LASER IGNITION SYSTEM FOR INTERNAL COMBUSTION ENGINE

Laser ignition is considered to be one of the most promising future ignition concepts for internal combustion engines. It not only combines requirement of reduction of pollutant emissions but also improves engine efficiencies. In general, a well - defined ignition location and ignition time is of grea t importance for an IC engine. Spark plugs are well suited for such tasks but suffer from disadvantages, like erosion of electrodes & inflexible or un - optimal location of spark plug. Also the conventional ignition system cannot burn leaner air fuel mixture properly. In order to overcome the disadvantages of conventional ignition system, laser ignition system is researched upon. Laser ignition system gives the advantages like - it will reduce the NOx emission by 20%,it will be able to give improved efficiencie s .Also the Thermodynamic requirements of a high compression ratio and a high power density are fulfilled well by laser ignition system. . This paper outlines progress made in recent research on laser ignited IC engines, discusses the potential advantages and control opportunities and considers the challenges faced, construction and working of laser ignitor and the system requirements for laser ignitor. The igniting plasma is generated by a focussed pulsed laser beam. In order to generate the laser Nd:YAG is chosen as laser active medium emitting at λ em = 1064 nm, and Cr:YAG as passive saturable absorber. There are four different ways in which laser light can interact with a combustible mixture to initiate an ignition event namely - 1. Thermal initiation, 2. Non resonant breakdown, 3. Resonant breakdown, and 4. Photochemical ignition .Out of the above stated different ways non resonant breakdown is more frequently used because of its freedom in selecting the laser wavelength and ease of implementation. At present the laser ignition plug is very expensive and commercially not yet available .