Measurements and model calculations of forces betpeen a magnet and granular high-Tc superconductor

Johansen, T. H.; Bratsberg, H.; Riise, Anjali B.; Mestl, H.; Skjeltorp, A. T.

doi:10.1016/0964-1807(94)90043-4

Cited by 12 publications

(5 citation statements)

References 15 publications

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“…39,38 The authors assumed that the grains are in the critical state model with an uniform magnetization M and obtained good agreement between the experimental results and the calculations.…”

Section: Introductionsupporting

confidence: 58%

Calculation of the hysteretic force between a superconductor and a magnet

Qin

Liu

et al. 2002

Phys. Rev. B

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The magnetic levitation forces exerted on a high-temperature superconducting ͑HTS͒ disk by a cylindrical permanent magnet ͑PM͒ are calculated from first principles for superconductors with finite thickness. The current j( ,z) and field B( ,z) profiles in the HTS in the nonuniform magnetic field generated by the PM are derived. The levitation force depends nonlinearly on the critical current density j c and on the thickness of the HTS. The flux creep is described by a current-voltage law E( j)ϭE c ( j/ j c ) n , from which we show that the levitation force depends on the speed at which the PM approaches or recedes from the HTS, which accounts for the experimentally observed force creep phenomenon. The stiffness of the system is derived by calculating minor force loops. The numerical results reproduce many of the features observed in experiments.

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Section: Introductionsupporting

confidence: 58%

Calculation of the hysteretic force between a superconductor and a magnet

Qin

Liu

et al. 2002

Phys. Rev. B

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“…The critical-state model [83,84] is often invoked to explain many of the levitational phenomena [85][86][87][88][89][90][91][92][93][94][95][96][97].…”

Section: Critical-state Modelmentioning

confidence: 99%

Superconducting bearings

Hull

2000

Supercond. Sci. Technol.

469

203

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The physics and technology of superconducting bearings is reviewed. Particular attention is given to the use of high-temperature superconductors (HTSs) in rotating bearings. The basic phenomenology of levitational forces is presented, followed by a brief discussion of the theoretical models that can be used for conceptual understanding and calculations. The merits of various HTS bearing designs are presented, and the behaviour of HTS bearings in typical situations is discussed. The article concludes with a brief survey of various proposed applications for HTS bearings.

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“…19, a systematic treatment of vertical levitation force for type-II superconductors based on flux penetration was done. Some papers 20,21 have considered granular structure for the superconductors when grains are completely penetrated.…”

Section: Introductionmentioning

confidence: 99%

Magnetic levitation of superconductors in the critical state

Navau

Sanchez

1998

Phys. Rev. B

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The vertical levitation force in a cylindrically symmetric system composed of a permanent magnet and a type-II superconductor is studied assuming the latter to be in a critical state. In a first step, a constant-fieldgradient approximation along the length of the superconductor is used to see the effects of the dependence of the critical current density on the internal magnetic field. In a second step, the theory is generalized in order to study the case when the field gradient is not constant, as is usually found in levitation experiments with bulk superconducting samples. The model results are discussed in relation to recent experimental data on magnetic levitation of high-T c superconductors, explaining the observed behavior and making some predictions for future experiments. ͓S0163-1829͑98͒00426-3͔

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Measurements and model calculations of forces betpeen a magnet and granular high-Tc superconductor

Cited by 12 publications

References 15 publications

Calculation of the hysteretic force between a superconductor and a magnet

Calculation of the hysteretic force between a superconductor and a magnet

Superconducting bearings

Magnetic levitation of superconductors in the critical state

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