Abstract
In spark-ignition engines, ignition starts by the support of plasma energy supplied by spark discharge. This system has lasted for one hundred years. Recently, several new concepts have been proposed instead of ordinary spark discharge in order to match deeper EGR (Exhaust Gas Recirculation) and/or leaner mixture with high boosted condition for the near future engines. This paper reviews some newly developed ignition systems and discusses the advantages and disadvantages. For example, plasma jet system, repetitive pulse plasma discharge with high-response system, laser ignition system, microwave system, etc. are introduced. Eventually, all the systems have to consider how to utilize plasma phenomena. Owing to better plasma, the engine combustion would be stabilized and improved.
