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. Magnetic pressure is used to counteract the effects of the gravitational and any other accelerations.


Magnetic levitation is used for maglev trains, magnetic bearings and for product display purposes.
Earnshaw's theorem proves that using only ferromagnetic or paramagnetic materials it is impossible to stably levitate against gravity, but servomechanisms, the use of diamagnetic materials, superconduction, or systems involving eddy currents permit this to occur.


In some cases the lifting force is provided by magnetic levitation, but there is a mechanical support bearing little load that provides stability. This is termed pseudo-levitation.


  


TIME LINE

1839
Earnshaw's theorem showed electrostatic levitation was impossible,   later theorem was extended to magnetostatic levitation by others


1912
 Emile Bachelet awarded a patent in March 1912 for his “levitating
 transmitting apparatus” (patent no. 1,020,942) for electromagnetic
 suspension system


1933
Superdiamagnetism Walter Meissner and Robert Ochsenfeld (the Meissner effect)


1934
Hermann Kemper “monorail vehicle with no wheels attached.” Reich Patent number 643316


1939
Braunbeck’s extension showed that magnetic levitation is possible with diamagnetic materials


1939
Bedford, Peer, and Tonks aluminum plate placed on two concentric cylindrical coils shows 6-axis stable levitation.


1961
James R. Powell and BNL colleague Gordon Danby electrodynamic levitation using superconducting magnets


1970s
Spin stabilized magnetic levitation Roy M. Harrigan


1974
Magnetic river Eric Laithwaite and others

1979 
transrapid train carried passengers


1984
Low speed maglev shuttle in Birmingham Eric Laithwaite and others


1997
Diamagnetically levitated live frog Andre Geim


1999
Inductrack permanent magnet electrodynamic levitation (General Atomics)


2005
homopolar electrodynamic bearing

USES 

MAGLEV TRANSPORTATION

Maglev, or magnetic levitation, is a system of transportation that suspends, guides and propels vehicles, predominantly trains, using magnetic levitation from a very large number of magnets for lift and propulsion. This method has the potential to be faster, quieter and smoother than wheeled mass transitsystems. The technology has the potential to exceed 6,400 km/h (4,000 mi/h) if deployed in an evacuated tunnel. If not deployed in an evacuated tube the power needed for levitation is usually not a particularly large percentage and most of the power needed is used to overcome air drag, as with any other high speed train.

The highest recorded speed of a maglev train is 581 kilometers per hour (361 mph), achieved in Japan in 2003, 6 km/h faster than the conventional TGV speed record.

                                     A magnetic levitation passenger train on the test track

MAGNETIC BEARINGS

• Magnetic bearings

                   

• Flywheels

                     

• Centrifuges

                   

                        Small bench centrifuges

• Magnetic ring spinning

             

Magnetic levitation, a spinning magnet over a stationary ring magnet.