Non-thermal plasma reactor for lower power consumption

A system and method for treating a combustion exhaust stream includes admitting an exhaust stream into a non-thermal plasma reactor having at least one segmented non-thermal plasma element. The segmented element includes plurality of individually energizable electrode segments defining a plurality of corona volumes. in a preferred embodiment, the electrode segments are progressively smaller in size in the exhaust flow direction to provide optimum plasma volume variation. Individually energizable electrodes are selectively activated to effect variable corona volumes for treating an exhaust stream. Additional reactor segments are activated only as needed, such as during periods of high exhaust flow, for efficient treatment of the exhaust stream so as to maintain optimized high space velocity in the active corona volume. The segmented elements may comprise a variety of shapes, such as C-shaped elements, I-shaped elements, planar elements, swept-shaped elements, inter-digitized elements prepared from comb-shaped elements. The system and method are particularly suitable for gas pretreatment and downstream diesel particulate filter regeneration.