Study on the Formation Mechanism of Soil Discharge Dark Space Under Negative DC Voltage

In recent years, there has been a notable increase in research activity concerning the remediation of soil using nonthermal plasmas (NTPs), as well as the study of discharges in soil. In examining the phenomenon of soil discharges under negative direct current (dc), researchers have identified the presence of discharge dark spaces. It is well established that the Faraday dark space is present under negative glow discharge. However, no instance of the discharge of dark space has been documented in soil discharges. It is noteworthy that, akin to the dark spaces observed in gas discharges, which occur exclusively in negative glow discharges, soil dark spaces are only discernible under negative dc discharges. Nevertheless, the underlying mechanism responsible for their formation remains elusive. In order to gain a deeper understanding of the mechanism of soil discharges and the formation of dark space regions, a new model of soil discharges is proposed in this study. Based on this model, we derived an expression for the extent of the dark space region. Furthermore, we explored the effect of the dark space region on soil discharge. These studies facilitate the development of technologies for the remediation of pollutants by soil discharge and provide new insights for further research on the potential mechanisms of soil discharge.