Plasma kinetics study of a repetitive 10-NS pulsed plasma ignition for combustion

Abstract

Combustion efficiency and rate of ignition were shown to be improved when fuel-air ignition was initiated with highly non-equilibrium plasmas generated by highvoltage, nanosecond pulses, also known as transient plasma ignition (TPI). In order to optimize the pulse power parameters for plasma ignition for combustion, detailed experimental investigations of the effect of risetime and pulse repetition frequency (PRF) were conducted for atmospheric pressure static methane/air ignitions. Plasmas driven by 10 ns, 12 kV pulses at a range of PRF from 1 kHz to 10kHz were generated for combustion ignition with a conventional spark plug electrode configuration. Experiments revealed that a different mode in the plasma was initiated when the fuel/air mixture was ignited. At constant pulse duration and PRF, this plasma occurred earlier for the faster rise time (e.g. 4 ns) compared to the longer one (e.g. 8 ns) [1]. In addition, faster PRF favored the earlier plasma mode change or earlier ignition. Importantly, the kinetics of reactive plasma species that were generated during the TPI and combustion were investigated using optical emission spectroscopy (OES). Filtered high speed imaging in combination with electrical measurements are to help understand the plasma rotational temperature related to combustion that is initiated with different pulse rise times and PRFs at a constant pulse width of 10 ns. Gas temperature of the repetitively pulsed plasma ignition for combustion is discussed by measuring the rotational temperature of the second positive systems of nitrogen N2 (C-B).