Spin-stabilized magnetic levitation is a phenomenon of

magnetic levitation Magnetic levitation (maglev) or magnetic suspension is a method by which an object is levitation (physics), suspended with no support other than magnetic fields. Lorentz force, Magnetic force is used to counteract the effects of the gravitation ...

whereby a spinning magnet or array of magnets (typically as a

top Top most commonly refers to: * Top, a basic term of orientation, distinguished from bottom, front, back, and sides * Spinning top, a ubiquitous traditional toy * Top (clothing), clothing designed to be worn over the torso * Mountain top, a moun ...

) is levitated via magnetic forces above another magnet or array of magnets, and stabilised by gyroscopic effect due to a spin rate 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 o ...

. The phenomenon was originally discovered through

invention An invention is a unique or novelty (patent), novel machine, device, Method_(patent), method, composition, idea, or process. An invention may be an improvement upon a machine, product, or process for increasing efficiency or lowering cost. It m ...

Vermont Vermont () is a U.S. state, state in the New England region of the Northeastern United States. It borders Massachusetts to the south, New Hampshire to the east, New York (state), New York to the west, and the Provinces and territories of Ca ...

inventor Roy M. Harrigan in the 1970s. On May 3, 1983, Harrigan was granted a

US patent Under United States law, a patent is a right granted to the inventor of a (1) process, machine, article of manufacture, or composition of matter, (2) that is new, useful, and non-obvious. A patent is the right to exclude others, for a limit ...

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 patented design which relies 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 solely or in conjunction with Chieffo's published flat-base variation, provided the basis for the development of a series of

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 with ...

ed levitating toy tops sold predominantly in the United States under the brand name, ' Levitron' and in other countries from different manufacturers under their brand names (e.g. UCAS in Japan). 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 field A magnetic field (sometimes called B-field) is a physical field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular ...

Physics

Earnshaw's theorem Earnshaw's theorem states that a collection of point charges cannot be maintained in a stable stationary equilibrium configuration solely by the electrostatic interaction of the charges. This was first proven by British mathematician Samuel Earns ...

does not allow for a static configuration of

permanent magnets Permanent may refer to: Art and entertainment * ''Permanent'' (film), a 2017 American film * ''Permanent'' (Joy Division album) * "Permanent" (song), by David Cook *"Permanent", a song by Alex Lahey from '' The Answer Is Always Yes'', 2023 Other ...

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, ...

ferromagnetic Ferromagnetism is a property of certain materials (such as iron) that results in a significant, observable magnetic permeability, and in many cases, a significant magnetic coercivity, allowing the material to form a permanent magnet. Ferromagne ...

against gravity. This theorem does not apply to devices consisting of a properly configured axially magnetized magnetic base and corresponding axially magnetized magnetic top, however, because the non-static nature of the spinning magnetic top within a threshold of lower and upper

RPM Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or r⋅min−1) is a unit of rotational speed (or rotational frequency) for rotating machines. One revolution per minute is equivalent to hertz. Standards ISO 80000-3:2019 def ...

spin rates acts as a balanced precessing

gyroscope A gyroscope (from Ancient Greek γῦρος ''gŷros'', "round" and σκοπέω ''skopéō'', "to look") is a device used for measuring or maintaining Orientation (geometry), orientation and angular velocity. It is a spinning wheel or disc in ...

to prevent the poles of its

from fully aligning themselves in the same direction as those of the primary supporting toroidal field of the magnetic base (i.e.: via the top flipping). In a vertical orientated spin axis configuration this gyroscopic property with its necessary precession allows the top to keep its field in an oppositional orientation by responding dynamically to the field direction of the central magnetic field

gradient In vector calculus, the gradient of a scalar-valued differentiable function f of several variables is the vector field (or vector-valued function) \nabla f whose value at a point p gives the direction and the rate of fastest increase. The g ...

of the

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) with the base gradient decreasing radially towards the central interior of the base field and thereby remain self-centered in a restorative manner, levitating about an elevated central point within the base magnetic field where the forces acting on the top (

gravitational In physics, gravity (), also known as gravitation or a gravitational interaction, is a fundamental interaction, a mutual attraction between all massive particles. On Earth, gravity takes a slightly different meaning: the observed force be ...

, magnetic, and gyroscopic) are in a stable

equilibrium Equilibrium may refer to: Film and television * ''Equilibrium'' (film), a 2002 science fiction film * '' The Story of Three Loves'', also known as ''Equilibrium'', a 1953 romantic anthology film * "Equilibrium" (''seaQuest 2032'') * ''Equilibr ...

thus allowing the top to stay hovering while resting 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 spin 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 Spinning tops

Physics

See also

References