Magnetic Flux Lines

• All magnetic objects produce invisible lines of force that extend between the poles.

Meissner Effect/Perfect Diamagnetism

• Magnetic field lines penetrate most objects.

• However, below their Tcand Hc , superconducting materials exclude field lines (flux).

Crystal Lattice

• There are often imperfections in the

superconductor’s lattice structure.

• YBCO crystal lattice structure

How Maglev Works

Support System

•The electromagnets on the underside of the train pull it up to the ferromagnetic stators on the track and levitate the train.

•The magnets on the side keep the train from moving from side to side.

•A computer changes the amount of current to keep the train 1 cm from the track.

Maglev is short for magnetic levitation, which means that these trains will float over a guideway using the basic principles of magnets to replace the old steel wheel and track trains.

This means there is no friction between the train and the track!

There are three components to this system:A large electrical power sourceMetal coils lining a guideway or trackLarge guidance magnets attached to the underside of the train

Transrapid 09 at the Emsland test facility in Germany

Levitation System’s Power Supply• . Electromagnets are similar to other magnets in

that they attract metal objects, but the magnetic pull is temporary.

• The batteries can levitate the train for 30 minutes without any additional energy.

• Linear generators in the magnets on board the train use the motion of the train to recharge the batteries.

• Levitation system uses less power than the trains air conditioning.

Propulsion System•The system consists of aluminum three-phase cable windings in the stator packs that are on the guideway

•When a current is supplied to the windings, it creates a traveling alternating current that propels the train forward by pushing and pulling.

•When the alternating current is reversed, the train brakes.

•Different speeds are achieved by varying the intensity of the current.•Only the section of track where the train is traveling is electrified.

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How it WorksType of Magnet Uses

•This train uses superconducting electric magnets in the vehicle to levitate and propel the train. These magnets are cooled by liquid helium or liquid nitrogen. This means that once electrified these magnets do not require additional energy.

Propulsion

•An alternating current is ran through electromagnet coils on the guide walls of the guide way. This creates a magnetic field that attracts and repels the superconducting magnets on the train and propels the train forward.

•Braking is accomplished by sending an alternating current in the reverse direction so that it is slowed by attractive and repulsive forces.

Levitation •The passing of the superconducting magnets by figure eight levitation coils on the side of the tract induces a current in the coils and creates a magnetic field. This pushes the train upward so that it can levitate 10 cm above the track.

•The train does not levitate until it reaches 50 mph, so it is equipped with retractable wheels.

Lateral Guidance

•When one side of the train nears the side of the guideway, the super conducting magnet on the train induces a repulsive force from the levitation coils on the side closer to the train and an attractive force from the coils on the farther side. This keeps the train in the center.

Summary

• Maglev trains use magnets to levitate and propel the trains forward.

• Since there is no friction these trains can reach high speeds.

• It is a safe and efficient way to travel.

• Governments have mixed feelings about the technology. Some countries, like China, have embraced it and others like Germany have balked at the expense.

III . The Future

Maglev Trains

• Room temperature superconducting magnets

• Generating energy at faster speeds using less energy at lower cost

NASA

• Maglev technology could give space vehicles a “running start” to break from Earth’s gravity.

Maglev Space Propulsion

• Launching systems would use magnetic fields to levitate and accelerate a vehicle along a track .

• Reaching the end of the track, the vehicle could switch to more conventional rocket engines.

Advantages….

• High speed..

• Low friction

• No pollution

• Maglev systems are energy efficient

• avoid excessive vibrations

Aman AnandDSCESEM- 6th sec- A