It is one of the most versatile and formidable new technologies in existence. Its applications range from the manufacture of blazingly fast passenger trains to the development of specialized bombs with the potential to obliterate an enemy's firepower using methods formerly exclusive to the realm of science fiction. Superconductivity not only has the potential to fill the most impatient individual's need for speed but could also save lives.
A superconductor is a substance that, when cooled below some critical temperature, will allow electric current to flow without resistance. Under the right conditions, this current will flow for an unlimited amount of time in a closed circuit'a real-life example of a perpetual motion machine.
Superconductors can be divided into two categories. Type I superconductors are metals that superconduct at up to about 72 degrees Kelvin and therefore have to be chilled at the coldest possible temperatures to function. Type II superconductors work at up to 138 K; heated copper oxides used in the manufacture of electromagnets fall into this category.
The discovery of superconductors dates back to 1911 when Nobel Prize-winning physicist Heike Kammerlingh Onnes discovered that mercury chilled to 4 K had no resistance to electricity. Twenty-two years later, Walter Meissner and Robert Ochsenfeld found that superconductors have the ability to disrupt magnetism. Magnetic fields induce a flow of current in normal conductors; in superconductors the currents oppose the normal magnetic attraction, a force so intense the magnet can hover indefinitely over the superconductor. This is commonly labeled the Meissner effect or diamagnetism.
During the 1940s and '50s, various substances were tested for superconductivity at increasingly higher temperatures. Niobium nitride's critical temperature was 16 K, while vanadium-silicon compounds started to superconduct when a degree and a half warmer.
In 1962, Brian D. Josephson correctly hypothesized that an electric field would run between two superconductors if that space was shared with a nonsuperconductor. Today this 'Josephson effect' is the principle behind an instrument called a SQUID (superconducting quantum interference device), which measures miniscule magnetic fields.
The 1980s witnessed the rise of 'designer molecules''molecules that behave in a fairly uniform way. By 1986, the record highest critical temperature was 30 K, in a ceramic copper oxide. This was a revelation, as it shattered earlier assumptions that ceramics are incapable of transmitting electricity. It was later discovered that the addition of lead to the substance raised the critical temperature to a comparatively sizzling 58 K.
As mentioned earlier, superconductivity has a wide range of applications. The Meissner effect has been used to make trains that float above superconducting magnets to obliterate friction that inhibits the trains from achieving high speeds. These maglev (magnetic levitation) trains are so expensive to maintain that they were only used as a means of public transportation on a regular basis in Birmingham, England for 11 years and on an experimental basis in Japan where the trains have reached speeds of up to 343 miles per hour. A German maglev line is slated to open in 2006.
A more practical application would be the creation of more powerful MRI scanners in which it is possible to enhance the magnetic field for a sharper image. This allows doctors to accurately study disease by sending a magnetic field into the body that makes hydrogen atoms project energy that efficiently translates into valuable data on a computer screen.
Superconductivity has also changed the way power is stored and transmitted. In the past transformers were not only filled with flammable oil and protected with barbed wire, but there was always the risk of an energy loss between the power plant and the service recipient. Superconductor-based transformers are more efficient because much less current is lost, and safer because they are chilled in liquid nitrogen and housed in buildings. One of these transformers is currently being constructed in Waukesha, Wis.
At UW-Madison, research in the field is mainly centered on biomedical, physics, and computer science applications. For example, Professor David Larbalestier, of the Department of Materials Science and Engineering, is working on an accelerator that will be used in advanced particle physics experiments. His project closely resembles one getting under way in Geneva, Switzerland, in which physicists are trying to construct a 30-kilometer ring to guide particles into collisions and come up with a universal theory on the nature of matter.
The future of superconductivity is currently centered on its military potential which lies in the manufacture and deployment of electromagnetic bombs. The first E-bomb test is slated to take place next year. Though the Army would eventually like to see them used for detonating artillery shells in midair, current plans call for the bombs to be stored in Air Force bombers, unmanned aerial vehicles, strike fighters and cruise missiles. Jim Wilson of Popular Mechanics remarked on the advanced level of science that went into creating the bombs.
'When fielded, these will be the most technologically superior weapons the U.S. military establishment have ever built,' Wilson said.
E-bombs are composed of an explosive-filled tube within a copper coil. The second before they explode, a magnetic field is generated by a bank of capacitors. The tube shoots out from the back, brushing against the coil, creating a mobile short circuit. The resulting pulse has been said to 'make a lightning bolt seem like a flashbulb by comparison.'
However, some fear that because a variation of the E-bomb can be cheaply made with comparatively primitive technology, terrorists could create weapons just as potent, a fact on which many working on America's E-bombs are hesitant to elaborate. One can only hope that the use of superconductivity for military purposes is limited and that more attention is given to using the technology to enhance and protect human life.
