The fast-ignition technique is more like a petrol engine: first the fuel is compressed and only then is it ignited by a second laser pulse acting as a spark plug that is fired through a hole in the pellet.

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Instead of sparking the ignition when the piston is close to top dead center (when the air is compressed), that spark occurs as the piston is pulling away, when the air pressure is at its most turbulent, creating much faster ignition and more power.

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