The Cutting Edge: Computing / Technology / Innovation : A Tiny Boiler to Keep PCs Cool
As computers become faster, heat buildup in the tiny spaces between circuit boards and semiconductors is becoming a big problem for computer designers. The conventional solution is to space circuit boards farther apart and use fans to dissipate heat. But computers perform much better when their components are close together, and simple air cooling does not keep up with the required heat removal. That’s why Digital Equipment Corp., which makes the superfast Alpha chip, turned to researchers at Pennsylvania State University’s College of Engineering.
Researchers there came up with a tiny alcohol-and-water boiler to cool high-heat areas inside the computer. First, an alloy is made by mixing very small particles of tungsten and copper with small amounts of activators. The mixed power is then injected into a mold to form a mini-boiler, then heated to form strong bonds between the particles. Liquid alcohol in the boiler is heated by the waste heat generated by the circuit board. The alcohol boils and is converted into alcohol vapor, which rises in the columns of the boiler. Converting from liquid to vapor cools the board, much like evaporation of sweat cools the skin in summer.
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Here’s to Blue and Green: Blue and green may be commonplace colors in nature, but they are a much-sought-after rarity in the world of lasers. Blue-green laser diodes are desirable because they have shorter wavelengths than the common red diodes, and such short wavelengths would make it possible to burn smaller pits into the surface of an optical storage device such as a compact disc. More pits equals more capacity, which equals longer recording time. That’s why corporate and university laboratories around the world are racing to develop a low-cost, low-power semiconductor laser that emits light in the blue-violet and green ranges.
Eagle-Picher Laboratory in Miami, Okla., working with the Department of Physics at North Carolina State University, recently announced development of an extremely bright diode in the pure-green region of the spectrum. With backing from the National Institute of Standards and Technology, Eagle-Picher combined its technology for producing high-quality, zinc-selenide crystals with fabrication techniques developed at NCSU.
Before the technology will be ready for commercial use, researchers must find ways to lengthen the useful life of the diodes. Researchers at Japan’s Hitachi Ltd. report getting blue laser results from conventional red lasers by forcing light from the red laser through an optical fiber with a diameter only a tenth of the wavelength of the light beam. The process is years away from commercialization, but if successful, it could be used to carve out pits on an optical disc even smaller than those produced by a blue laser.
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Molecular Fingerprints: Scientists at Los Alamos National Laboratory have come up with a way to identify companies responsible for oil spills or underground storage tank leaks by using non-radioactive tracers first developed for nuclear research. The tracers consist of organic molecules in which one or all of the hydrogen atoms have been replaced with deuterium (hydrogen with an extra neutron), and they provide unique, identifiable fingerprints. Because they are composed of the same chemicals as the host products, these molecular tags will not interfere with chemical processes.
This new technology could be used to run diagnostic tests on a leak at a natural gas facility without shutting down operations. Used in pipelines, it could show whether gas and oil is being stolen via illegal pipeline taps.
The tags could also determine whether underground storage tanks are leaking or identify the source of unreported oil spills at sea. Los Alamos is talking with oil and gas industry representatives about applications.
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Imaging Without X-Rays: Anyone who has ever held their hand over a flashlight knows that light can pass through a substantial amount of body tissue. But because the tissue scatters the light so strongly, detailed information about any interior structures, such as bones or possible tumors, is lost when the light emerges. A small fraction of the light, called ballistic light, does go directly through tissue without scattering and can reveal what lies under the skin. A USC physicist and his collaborator at the Eidgenoessische Technische Hochschule in Zurich, Switzerland, have figured out how to separate this gleam of ballistic light from the scattered light.
The method, which has been patented, takes advantage of the fact that ballistic light takes a straight path through tissue and thus emerges a few pico-seconds before the scattered light. A time-resolved hologram--which is a kind of holographic movie of all of the light passing through the tissue--is created, and by playing back only the early portion of the movie, doctors could see only the ballistic light.
It will be a long time before light replaces X-rays, however. To date, the technique has been able to render images only through tissue less than a centimeter thick.
