NTP Reactor Results Demonstrate Potential for Particulate Reduction: Non-thermal plasma (NTP) has been studied at various research sites for the application of an afterteatment device to reduce particulate. In such a system, the plasma produced between electrodes burns particulate collected in a filter. Since electric power drives the plasma reactor, it burns the particulate with less reliance on exhaust gas temperature. Therefore, the NTP concept is attractive especially for those vehicles frequently operated under low to medium load. Researchers from Daihatsu Industries and the Research Institute of Innovative Technology for the Earth have conducted a government-funded project to develop a NTP aftertreatment device for reducing particulate emissions in a diesel vehicle. This chapter reports the oxidation mechanism of particulate with non-thermal plasma, construction of the non-thermal plasma reactor, and some test results obtained under JC08 mode test conditions.