Laser igniters could spell the end for the humble spark plug


April 21, 2011

Spark plugs could soon be replaced be laser igniters

Spark plugs could soon be replaced be laser igniters

Internal combustion engines are likely to remain in widespread use for some time yet, but it's possible that we may be bidding adieu to that most iconic of engine parts, the spark plug. Researchers from Japan's National Institutes of Natural Sciences (NINS) are creating laser igniters that could one day replace spark plugs in automobile engines. Not only would these lasers allow for better performance and fuel economy, but cars using them would also create less harmful emissions.

Located at the top of each engine cylinder, spark plugs send a high-voltage electrical spark across a gap between their two metal electrodes. That spark ignites the compressed air-fuel mixture in the cylinder, causing a controlled mini-explosion that pushes the piston down.

One byproduct of the process are toxic nitrogen oxides (NOx), which pollute the air causing smog and acid rain. Engines would produce less NOx if they burnt more air and less fuel, but they would require the plugs to produce higher-energy sparks in order to do so. While this is technically possible, the voltages involved would burn out the electrodes quite quickly. Laser igniters on the other hand, could ignite leaner mixtures without self-destructing because they don't have electrodes.

The NINS scientists also address another limitation of spark plugs – the fact that they only ignite the area of the air-fuel mixture closest to them (the top), with much of the heat of the explosion being absorbed by the metal cylinder walls before it can reach down to the piston. Lasers, by contrast, could focus their beams into the middle of the column, from which point the explosion would expand more symmetrically – and reportedly up to three times faster than one triggered by a spark plug.

Additionally, engine timing could be improved, as lasers can pulse within nanoseconds, while spark plugs require milliseconds.

In order to cause the desired combustion, a laser would have to be able to focus light to approximately 100 gigawatts per square centimeter with short pulses of more than 10 millijoules each. Previously, that sort of performance could only be achieved by large, inefficient, relatively unstable lasers. The Japanese researchers, however, have created a small, robust and efficient laser that can do the job. They did so by heating ceramic powders, fusing them into optically-transparent solids, then embedding them with metal ions in order to tune their properties.

Made from two bonded yttrium-aluminum-gallium segments, the laser igniter is just 9 millimeters wide and 11 millimeters long. It has two beams, which can produce a faster, more uniform explosion than one by igniting the air-fuel column in two locations at once – the team is even looking at producing a laser with three beams. While it cannot cause combustion with just one pulse, it can do so using several 800-picosecond-long pulses.

So far, the laser-ignition system 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.

In the meantime, drivers wishing an upgrade from their "old school" spark plugs might be interested in Pulse Plugs, which reportedly boost engine efficiency and performance by storing ignition energy, then discharging it in the form of intense plasma balls.

The NINS research will be presented next month at the Conference on Lasers and Electro Optics, in Baltimore.

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away. All articles by Ben Coxworth

Now this is something I\'ve been wondering about since the 70\'s! WAY cool idea and I hope it comes out soon. By the way the Pulse Star plugs really do work I\'ve been using them for a couple years now. :-)


I think you\'ll find that the fuel in a cylinder burns, as the engine\'s not strong enough to contain explosions - that\'s \"pinking\".


Schmoe - First of all, it\'s \"pinging\" - not \"pinking\". Pinging or pre-detonation is caused when the A/F mixture ignites prematurely, usually due to excess heat, poor fuel, incorrect timing or a lean condition. The fact is in a normal internal combustion engine, the air and fuel do in fact ignite and explode under pressure.

Check the definitions of burning, combustion and explosion. Explosions are rapid thermal chemical reactions which result in heat and an expansion of gases. That\'s what happens in your car engine. Burning is what happens when you sit around the campfire...


\"Pinking\" is a word used to mean the same thing as \"Pinging\", perhaps more often in the UK.

But I love this idea - weapons-grade lasers, available at your corner auto-parts store!


Quite the teaser article! How about giving us some actual comparison numbers - e.g., percentage improved horsepower, percentage improved mileage. That kind of thing.

Loving It All

If Formula 1 isn\'t doing it, don\'t expect it anytime soon for the general public. You\'re not going to be able to just throw them in a car. The entire system will have to be designed around them.

The Pulse plug is a capacitive discharge plug and not remotely related to a \"laser plug\"

Al Lukasek

It matters not how they accomplish it. Anything replacing our present antique Spark Plug which comes in priced competitely & improves fuel efficiency is long overdue. Today\'s high tech Pulse devices, one which costs the same as 6 normal plug changes, aren\'t affordable for the average home mechanic who also is fond of Food. Yeh, it\'s Pinging, you just got to love pollution controls.



\'pinking\' is the correct term here in europe at least.

Dave Mcclure

Please excuse, but it Pings under our Bonnets. We often forget the the www in the address. My first correction this week, made it all the way to Monday. No offense intended, I love you guy\'s.



Dirty pinkos (old U.S. term,but not for pinging). once when I was very young I saw an injection/ignition system using lasers and exotic liquified gases(I forget the exact compound) but it burned exceptionally clean and it could reclaim the fuel several times.

There were a few articles on it in a performance boat magazine.

I always wondered why.

