Spin-stabilized magnetic levitation is a

phenomenon A phenomenon ( : phenomena) is an observable event. The term came into its modern philosophical usage through Immanuel Kant, who contrasted it with the noumenon, which ''cannot'' be directly observed. Kant was heavily influenced by Gottfried ...

magnetic levitation Magnetic levitation (maglev) or magnetic suspension is a method by which an object is suspended with no support other than magnetic fields. Magnetic force is used to counteract the effects of the gravitational force and any other forces. The ...

whereby a spinning magnet or array of magnets (typically as a top) is levitated via magnetic forces above another magnet or array of magnets, and stabilised by gyroscopic effect due to a spin that is neither too fast, nor too slow to allow for a necessary

precession Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the first Euler angle, whereas the third Euler angle defines the rotation itself. In oth ...

. The phenomenon was originally discovered through invention by

Vermont Vermont () is a state in the northeast New England region of the United States. Vermont is bordered by the states of Massachusetts to the south, New Hampshire to the east, and New York to the west, and the Canadian province of Quebec to ...

inventor Roy M. Harrigan in the 1970s. On May 3, 1983 Harrigan received a United States patent for his original levitation device based upon this phenomenon he discovered. Independent of Harrigan, a Pennsylvanian inventor named Joseph Chieffo made the same discovery in 1984 employing a flat base magnet, a geometry that proved a significant change over his predecessor's design which relied upon a dish shaped mounting of magnets for the base. Chieffo's design, publicized in a 1991 edition of the periodical "MAGNETS IN YOUR FUTURE", further differed from Harrigan's in its incorporation of an un-weighted top.Alt URL
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/ref> Harrigan's technology, either entirely or in conjunction with Chieffo's flat-base innovation, provided the basis for the development of a

mass market The term "mass market" refers to a market for goods produced on a large scale for a significant number of end consumers. The mass market differs from the niche market in that the former focuses on consumers with a wide variety of backgrounds wi ...

ed levitating toy top sold under the brand name, ' Levitron'. In 2012 and 2014 Max Michaelis reported operating Levitron brand magnetic tops at inclination angles of 45° and 90° (i.e. with the spin axis, horizontal) after employing novel configurations for the supporting magnetic fields.

Physics

Earnshaw's theorem does not allow for a static configuration of

permanent magnets A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, steel, nickel, ...

to stably levitate another permanent magnet or materials that are

paramagnetic Paramagnetism is a form of magnetism whereby some materials are weakly attracted by an externally applied magnetic field, and form internal, induced magnetic fields in the direction of the applied magnetic field. In contrast with this behavior, ...

or ferromagnetic against

gravity In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the stro ...

. This theorem does not apply to devices consisting of a properly configured magnetic base and corresponding magnetic top, however, because the non-static nature of the spinning top acts as a gyroscope to prevent its magnetic field from fully aligning itself in the same direction as that of the primary supporting toroidal field of the magnetic base (i.e.: via the top flipping). In a vertical orientated configuration this gyroscopic property combined with the top's

allows it to respond dynamically to the direction of the local

toroid In mathematics, a toroid is a surface of revolution with a hole in the middle. The axis of revolution passes through the hole and so does not intersect the surface. For example, when a rectangle is rotated around an axis parallel to one of its ...

ally shaped field of its base magnet(s) and remain levitating about a central point in space above the base where the forces acting on the top (gravitational, magnetic, and gyroscopic) are in equilibrium thereby allowing the top to rest in an energy minimum well. (see:

) In the laboratory, experimental setups are able to levitate tops for indefinite periods by measuring the spin rate and maintaining it using a drive coil. However, variations in temperature can affect the stability, and without ambient temperature control the top will eventually fall after hours or days due to the

temperature coefficient A temperature coefficient describes the relative change of a physical property that is associated with a given change in temperature. For a property ''R'' that changes when the temperature changes by ''dT'', the temperature coefficient α is def ...

of the magnets. The physics of the magnetic stability is similar to magnetic gradient traps. Inclined or horizontal axis levitation is accomplished by superposing a “macro-trap” on the precessional “micro-trap” first described by Sir Michael Berry and Simon, Heflinger and Ridgway. The macro-trap is generated by a combination of two magnetic “V”s as well as a puller magnet, situated directly above the Levitron. The puller acts like the string of a pendulum.

References

{{Reflist Magnetic levitation Articles containing video clips Tops

Physics

See also

References