A Self Rotating Magnet Levitating Above a YBCO Specimen

Martini, G.; Rivetti, A.; Pavese, Franco

doi:10.1007/978-1-4613-0639-9_75

Cited by 6 publications

(9 citation statements)

References 1 publication

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“…In agreement with previous work [2,3] we find that the tendency to spinning is strongest when the magnet is situated in a region of large temperature gradient. In the setup of Fig.…”

Section: Pacs Numberssupporting

confidence: 93%

“…We have found this by experimentation with 8 different magnets, some with a high degree of homogeneity and some with less. The torque that makes the magnet oscillate and spin is to lowest order proportional to the magnet's angular velocity: if the magnet is initially at rest with zero angular velocity it is in unstable equilibrium, and any small perturbation will initiate the motion .In agreement with previous work [2,3] we find that the tendency to spinning is strongest when the magnet is situated in a region of large temperature gradient. In the setup of Fig.…”

supporting

confidence: 90%

“…However it appears not to be widely known that under appropriate conditions a levitating magnet has a strong tendency to start spinning: independent of initial conditions the rotation will reach a terminal velocity and persist, overcoming resistance due to air friction. After coming across this phenomenon independently we found out that this remarkable effect has been seen and discussed before [2,3]. However its physical origin has not been completely elucidated before.…”

mentioning

confidence: 86%

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Spontaneous spinning of a magnet levitating over a superconductor

Hirsch

Hirsch²

2003

Physica C: Superconductivity

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“…In agreement with previous work [2,3] we find that the tendency to spinning is strongest when the magnet is situated in a region of large temperature gradient. In the setup of Fig.…”

Section: Pacs Numberssupporting

confidence: 93%

supporting

confidence: 90%

mentioning

confidence: 86%

See 1 more Smart Citation

Spontaneous spinning of a magnet levitating over a superconductor

Hirsch

Hirsch²

2003

Physica C: Superconductivity

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“…A phenomenon related to bearing dynamics is the possibility for self-oscillation that may lead to rotation of a PM disc initially levitated without motion over a HTS [29,139,140]. The cause of the phenomenon appears to be a temperature gradient across the PM, in which the temperature dependence of the magnetization causes the centre of levitation force to reside below the centre of gravity, a situation that is mechanically unstable.…”

Section: Bearing Dynamicsmentioning

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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“…Experiments show that the cylindrical magnet starts to oscillate around its horizontal axis with increasing amplitude and will eventually rotate continuously with a nearly constant angular speed. The effect was explained independently in [5], [7], and [10] (see also [9]). The energy for the rotation is due to temperature differences of the surrounding air.…”

Section: Introductionmentioning

confidence: 99%

The dynamics of a levitated cylindrical permanent magnet above a superconductor

Schreiner¹

2003

Rev. Mat. Complut.

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When a permanent magnet is released above a superconductor, it is levitated. This is due to the Meissner-effect, i.e. the repulsion of external magnetic fields within the superconductor. In experiments, an interesting behavior of the levitated magnet can be observed: it might start to oscillate with increasing amplitude and some magnets even reach a continuous rotation. In this paper we develop a mathematical model for this effect and identify by analytical methods as well with finite element simulations two reasons for the described behavior of the levitated magnet. It is shown, that the oscillations of the magnet are due to inhomogeneities of the magnetization within the magnet, whereas the continuous rotations are due to temperature gradients of the surrounding air.

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A Self Rotating Magnet Levitating Above a YBCO Specimen

Cited by 6 publications

References 1 publication

Spontaneous spinning of a magnet levitating over a superconductor

Spontaneous spinning of a magnet levitating over a superconductor

Superconducting bearings

The dynamics of a levitated cylindrical permanent magnet above a superconductor

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