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Printer FriendlyReprinted with permission from Popular
Science, August 1999.
© Copyright, Times Mirror Magazines, Inc.
A Breath of Fresh Air
IMAGINE A FAN that has no moving parts, is completely silent, costs less than today's air movers, and runs more efficiently. That's what William O. Heath of the Pacific Northwest National Laboratory has developed.
Health's "ion wind generator" consists of two window-like frames with an air gap between them. The first frame has thin wires—guitar strings—strung across it in parallel rows. The second frame has a pair of steel rods positioned opposite each wire. Voltage is applied across the gap, ionizing the air around the wires. Propelled by the electric field, the ions zip across the gap and enter the rods to complete the circuit. As they do so, they collide with air molecules, speeding them up and creating a breeze.
So far, a prototype of the wind generator doesn't produce much of a pressure rise. "It doesn't have the 'oomph' that people would associate with a really good fan," admits Heath.
"Where I would see this being really valuable is as an air-sterilizing filter," he says. That's because the ions produced by the device kill bacteria and mold spores by disrupting their cell membranes. Placed inside a building's heating-system ducts, for example, a wind generator could clean circulating air without having to force it through a filter.—D.S.
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