Pulsed Discharges in Immiscible Layered Liquids: Fundamental Investigation and Application in Nanoparticle Synthesis

In-liquid pulsed nanosecond discharges produce highly dynamic plasmas that can be applied in different fields. In this study, we investigate the discharge dynamics of plasmas generated at or near the interface of water (with various electrical conductivities) and liquid heptane. The results indicate that at low conductivity (≤ 100 µS/cm), the discharges are most successful when the anode tip is in water and close to the interface. At these conditions, the plasma shape is filamentary, i.e. streamer-like. Meanwhile, at high conductivity (≥ 500 µS/cm), the highest percentage of successful discharges is observed for the case where the anode tip is in heptane, near the interface. The plasma generated at these conditions takes the shape of one wide and intense filament, i.e. spark-like. The transition from streamer-to-spark mode is also confirmed by electrical and optical measurements. Modifying water conductivity by adding metal salts and producing repetitive sparks in hepatne were found efficient to produce composite nanomaterial. This latter contains nanoparticles, that are produced via ions reduction by the plasma, and carbon matrix, that is produced via the disccociation of hepatne.