Applications of Power Modulator Technology to Ignition and Combustion

We report recent studies of applications of power modulator technology to ignition and combustion at USC, in collaboration with the Naval Postgraduate School, the Air Force Research Laboratory at Wright Patterson Air Force Base, and the Nissan Research Center. Transient plasma is under investigation as a technology for ignition of pulse detonation engines and other applications. It is attractive as an ignition source for most engines because of its ability to reduce ignition delay over broad ranges of temperature and pressure and combust leaner mixtures. Transient plasma is generated by applying high voltage nanosecond pulses that create volume-distributed arrays of streamers, which produce electronically excited species during nanosecond time scales. It has been demonstrated to be an energy efficient means of NO_x reduction for engine effluent, and has been applied effectively to ignition of pulsed detonation engines (PDE) and more recently extended to internal combustion engines. Several power modulator architectures for ignition applications are discussed, including a magnetic compression based solid state opening switch (SOS) pulse generator. The use of a solid state switch is compared with pseudospark or thyratron based architectures previously used. The pulse amplitude required depends on the exact geometry of the ignition chamber, combustor and corona electrode, but typical voltages used in our experiments are 50 to 70 kV with pulse energies on the order of 100 mJ to 1 J and pulse lengths from 17 to 150 ns.