Discharge characteristics in soil under positive pulse voltage superimposed DC component

Considerable research efforts have been devoted to the study of the application of atmospheric discharge in soil remediation. Most of them focused on how to improve the degradation efficiency of specific pollutants. In contrast, the generation and development of discharge in soil is less studied, which restricts the widespread application of soil remediation. Pulse voltage is widely used to trigger discharge in soil, but the requirement for the power supply is relatively high. The current paper proposes a new form of discharge voltage, with positive pulse voltage superimposed on DC bias. The results show that the existence of DC component can effectively lower the required pulse voltage and enlarge the active corona volume, in which area most ionization and excitation happens. The characteristics of corona discharge in soil under DC voltage only, pulse voltage only and superimposed voltage with various voltage components are discussed in detail, according to the volt-ampere characteristics and discharge images from a series of experiments. The mechanism behind the experimental phenomenon are also discussed.