18-22 April 2011, Singapore, Republic of Singapore


E. Wintner

Photonics Institute, Vienna University of Technology, Gusshausstrasse 27, A-1040 Wien, Austria

Abstract.  Plasma is the predominant status of matter, in stars as well as in interstellar space. In science, it was only recognized rather late as a specific (fourth) state of matter: Sir William Crookes described it in 1879 as “radiant matter”, Irving Langmuir created the name “plasma” in 1928.

Technically generated plasma is employed very broadly in modern technology. Some examples are Plasma Displays, Fluorescent Lamps (also the modern Energy Saving Lamps), Corona Discharges (for e.g. Ozone generation, or even engine ignition), arc welding and cutting, reactive ion etching, mass spectroscopy, ion rocket engines and many more.

Very early since the development of the laser, it was also employed to generate a plasma (spark) in air or on surfaces. Generally, for this purpose at least ns (“Giant”) pulses have to be used. In more recent times, pico- and femtosecond pulses have allowed to create plasma very easily and effectively. Laser fusion may represent the ultimate application in this direction, based on highly amplified ns pulses for inertial confinement or ps pulses designed as fast igniter.

The idea of employing laser pulses for the ignition of engines was attempted for the first time in 1978 [1], although with inadequate tools like the CO2 laser. After a long time of inactivity in this field, about 10 years ago a few institutions like Vienna University of Technology first resumed this ap-proach with the help of modern type solid-state lasers and started systematic investigations around the idea of laser ignition of internal combustion engines. Now, this technique has reached a high degree of maturity; remaining problems lie on the development level and are to be solved soon. Ambitious product development by leading engine producers or ignition equipment suppliers has been started world-wide since several years and, as a result, in one or two years laser ignition will probably be imple-mented into high power gas engines or, somewhat later, high-priced automotive engines. This talk will provide an overview on advantages and critical issues of laser ignition, on laser requirements and la-ser-matter interactions involved, furthermore different system concepts and alternative approaches which are considered to be less advantageous or even unrealistic.

As a perspective for the future, laser ignition is considered to be an indispensable process for the ignition of chemical reactions in general [2], and it will, with high likeliness, be implemented e.g. into rocket engine ignition (attitude control in the first place) and jet engine (re)ignition.

References :
[1] A.J.D. Dale, P.R. Smy, R.M. Clements, Laser ignited internal combustion engine – an experimental study; SAE Congress, paper 780329, Detroit (1978)
[2] M. Lackner (ed.), Lasers in Chemistry. Probing and Influencing Matter; 2 vol (Wiley Inc.), ISBN 978-3-527-31997-8 (2009).