Optimization of compact power modulators for transient plasma ignition

Non-equilibrated (non-thermal) plasma generated by short (ns), high-voltage (kV) pulses has attractive electron characteristics that fundamentally and favorably alter pre combustion chemistry and physics. This technology has been demonstrated in applications for airborne engines, including pulse detonation engines, in collaborative studies with Nissan in applications for internal combustion engines, as well as for more fundamental studies. We report recent studies where two compact power modulator systems are used to produce non equilibrium plasma in the transient, formative phase of an arc, and are applied to ignition and combustion (transient plasma ignition or TPI) in a constant volume reactor. In this work, ignition delays, a key parameter in the application to pulse detonation engines, were measured in transient plasma ignited C₂H₄-air in a constant volume reactor at atmospheric pressure. Two compact power modulators were used; a 12 ns SCR switched magnetic compression based pulse generator and an 85 ns pseudospark switched line-type pulse generator. The results show that despite the difference in energy delivered (70 mJ vs. 400 mJ), both systems achieve similar ignition delays across a broad range of equivalence ratios, and produce ignition delays up to two times shorter than with traditional spark ignition, confirming previous results obtained in an flowing system (pulse detonation engine). The results indicate that lower energy, more compact power modulators may be used for this application.