Whence such strange behavior?
From the structure of the material. Atoms and molecules do not get magnetized individually, but they affect their neighbors in whole regions or "domains." In normal metals with their regular, crystalline structure, an entire such domain gets magnetized; no individual dis-sidents are tolerated, much like in academic freedom at Dartmouth and elsewhere.
It is also much like the domino theory: not because one domino causes the others to fall, but because once they have fallen (repre-senting magnetized atoms), you cannot lift the last domino by itself and make it fall the other way: all the other dominoes will have to be lifted and made to fall the other way also.
But to flip the whole row of dominoes takes work, a lot more than if each were free to be flipped individually on a ball bearing unobstructed by its neighbor. Quite similarly, it takes work to re-magnetize an entire domain
¾more than it would take to re-magnetize its constituent atoms individually. In fact the work performed in one cycle is proportional to the area of the hysteresis loop, and that is done 60 times each second in all the transformers in the country.The work done in overcoming hysteresis appears as heat, which is part of the reason why large power transformers are submerged in coolant. This heat is a waste of energy, which until recently seemed inevitable.
Why? Because hysteresis is caused by the magnetic domains, and they, in turn, are caused by the crystalline structure of metals (which bonds atoms together in a grid). One could use a material with its molecules arranged irregularly, at random
¾an "amor-phous" material such as glass or air. This will totally remove the hysteresis¾but only like beheading will totally remove a head-ache, for all the magnetic advantages disappear along with the hys-teresis.What is needed is a material as amorphous as glass, yet as con-ductive and magnetic as iron, so we can have the best of both worlds. Such glassy metals ("glasmets," trade name "Metglas") have been around for the last 15 years or so and are produced by melting the metal so that it loses its crystalline structure and then cooling it so rapidly (1 million degrees C per sec) that it solidifies (into ribbons moving at 60 mph) without getting a chance to rebuild its crystals.
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Vol. 16, No. 4
Newsletter: Access to Energy Newsletter Archive Volume: Issues Issue/No.: Vol. 16, No. 4 Date: December 01, 2004 02:14 PM Title: Subsidizing science
Copyright © 2004 - Access to Energy Newsletter Archive
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