Laser‐initiated ignition

Abstract

After an introduction illustrating the relevance and motivation of laser ignition of engines, the physical background is reviewed in a first technical section. This mainly comprises the mechanisms of plasma formation, which are the generation of first free electrons and their avalanche-like multiplication, being illustrated by emission and Schlieren diagnostics. Thereafter, combustion fundamentals are discussed leading to an understanding of flammability and minimum ignition laser energies. An important section is represented by the description of the components of laser ignition. This covers the setup and function of a diode-pumped passively Q-switched solid-state laser system, which preferentially is based on Nd:YAG. Other laser sources are mentioned for comparison. Furthermore, multiplexing schemes are discussed that are motivated by cost-saving issues. It is explained why present-day optical fibers are not capable of transporting nanosecond ignition pulses. As a last section, the concepts for an incoupling window and focusing optics are elucidated. Finally, after a summary, in an outlook the chances for commercial realization are analyzed.Sectional view of a prototype of a laser spark plug with an expanding flame kernel.

Effects of Energy Deposition Characteristics on Localised Forced Ignition of Homogeneous Mixtures

“…The findings based on Figure 6 indicate that it is possible to obtain successful ignition and self-sustained combustion even for the fuel-lean cases by judicious choice of R, b sp , a sp and these parameters can be altered independently of each other in case of laser ignition. The present findings are consistent with recent experimental findings [8,[27][28][29][30][39][40][41] that laser ignition can be effective in igniting fuel-lean mixtures by altering the laser power (i.e. equivalent to the variation of a sp ), laser beam radius (i.e.…”

Photo-responsive behaviors and structural evolution of carbon-nanotube-supported energetic materials under a photoflash

“…The ignition and combustion of energetic materials have aroused great interests in the past decades, which are of great value in many practical fields such as remote control, intelligent explosion, gas generators and aerospace science and technology [1][2][3][4][5]. It is generally believed that the ignition of energetic materials can just be initiated by the light source with a specific wavelength and high power density like high-power lasers due to the requirement of high energy output within a very short time.…”

Study of an actively Q-switch erbium-doped fiber laser in symmetric configuration

“…A relative simplicity of Q-switched fiber laser (QS-FL) makes them attractive for applications in many fields including super-continuum generation [1][2][3], distributed fiber-optical sensing [4], laser-initiated ignition [5], etc.…”