The purpose of this feature issue is to share information on laser ignition and related sciences and technologies. This feature offers five papers in the field that cover aspects of laser-induced laser ignition, including novel giant pulse micro-lasers, new phenomena of laser breakdown, advanced combustion systems and applications. These topics were chosen from the first Laser Ignition Conference (LIC) covering the topics of high brightness lasers for ignition and diagnostics, laser ignited engines for power generators and vehicles, and from a joint symposium with the Laser Display Conference covering applications of high brightness lasers.
© 2014 Optical Society of America
This feature issue of the Energy Express supplement to Optics Express is coordinated with the first Laser Ignition Conference (LIC) that took place 23–25 April 2013 in Yokohama, Kanagawa, Japan . The meeting brought together a diverse group of scientists from around the world who share an interest in the frontiers of research in laser ignition (see Fig. 1). It was included in the Optics & Photonics International Congress (OPIC), which had 676 participants from 23 different countries. The LIC meeting attracted 80 participants from 12 different countries. A total of 43 papers were presented during the conference, consisting of one plenary, one keynote, 11 invited and 30 contributed papers. There were 18 papers and six invited talks in the category of “High brightness lasers for ignition and diagnostics”. The world’s first laser ignited gasoline engine vehicle was demonstrated with micro solid-state photonics. In addition, new directions for temperature stable reliable and fiber delivered flexible laser ignition systems were discussed. The next category, “Laser ignited engines for power generator and vehicle,” had 15 talks, three of them invited, and a special session on “Plasma Assisted Combustion”. The advantages of laser ignition have been confirmed from various perspectives. The third category of “Applications of high brightness laser” had nine talks, including one plenary and three invited talks, and a joint symposium with the Laser Display Conference (LDC). The possible applications of this kind of high-brightness giant pulse laser include efficient nonlinear optics for laser displays, THz wave generation, and diagnostics, such as laser-induced breakdown spectroscopy and mass spectroscopy. Below, we summarize the five contributions in this special feature according to these general categories.
The first of these papers, by A. Nishiyama et al. , applies laser-induced breakdown ignition for microwave-enhanced plasma generation. Previously, microwave-enhanced plasma ignition was developed for standard spark discharge ignition engines to improve ignition stability. In this paper, the microwave-enhanced plasma generation technique was combined with laser-induced ignition to investigate the ignition process in detail. The second paper, by N. Kawahara et al. , provides time evolution of behaviors of laser-induced plasma and fuel spray, which were investigated by visualizing images with an ultra-high-speed color camera.
The third paper, by A. Yalin et al. , provides a concise review of research on high power fiber delivery for laser ignition applications. The research, using hollow core fibers, solid step-index fibers, and photonic crystal and bandgap fibers, is discussed in terms of exit energy, intensity, and beam quality. Recent demonstrations of spark delivery using large clad step-index fibers and Kagome photonic bandgap fibers are highlighted. The paper by G. Dearden et al.  outlines progress made in recent research on laser ignited internal combustion engines, discusses the potential advantages and control opportunities, and considers the challenges faced and prospects for its future implementation. With the recent development of higher average power and higher pulse frequency lasers, they expect that a multi-strike laser ignition system and associated combustion control can reduce the probability of misfires under high levels of dilution. The last paper, C. Manfletti et al. , studies the feasibility of implementing laser ignition in cryogenic reaction and control and orbital maneuvering thrusters. An experimental thruster with a single-coaxial injector element combustion chamber for testing with liquid oxygen/gaseous hydrogen and liquid oxygen/gaseous methane was designed for this purpose. This paper reports the locations of energy deposition, levels of delivered energy and associated ignition probabilities obtained. The results indicate the feasibility of using a laser system for the direct ignition of reaction and control and orbital maneuvering thrusters. They also highlight the further investigations and developments necessary for the implementation of miniaturized laser systems for vacuum ignition of cryogenic propellants.
The editors believe that the future of laser ignition is strong and lies in its diversity and depth to address basic energy problems within the context of applied practical challenges and limitations. We see great headway being made across the board in combustion engines from electric rockets to vehicles, including electric power generators. The editors note that the papers for this special issue come from authors from the United States, Europe and Asia. We thank the authors for their outstanding work and encourage researchers to continue to develop exciting theoretical and applied research in the field of laser ignition. We would like to express our gratitude to all authors and reviewers for their efforts in improving the manuscripts during the review process. We also thank Prof. Andrew M. Weiner, Purdue University, Editor-in-Chief of Optics Express, for his support and encouragement of this feature issue, and the OSA journal staff for their excellent support during the review and production processes.
References and links
1. LASER IGNITION CONFERENCE <http://lic.opicon.jp/>
2. A. Nishiyama, A. Moon, Y. Ikeda, J. Hayashi, and F. Akamatsu, “Ignition characteristics of methane/air premixed mixture by microwave-enhanced laser-induced breakdown plasma,” Opt. Express 21(S6), A1094–A1101 (2013). [CrossRef] [PubMed]
3. N. Kawahara, K. Tsuboi, and E. Tomita, “Laser-induced plasma generation and evolution in a transient spray,” Opt. Express 22(S1), A44–A52 (2014). [CrossRef]