Generation and Reactivity of Field Emission-Driven Discharges in Cryogenic Liquid and Supercritical Fluids

While plasmas in high-density media, such as liquids and supercritical fluids (SCFs), have attracted much attention, the discharge spaces often become gas(-like) states with their generations. In contrast, by using carbon nanotubes as electrodes, we have succeeded in generating a discharge while the discharge space remains in the SCF or liquid state. Previously, such discharges had been confirmed in micro-gap or surface-discharge dielectric barrier discharges, but in this study, similar discharges have been achieved using a CNT wire in a DC discharge with a wire-to-plate electrode in cold liquid and supercritical fluids, argon and nitrogen. The discharge can be sustained with a very long gap of about 1 mm for highly packed fluids with a relatively small voltage of 1-3 kV. The voltage-current characteristics well represents a Fowler-Nordheim plot, suggesting that the discharge is dominantly driven by field-electron emissions. Since the discharge emits light from the entire space between the electrodes, it is considered to be different from corona discharge. It has been also confirmed that reactions, such as oxidation, can occur on a metal substrate as a counter electrode of the CNT wires . Further details will be presented at the conference.