Stringent exhaust emissions norms and demand of high thermal efficiency can be achieved by ignition of lean air-fuel mixtures in IC engines. However, lean combustion is associated with slower flame propagation speeds, reduced power output and struggle with emissions standards due to complex lean NOx after-treatment. Engine power output can be improved by increasing initial in-cylinder pressure by turbocharging. Increased in-cylinder pressure however
requires high secondary voltage to breakdown the gases and initiates the combustion in a spark ignition (SI) engine using conventional spark Ignition system. The amount of energy released between the spark electrodes depends mainly on the pressure inside the combustion chamber at the time of ignition (towards the end of compression stroke) and the distance between these electrodes. An increase in the incylinder pressure keeping the same electrode distance would require increased secondary coil voltage applied to the spark plug, which would lead to erosion of electrodes over time. Flame propagation speed in lean mixtures can be increased either by optimizing the position of the ignition point inside the combustion chamber or by multipoint ignition [1, 2, 3]. However point of ignition remains always close to the top of the combustion chamber in a SI engine and cannot be varied too much from this location. These limitations of conventional ignition systems can be overcome by a durable high-energy, electrode-less ignition system, which also has flexibility in terms of spark location, such as laser ignition (LI) system.