Building World-Record Magnets; June 1995; Scientific American Magazine; by Boebinger, Passner, Bevk; 7 Page(s)
December 3, 1992, began routinely enough. For several months we had been studying how an intense magnetic field nullifies superconductivity--the complete absence of electrical resistance in certain materials. Our high-strength electromagnet, designed and built 11 months earlier, had generated thousands of magnetic-field pulses. Each had produced a field more than a million times stronger than the earth's and had concentrated a burst of energy comparable to an exploding stick of dynamite into a volume the size of a fist.
As was our custom, we submerged the electromagnet in liquid nitrogen, to reduce the electrical resistance in its coiled wires. The experimental sample, one of the early high-temperature superconductors, was positioned in the center of the magnet. We shut and locked the door to the steel bunker enclosing the magnet, its energy supply and all our data-collection equipment. An arming and charging sequence energized the power supply to 7,600 volts. One of us pressed the "FIRE" button, and the routine ended abruptly.