques, such as top-seeding and melt-texturing (TSMT) method, very large single-grained Y-Ba-Cu-O (YBCO) samples up to several centimeters in diameter can be produced. Each sample is capable of levitating over kilograms of weight. A HTS magnetic levitation (MagLev) transportation prototype has been constructed at National Cheng-Kung University (NCKU) to validate the concept of HTS-MagLev system based on Meissner effect. This HTS-MagLev is an inherent stable levitation system, unlike traditional MagLev system that requires sensors and feedback circuits to dynamically adjust its unstable levitation position. In this report, the results of various magnetic levitation parameters, such as different permanent magnet configurations, relative levitation stability, levitation force, etc., as well as magnetic field intensity and distribution will be discussed.
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Electromagnetic suspension
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A high precision superconducting levitation system for gravity measurement has been developed, which used the levitation of a superconducting sphere by the magnetic field of two superconducting coils. The magnetic levitation is designed to provide independent adjustment of the levitating force and the force gradient. A Gifford-McMahon (GM) cryocooler is employed to cool down the system. This paper reviews the construction and operating characteristics of the system. The test results show that the earth tide signal was detected by the system.
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Spin-stabilized magnetic levitation
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This paper presents two actuators for levitation using repulsions of permanent magnet and two magnetic levitation tables using the actuators. Here, one actuator for levitation consists of one fixed magnet and one moving magnet, and the other actuator consists of two fixed magnets and one moving magnet. The moving part of the magnetic levitation table contains the moving magnets. repulsive forces caused by the permanent magnets are linearized, and then the equation of motion of the moving part of the table is derived. Using the equation of motion, stability conditions of the moving part are deduced. The stability conditions are analyzed for positional relations of the moving magnets and the minimum number of active control required for stable system. As a result, in the each case of magnetic levitation tables, the requirements for stabilization are expressed by the positional relations and the number of the active controls.
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Increased Levitation Force in Magnetic Levitation System Using Magnetic Shielding Effect of HTS Bulk
We studied a levitation system that uses the magnetic shielding effect of a high-temperature superconducting bulk. As the levitation force was insufficient in our former experiments, ferromagnetic plates and bars were added to the superconducting bulk to increase the levitation force. Experimental results showed that the levitation force increased when small plates and bars were used. The peak levitation force exceeded the weight of the moving part in our experimental system, thus enabling the moving part to be lifted.
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Spin-stabilized magnetic levitation
Maglev
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In this report, a stabilization method for a repulsive-type magnetic levitation system using a superconducting magnetic bearing is proposed. A repulsive-type magnetic levitation system can generate a large levitation force. However, this system is unstable since there is no horizontal stabilization and moment of force without control. Incidentally, a high-temperature (high-Tc) superconducting magnetic bearing can always stabilize levitation without control. Moreover, it is possible to cancel the unstable force of repulsive-type magnetic levitation by increasing the rigidity of the high-Tc superconducting bearing. In this study, the unstable force of repulsive-type magnetic levitation was stabilized by combining these two methods. In addition, the levitation system generated a large levitation force.
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Spin-stabilized magnetic levitation
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Rigidity (electromagnetism)
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