Spin stabilized magnetic levitation
Encyclopedia
Spin-stabilized magnetic levitation is a phenomenon
of magnetic levitation
where a magnet 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.
The phenomenon was originally discovered through invention
by Vermont
inventor Roy M. Harrigan in the late 1970s. A Delaware
inventor named Joseph Chieffo who was not previously aware of Harrigan's invention made the same discovery in 1984 (using a somewhat different device configuration from Harrigan's). Harrigan received a United States patent
for his original levitation device based upon this phenomenon on May 3, 1983. A spin-stabilized magnetic levitation device entirely based upon Harrigan's discovery is marketed as a science toy under the trademark brand name, 'Levitron
'.
does not allow for a static configuration of permanent magnets to stably levitate another permanent magnet or materials that are paramagnetic
or ferromagnetic
against gravity
. This theorem does not apply to devices consisting of a properly configured magnetic base and corresponding top, however, because the non-static nature of the spinning top acts as a gyroscope
to prevent its magnetic field
from aligning itself in the same direction as that of the primary field of the magnetic base (i.e.: via the top flipping). This gyroscopic property combined with the top's precession
allows it to respond dynamically to the direction of the local toroid
ally shaped field of its base magnet 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 minima
well. (see: magnetic levitation)
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 of the magnets.
The physics of the magnetic stability is similar to magnetic gradient trap
s.
Phenomenon
A phenomenon , plural phenomena, is any observable occurrence. Phenomena are often, but not always, understood as 'appearances' or 'experiences'...
of magnetic levitation
Magnetic levitation
Magnetic levitation, maglev, or magnetic suspension is a method by which an object is suspended with no support other than magnetic fields...
where a magnet 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.
The phenomenon was originally discovered through invention
Invention
An invention is a novel composition, device, or process. An invention may be derived from a pre-existing model or idea, or it could be independently conceived, in which case it may be a radical breakthrough. In addition, there is cultural invention, which is an innovative set of useful social...
by Vermont
Vermont
Vermont is a state in the New England region of the northeastern United States of America. The state ranks 43rd in land area, , and 45th in total area. Its population according to the 2010 census, 630,337, is the second smallest in the country, larger only than Wyoming. It is the only New England...
inventor Roy M. Harrigan in the late 1970s. A Delaware
Delaware
Delaware is a U.S. state located on the Atlantic Coast in the Mid-Atlantic region of the United States. It is bordered to the south and west by Maryland, and to the north by Pennsylvania...
inventor named Joseph Chieffo who was not previously aware of Harrigan's invention made the same discovery in 1984 (using a somewhat different device configuration from Harrigan's). Harrigan received a United States patent
United States Patent and Trademark Office
The United States Patent and Trademark Office is an agency in the United States Department of Commerce that issues patents to inventors and businesses for their inventions, and trademark registration for product and intellectual property identification.The USPTO is based in Alexandria, Virginia,...
for his original levitation device based upon this phenomenon on May 3, 1983. A spin-stabilized magnetic levitation device entirely based upon Harrigan's discovery is marketed as a science toy under the trademark brand name, 'Levitron
Levitron
Levitron is a brand of levitating toys and gifts in science and educational markets marketed by Creative Gifts Inc. and Fascination Toys & Gifts. The Levitron top device is a commercial toy that displays the phenomenon known as spin stabilized magnetic levitation...
'.
Physics
Earnshaw's theoremEarnshaw'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 Earnshaw in 1842. It is usually referenced to magnetic...
does not allow for a static configuration of permanent magnets to stably levitate another permanent magnet or materials that are paramagnetic
Paramagnetism
Paramagnetism is a form of magnetism whereby the paramagnetic material is only attracted when in the presence of an externally applied magnetic field. In contrast with this, diamagnetic materials are repulsive when placed in a magnetic field...
or ferromagnetic
Ferromagnetism
Ferromagnetism is the basic mechanism by which certain materials form permanent magnets, or are attracted to magnets. In physics, several different types of magnetism are distinguished...
against gravity
Gravitation
Gravitation, or gravity, is a natural phenomenon by which physical bodies attract with a force proportional to their mass. Gravitation is most familiar as the agent that gives weight to objects with mass and causes them to fall to the ground when dropped...
. This theorem does not apply to devices consisting of a properly configured magnetic base and corresponding top, however, because the non-static nature of the spinning top acts as a gyroscope
Gyroscope
A gyroscope is a device for measuring or maintaining orientation, based on the principles of angular momentum. In essence, a mechanical gyroscope is a spinning wheel or disk whose axle is free to take any orientation...
to prevent its magnetic field
Magnetic field
A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...
from aligning itself in the same direction as that of the primary field of the magnetic base (i.e.: via the top flipping). This gyroscopic property combined with the top's precession
Precession
Precession is a change in the orientation of the rotation axis of a rotating body. It can be defined as a change in direction of the rotation axis in which the second Euler angle is constant...
allows it to respond dynamically to the direction of the local toroid
Torus
In geometry, a torus is a surface of revolution generated by revolving a circle in three dimensional space about an axis coplanar with the circle...
ally shaped field of its base magnet 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 minima
Minimum total potential energy principle
The principle of minimum total potential energy is a fundamental concept used in physics, chemistry, biology, and engineering. It asserts that a structure or body shall deform or displace to a position that minimizes the total potential energy, with the lost potential energy being dissipated as heat...
well. (see: magnetic levitation)
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 of the magnets.
The physics of the magnetic stability is similar to magnetic gradient trap
Magnetic trap (atoms)
A magnetic trap uses a magnetic gradient to trap neutral particles with a magnetic moment. Although such traps have been employed for many purposes in physics research, they are best known as the last stage in cooling atoms to achieve Bose-Einstein condensation...
s.