Laser Spark Plug Development and Engine Testing - Design of a diode side pumped solid state passively Q-switched laser for use as an ignition source f

To meet the ignition system needs of future lean-§burn natural gas engines a diode side pumped, §passively Q-switched, Nd:YAG laser was developed and §tested. Laboratory experimentation used a wide range §of input parameters that when combined produced §brilliant sparks in air. The results show a strong §dependence of the output on the output coupler §reflectivity, Q-switch initial transmission, and §gain media dopant concentration. The results show §peak power levels of up to 3MW and peak focal §intensities of up to 560 GW/cm2. Engine testing was §performed on a Ricardo Proteus single cylinder §research engine. The engine testing consisted of a §comparison of the in-cylinder, and §emissions behavior. All engine parameters were kept §as constant and the equivalence ratio was varied §between 0.8, 0.9, and 1.0. The test laser was §constructed with a 30% output coupler, 32% Q-switch §initial transmission, and a 0.5% Nd concentration §rod all pumped by approximately 1000 Watts of §optical power. The test laser single mode §output pulse had an energy of 23 mJ, with a §pulsewidth of 10 ns, and an M2 value of 6.55. This §output produced focal intensity of 270 GW/cm2.