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We describe the details of a particular compact and robust Corona Discharge Device (CDD™) that generates non-thermal plasma in the harsh environment of a stoichiometric exhaust. This particular CDD™ can generate plasma power of up to 15W at exhaust gas temperatures to 850C. Optimizations of geometry, material selection, and thermal design were performed by a combination of simulation and experiment. This particular design considered tradeoffs of several factors, including plasma power, EMI shielding, thermal durability, high voltage interconnection, packaging size, and exhaust emissions reduction. This particular CDD™ was designed to meet most of the same durability and survivability specifications as an O2 sensor, since both are exposed to similar exhaust environments.

This paper reports efficient treatment of diesel emission with transient, non-equilibrium plasma created by a pulsed corona discharge. The transient plasma (∼50 ns) is found to reduce NOx emission in a flow of 1-10 liters/ second with energy cost ≤10-20 eV/molecule, corresponding to a fraction of source power of ∼5%. The efficiency of NOx reduction is a complex function of parameters that include pulse width, pulse polarity, current density, repetition rate, and reactor design. It was found that best efficiencies are correlated with a low current density (0.2A/cm2) and high repetition rate (1kHz) under high flow rate. Careful optimization of all these parameters is required to reach cost effective NOx reduction.