Micro-Solid-State Laser for Ignition of Automobile Engines

2 × 2 arrayed and passively Q-switched Nd:YVO4 laser under Dammann-arrayed pumping

“…It is worthwhile to point out that for breakdown in fuel mixtures, light intensities in the order of 100 GW∕cm 2 are necessary at the focal point of ignition [16]. In this work, an a-cut Nd:YVO4 crystal was used as the laser medium, and its high emission cross section is beneficial for low-threshold and multibeam laser oscillation However, the short lifetime of the upper level of this crystal, as well as its high emission cross section, is adverse to energy storage to produce high-energy pulses.…”

“…Furthermore, compared with single-point ignition, the multipoint ignition based on multiple pulsed beams that were injected into a cylinder significantly increases the laser energy absorbed by gaseous media and shortens the combustion time [11,15]. Nevertheless, if multiple pulsed beams originate from individual solidstate lasers, the multipoint ignition would encounter challenges in overcoming the large dimensions of the laser system and the cost [16,17].…”

Experimental investigation of the vibrational and thermal response of a laser spark plug

“…Chen, a plasma physicist, defines plasma as, "A quasineutral gas of charged and neutral particles, which exhibits collective behavior" [1]. This phenomena has been applied in several different LI experimental setups such as open air beam transfer [2, 3], transmission via fiber optic cables [4,5,6,7,8,9] or a single laser mounted directly onto the head of each cylinder [10,11]. Depending on the limitations set forth by the application, one of these LI strategies may provide certain advantages for initiating combustion over the others.…”

“…An alternative ignition source, such as LI, offers several advantages over a conventional spark plug. Unlike a spark plug where the point of ignition is limited to the top of the combustion chamber near the head, a laser with the proper accompanying optics has the capability to produce a plasma spark virtually anywhere in the combustion chamber, allowing for optimization of the combustion process [4,5,10,11,12]. This allows for more complete combustion to be achieved, as the spark location may be optimized to best conform to the geometry of the engine, resulting in an extension of lean limit operation [2,4,5,10,13].…”

“…The use of a plasma spark is rather attractive for pressurized applications as well, due to the fact that a combustible medium's optical breakdown threshold decreases with increasing pressure [16,17]. These ignition features allow for an engine to operate at a higher compression ratio and leaner A/F mixture providing greater fuel efficiency, reduced emissions and a more complete combustion process than is capable with the use of an electrode-based spark plug [2, 3,4,5,10,11,12,13].…”