Trains, magnetically levitated, superconductors

The discovery of high-temperature superconductors is surely one of the most exciting scientific developments in the last 20 years. It has stimulated an enormous amount of research in chemistry, physics, and materials science that could some day lead to a world of superfast computers, magnetically levitated trains, and power lines that carry electric current without loss of energy. 

Potential applications of superconductors include electrical transmission (little or no heat loss in wires) and energy-efficient transportation (magnetically levitated trains, etc ). 

FIGURE 3.43 High-temperature superconductors may make magnetically levitated vehicles a reality. This picture shows an experimental train in Japan. 

Superconductors have been applied to develop train systems that operate with magnetic-levitation (MAGLEV) in which the train effectively travels sslOmm above its tracks, i.e. virtually frictionless motion. The first commercial train came into service in Shanghai in 2003 and can reach speeds of 440 km h. ... 

Figure 12.37 The levitating power of a superconducting oxide. A magnet is suspended above a cooled high-temperature superconductor. Someday, this phenomenon may be used to levitate trains above their tracks for quiet, fast travel.

In the 1980s, a ceramic form of copper(I) oxide was found to have superconducting properties at temperatures higher than previously known superconductors. Superconductors have the ability to carry an electric current virtually without resistance. Once a current is initiated in a superconductor, it continues to travel through the material essentially forever. Superconductor research may lead to new technologies, from cheaper electrical power to magnetically levitated high-speed trains. 

Superconductors have the ability to levitate vehicles with embedded magnets. This picture shows an experimental zero-friction train in Japan, built to use helium-cooled metal superconductors. 

An interesting property of superconductors is their ability to create a mirror image of a magnetic field within themselves. As a result, they are repelled by magnetic fields and can even be levitated above them (see Fig. 1.53). This property has led to research on the possibility of levitating railroad trains and other vehicles fitted with superconductors over magnetic tracks (see Fig. 3.43). 

There is good reason to be enthusiastic about these materials. Because liquid nitrogen is quite cheap (a liter of liquid nitrogen costs less than a liter of milk), we can envision electrical power being transmitted over hundreds of miles with no loss of energy. The levitation effect can be used to construct fast, quiet trains that glide over (but are not in contact with) the tracks. Superconductors can also be used to build superfast computers, called supercomputers, whose speeds are limited by how fast electric current flows. Furthermore, the enormous magnetic fields that can be created in superconductors will result in more powerful particle accelerators, efficient devices for nuclear fusion, and... 

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