Who at school didn't like to play with a Van de Graaff generator? Wind it up, put a finger close to the metal shell and—zap!—a spark jolts across the gap. Now imagine the length of that electrical discharge isn't a few millimeters, but 60 meters. That's the accomplishment of a team of electrical engineers, which has developed a new way to create electrical discharges, or "arcs." As they will report in an upcoming issue of the Journal of Applied Physics, the researchers hooked up a thin, 60-meter-long copper wire to the terminals of a 270-kilovolt electrical supply. When they turned it on, the wire exploded into several short sections, forming beads of plasma, or conductive gas. These plasma beads grew rapidly until they formed a channel, allowing the discharge of a striking white arc. The researchers believe this "exploding wire" method, which needs less than 5% of the electric field required for an arc without an initial wire, could be used to make record-breaking arcs, hundreds of meters long. One application might be to capture lightning from thunderclouds, to save it from striking manmade objects on the ground.
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