Experiments on gliding discharge configuration for plasma assisted combustion

Summary form only given. Plasmas in thermal equilibrium have been in use in different kinds of combustion systems since the invention of the internal combustion engine and the spark ignition systems. Recently the possibility of using plasmas in non-thermal equilibrium for energy efficient production of radicals and excited species that increase the combustion speed has attracted attention. This interest stems not only from the need for more efficient combustion but also from a wish to increase fuel flexibility with a minimum of modification in existing combustor designs. There exist several methods to couple electrical energy to the flame zone or to the region upstream of the flame zone. The methods include, among others, techniques such as microwave excitation, inductive and capacitive discharges at different frequencies. It is however difficult to couple high electrical power to small volumes in such a way that the plasma created stay in non-thermal equilibrium. One relatively simple technique is to use a so called gliding discharge where the discharge starts out in thermal equilibrium but transitions to a state of non-thermal equilibrium as the discharge channel cools down and elongates due to an externally induced gas flow.