Analysis of Dielectric Barrier Discharges under Unipolar and Bipolar Pulsed Excitation

In this work we experimentally examine the characteristics of a dielectric barrier discharge reactor driven by two distinct pulsed high voltage (HV) generators. Firstly, the operation under a HV generator delivering positive high voltage pulses with short (tenths of ns) rise and fall times in a low (up to 100 Hz) repetition frequency is illustrated. Then the DBD obtain with the use of a bipolar generator with a larger frequency range (several tenths of kHz) having rise and fall times in the microsecond scale is depicted. In the unipolar excitation regime two discharges per HV pulse occur: a first one during the rising part (or the plateau) of the applied high voltage and a second one during the falling part of the HV signal. On the contrary, the bipolar regime here studied presents a single discharge per HV pulse. Electrical as well as optical measurements give insight in the discharge characteristics in both excitation cases. Several electrical characteristics have been more particularly analyzed such as the quantity of transferred charge, the peak and the average plasma power and the power factor. These preliminary results show that the unipolar case could prove efficient to produce a reactive plasma but higher frequencies (i.e. several tenths of kHz) are needed than the ones used in the present work ones (only up to 100 Hz).