International Paper Presentation Organized by International Lasers Users Council (ILUC).

With the advent of lasers in the 1960s, researcher and engineers discovered a new and powerful tool to investigate natural phenomena and improve technologically critical processes. Nowadays, applications of different lasers span quite broadly from diagnostics tools in science and engineering to biological and medical uses. In this article basic principles and applications of lasers for ignition of fuels are concisely reviewed from the engineering perspective. 

The objective is to present the current state of the relevant knowledge on fuel ignition and discuss select applications, advantages and disadvantages, in the context of combustion engines. Fundamentally, there are four different ways in which laser light can interact with a combustible mixture to initiate an ignition event. They are referred to as thermal initiation, nonresonant breakdown, resonant breakdown, and photochemical ignition. 

By far the most commonly used technique is the nonresonant initiation of combustion primarily because of its freedom in selecting the laser wavelength and ease of implementation. Recent progress in the area of high power fiber optics allowed convenient shielding and transmission of the laser light to the combustion chamber.

However, issues related to immediate interfacing between the light and the chamber such as selection of ppropriate window material and its possible fouling during the operation, shaping of the laser focus volume, and selection of spatially optimum ignition point remain amongst the important engineering design challenges. 

One of the potential advantages of the lasers lies in its flexibility to change the ignition location. Also, multiple ignition points can be achieved rather comfortably as compared to conventional electric ignition systems using spark plugs. Although the cost and packaging complexities of the laser ignition systems have dramatically reduced to an affordable level for many applications, they are still prohibitive for important and high-volume applications such as automotive engines. However, their penetration in some niche markets, such as large stationary powerplants and military applications, are imminent...