Laser igniter shows promise as the next generation spark plug

We know the internal combustion engine isn't going anywhere (so to speak) for a few decades yet. Japanese researchers may have now come up with an important contribution to its longevity.

Gizmag reports that this coming month, a team from Japan's National Institutes of Natural Sciences (NINS) will use the upcoming Conference on Lasers and Electro Optics in the US city of Baltimore to unveil a laser ignition device conceived to replace one of the petrol engine's greater points of inefficiency: the spark plug (pictured).

Ask any physicist to compare internal combustion engines and they'll tell you the diesel is the more elegant way of achieving the desired outcome -- read: a bang inside a combustion chamber, displacing a piston that turns a crankshaft connected via a gearbox to a driveshaft that goes to a second gearbox -- the differential -- which redirects the kinetic energy along an axle to a wheel.

That's because oilers achieve combustion by compression. That means ignition is intrinsic to its workings -- it doesn't need the bolt-on system of coil and leads and plugs used in petrol engines. The spark plug is an inherently inefficient means of ignition. It sits at one end of the combustion chamber, meaning the fuel-air cloud burns unevenly, producing toxic nitrogen oxides that morph into smog in the atmosphere. The uneven burn also leaves much of the thermal energy that should be displacing the piston -- instead dissipating through the metal walls of the cylinder.

One conventional counter to such inefficiencies is to enrich the mixture -- add more petrol -- which, of course, takes its toll at the pump. It's possible to produce higher-energy plugs with a stronger spark, but only at a cost in electrode damage and therefore the lifespan of the plug.

The NINS team has come up with a promising laser device addressing most of the old plug's shortcomings. Its variable focus allows the sparking point to shift the centre of the combustion chamber -- or whatever is calculated to be the optimum point -- creating a more symmetrical flame and boosting burn efficiency. For auto makers and tuning houses, ever in search of new ways to extract more power from less fuel, this promises to open up a raft of new opportunities.

The NINS breakthrough comes not in the idea but in the execution. The idea of laser ignition isn't new, but to date laser technologies have presented their own challenges, particularly in extracting a lot of power from a small package. A petrol engine needs a laser capable of generating about 100 gigawatts per square centimetre in pulses of more than 10 millijoules. Until now, those kind of numbers have been restricted to lasers too large, and unstable for the purpose.

Just 11mm long and 9mm wide, the NINS team's high-powered device uses a ceramic lens infused with metal ions to make it precision tuneable. One major benefit is the capacity to generate multiple ignition points in the chamber using multiple beams with timing variable in nanoseconds and picoseconds -- that's trillionths of a second -- rather than the milliseconds in which conventional plugs work. The prototype to be demonstrated this coming month uses twin beams, and they're already working on one with a third.

The device has yet to find its way into a vehicle for real-world testing. But Gizmag reports the NINS team is in negotiations with 'a large spark plug manufacturer' and with multinational components manufacturer Denso Corporation.

Read the latest Carsales Network news and reviews on your mobile, iPhone or PDA at carsales' mobile site...