superconductivity and maglev trains

Topics: Superconductivity, Superconducting magnet, BCS theory Pages: 5 (1506 words) Published: May 28, 2014
What is so super about superconductors? Perhaps the fact that superconductors are materials that have no resistance to the flow of electricity. So they basically will conduct electricity without resistance when the material is at a very cool temperature. Resistance becomes undesirable because it produces losses in the energy flowing through the material. Resistance creates heat which is why, when the material is cooled, the resistance will no longer be an included factor in the flow of electricity. Due to there being no resistance that means there is no loss in energy. Superconductivity creates much more energy than a normal conductor. If a current can be superconducting its flow of electricity will remain continuous.

There are 2 types of Superconductors: Type I and Type II. Type I Superconductors are made from pure metals. Type I has a zero electricity resistivity, zero magnetic field, and critical magnetic field above which superconductivity stops. (hyperphysics) Type I Superconductors are often referred to as “soft” superconductors because they have been limited in practical usage. Type II superconductors are made from alloys. They exhibit much higher critical magnetic fields than Type I and for this are noted as the “hard” superconductor. Also all high temperature superconductors fall under Type II. Type II superconductors are able to sustain superconductivity in the presence of much higher magnetic fields. The real difference between the two superconductors is the way in which they revert to normal conductivity in the presence of a critical field. It can then be said that Type II is more commonly used because it is “stronger”. All superconducting magnets used in high-field research are Type II.

In 1908, a Dutch physicist named Heike Kamerlingh Onnes liquefied Helium. By doing this he achieved lowering the temperature to about 1.5 K, this was the coldest temperature seen on Earth! Following this achievement, in 1911 Onnes found that a solid Mercury wire immersed in liquid helium brought the wire’s resistance to zero. He stated on his discovery that, “Mercury has passed into a new state, which on account of its extraordinary properties may be called the superconductive state”. (wiki) The next step in understanding the concept of superconductivity came in 1933 when 2 German researchers, Meissner and Ochsenfeld, discovered that superconducting materials will repel magnetic fields. The induced currents in a superconductor will mirror the field that would’ve initially penetrated the superconducting material (which repulses the magnet) This idea is referred to as the Meissner Effect or ”strong diamagnetism”.

Scientists today have been working ruthlessly to put this effect into use in the real world today. In Japan the Japanese Railway Technical Research Institute have been able to integrate this technology in order to create magnetic levitating trains otherwise known as Maglev trains. Maglev trains combine the use of superconducting coils in order to make the weight of the train float above a charged track. Running on tracks that are surrounded in liquid nitrogen allows the metal to reach a level cold enough to make the metal superconductive. Once the metal is made super conductive the magnet strips underneath the train have magnetic fields that match up with the track. This matching of magnetic fields somewhat glues the train into position onto the track and allows it to float in alignment above the track.

In Maglev trains there are two different types of superconducting coils. One is calls propulsions coils and another is called levitating coils. The purpose of the propulsion coils is to have a flow of energy within the track that makes the train move. The propulsion coils send a surge of energy upstream which attract the train and then they send a current of energy downstream to then push the train. The pushing and pulling forces allow the train to move by the impulses of...
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