Researchers Say Lasers May Replace Spark Plugs


OKAZAKI, Japan ~ ( ~ The steadfast spark plug has remained relatively unchanged in design since its invention 150 years ago, but now researchers are claiming lasers can do the job more efficiently.

Researchers at Japan’s National Institutes of Natural Sciences have developed a system using small lasers to focus light beams into cylinders of an internal combustion engine to light the fuel-air mixture. Not only would this allow cars to provide better performance and fuel economy, but it could also reduce emissions as well. One downside is the high-pulse energy required to cause ignition; it takes a lot of energy to ignite the fuel-air mix. “In the past, lasers that could meet those requirements were limited to basic research because they were big, inefficient, and unstable,” Takunori Taira of the National Institutes of Natural Sciences said, “nor could they be located away from the engine, because their powerful beams would destroy any optical fibres that delivered light to the cylinders.”

To overcome this limitation, NINS researchers created a small, robust laser by heating ceramic powders, fusing them into optically-transparent solids, and then pressing them into spark plug-sized cylinders. The laser plugs gather energy from compact, lower-power laser light sent through fiber optic cable in pulses 800 trillionths of a second long. Several of these pulses, in two beams and focused at different depths, create a more uniform explosion by igniting the fuel-air mix at different locations at once. This would allow motors to run a leaner fuel-air mix, burning more oxygen and reducing production of nitrogen oxide (NOx) gas pollution. The research team is also looking into producing a laser with three beams.

So far, the laser-ignition system is still in production and hasn’t been installed in an actual automobile. The scientists are reportedly in negotiations with a large spark plug manufacturer and with global auto components manufacturer DENSO Corporation. The NINS team’s research will be presented next month at the Conference on Lasers and Electro Optics, in Baltimore.

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