University of Houston physicists¹ report finding major theoretical flaws in the generally accepted understanding of how a superconductor traps and holds a magnetic field. More than 50 years ago, C.P. Bean, a scientist at General Electric, developed a theoretical explanation known as the "Bean Model" or "Critical State Model." The basic property of superconductors is that they represent zero "resistance" to electrical circuits. In a way, they are the opposite of toasters, which resist electrical currents and thereby² convert energy into heat. Superconductors consume zero energy and can store it for a long period of time. Those that store magnetic energy --known as "trapped field magnets" or TFMs -- can behave like a magnet.

 

In the Journal of Applied³ Physics, from AIP Publishing, the researchers describe experiments whose results exhibited "significant deviations⁴" from those of the Critical State Model. They revealed unexpected new behavior favorable to practical applications, including the possibility of using TFMs in myriad⁵ new ways.

 

Much of modern technology is already based on magnets. "Without magnets, we'd lack generators⁶ [electric lights and toasters], motors [municipal water supplies, ship engines], magnetrons [microwave ovens], and much more," said Roy Weinstein, lead author of the study, and professor of physics emeritus⁷ and research professor at the University of Houston.

 

Generally, the performance of a device based on magnets improves as the strength of the magnet increases, up to the square of the increase. In other words, if a magnet is 25 times stronger, the device's performance can range from 25 to 625 times better.

 

TFMs are clearly intriguing⁸, but their use has been largely held back by the challenge of getting the magnetic field into the superconductor. "A more tractable⁹ problem is the need to cool the superconductor to the low temperature at which it superconducts," Weinstein explained.

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