It was supposedly working but I always wondered if they got bought out,was it even real,etc.


Giving a hint as to how much voltage is needed, compared to standard plugs, would be interesting but not offered here. I suspect 20,000 volts or more would not be needed.

Robert Fox

Or....maybe we could switch to fuels that don\'t even need a spark plug in the first place? One less part to break on the engine.


Instead of improving just the spark plug, it seems to me that we should switch over to the MYT engine.

The idle power is 800 HP, it runs on any fuel and is about 1/10 the size of a regular ICE. Morgado says that a MYT car motor will be about 7 inches in length and 6 inches in diameter with mpg in the 150/gallon range. The Russians vistied Angel Labs in 2004 and now are claiming a similar motor design as their own and are planning to manufacture it.

Adrian Akau

But I love this idea - weapons-grade lasers, available at your corner auto-parts store! comment KellyRW - April 25, 2011 @ 06:56 am PDT

With a range of no more than a few inches a steak knife is a better weapon.

I wonder how increasing the oxygen supply in a superheated high presser nitrogen environment, will reduce the NOx production.

I have always thought that jumping the spark to an electrode on the piston would give Superior results.


Laser igniters? Oh please! Whats with the ICE improvements? Isn\'t it time to move to low pollution vehicles like electrics? Sad to see research being done on such inherently inefficient propulsion engines.

Sven Ollino

Swaan Son - April 26, 2011 @ 12:40 am PDT

When you can give me a maximum range of not less than 400 miles, with headlights, and a heater sufficient to keep the cabin at 72° in -15° conditions, and a battery that wont have to be replace over the life of the car, I will consider buying one, not before.


In regards to the MYT engine: It does NOT produce 800 horse power, that is ludacris... It does however produce 817 ft pounds of torque at 800 rpm resulting in approximately 124 horse power. The reason this is not in cars yet is because it is still in developement AND it simply doesnt produce enough RPM to be effective in a car yet...

Pulsar plugs are legitimate...

Gregory Minor


Thank you for your clarification; I stand corrected. I watched the video on the MYT motor and Morgado mistakenly said 800 HP when he should have said 800 foot pounds of torque. The MYT is still in development but there is an important announcement coming out on it soon.

Adrian Akau

Being curious, I went to Pulse plugs website, they don\'t have plugs for an F150, so I found some for a Toyota, then went to find an online review by other people that bought them, found some good reviews on Amazon, You all be the judge, I\'m glad they don\'t have plugs for my truck.


Man, what the heck was the writer smoking when that article was penned?? Since the spark typically occurs at about 15 degrees before Top Dead Center (your specs may vary), that piston is pretty darn close to the top of the block/surface of the head/spark plug when the spark happens. And really now, the flame propagates across the combustion chamber in just microseconds at best, so how much heat from each ignition cycle is going into the combustion chamber surface as opposed to the top of the piston and cylinder walls? When an engine is at a more or less steady state (warmed up), the head does absorb more heat than the block does due to the exhaust valves, but remember also, that there\'s a LOT of friction occurring between the piston rings and cylinder walls, thusly heating them up as well. So now just how much heat is flowing to where? As to the NOX problem, you\'re not going to get away from the 78 percent nitrogen in our atmosphere, so until you drop the compression ratios down to a VERY low spec, or put a catalytic converter on the ass end of the engine, they\'re always going to be there in large amounts.

Gearheaded Technoid

Expanded Viewpoint

Hmmm.... interesting that everyone has accepted the opening premise that all all internal combustion engines use spark plugs, whereas it is only the petrol ones that do....


I would think that it would be quite a challenge to keep the optics clean on a laser in a combustion chamber environment--and any laser powerful enough to ionize the fuel/air mixture would have to have really clean optics.


Slowburn - April 26, 2011 @ 10:03 am PDT

While I completely understand your concerns, my point was that too much effort is being put into fixing things that don\'t work well. It makes much more sense to try and R&D something new instead - like novel electricity storage or solar power capture tehnologies.

Sven Ollino

Yeah right.

If one looks at the latest experimental engine designs (engines we will have in the future) they rely on dieseling. Yes, for gasoline. This involves injecting the fuel at extremely high pressure to achieve extremely precise timings, doing away with the spark plug. There is no reasons to implement the laser ignition system since a conventional spark plug, only used to achieve engine warm-up would NEVER wear out.


There is one very good reason for continuing development on the internal combustion engine. They have not yet come up with a way to recharge a car quickly. If I am going on a vacation to visit family, I do not want it to be a 2-10 day trip each direction. I cannot afford the hotel bills and my patience is not enough.

We can abandon the internal combustion engine when they finally develop: 1) Ultra-capacitors that have high enough energy density to allow driving at least 200 miles between charges; or 2) batteries that can last at least 600 miles per charge; or 3) fuel cells that can provide the energy in large enough amounts to provide for regular long range driving.

And I am all for electric vehicles and am actually thinking about buying a Chevrolet Volt, but even the planned (2012?) Telsa Sedan with a 300 mile range is not good for long trips.

Give up the range and power and I think just about the entire world will GLADLY migrate to electric, but until it is there, if we can tweak what we have to get a bit more out, we are stupid not to.

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