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Due to the demands of the market to increase efficiency and power density of large MW size gas engines, existing ignition schemes are gradually reaching their limits. These limitations initially triggered the development of laser ignition as an effective alternative, first only for gas engines and now for a much wider range of internal combustion engines revealing a number of immediate advantages like no electrode erosion or flame kernel quenching. Within this broad range investigation, laser plasmas were generated by ns Nd-YAG laser pulses and characterized by emission and Schlieren diagnostic methods. High-pressure chamber experiments with lean hydrogen- air mixtures were successfully performed and allowed the determination of essential parameters like minimum pulse energies at different ignition pressures and temperatures as well as at variable fuel air compositions. In this way, relevant parameters were acquired allowing estimation/ development of future laser ignition systems.

The development of vehicles continues to be determined by increasingly stringent emissions standards including CO2 emissions and fuel consumption. To fulfill the simultaneous emission requirements for near zero pollutant and low CO2 levels, which are the challenges of future powertrains, many research studies are currently being carried out world over on new engine combustion process, such as Controlled Auto Ignition (CAI) for gasoline engines and Homogeneous Charge Compression Ignition (HCCI) for diesel engines. In HCCI combustion engine, ignition timing and combustion rates are dominated by physical and chemical properties of fuel/air/residual gas mixtures, boundary conditions including ambient temperature, pressure, and humidity and engine operating conditions such as load, speed etc.

Due to the increasingly stricter emission legislations and growing demand for lower fuel consumption, there have been significant efforts to improve combustion efficiency, while satisfying the emission requirements. Homogenous Charge Compression Ignition (HCCI) combustion offers significant efficiency improvements compared to conventional gasoline engines. However, due to the nature of HCCI, fully homogeneous charge HCCI combustion can be realized only in a limited operating range. Control of HCCI engines to obtain the desirable operation requires understanding of how different charge variables influence the cyclic variations in HCCI combustion. Under certain operating conditions, HCCI engines exhibit large cyclic variations in ignition timing. Cyclic variability ranging from stochastic to deterministic patterns can be observed. One important design goal for engine development is to minimize cyclic variability.