Generation of Dielectric Barrier Discharge Plasma in Supercritical Argon for Material Synthesis

Plasma discharge was generated by high-frequency (HF) power in supercritical argon (critical pressure: 4.86 MPa, critical temperature: 150.7 K). Dielectric barrier discharge (DBD) enabled us to continue to generate a stable plasma even in high-pressure argon in more than 1 h by using parallel plate electrodes. Furthermore, a discharge plasma at a high pressure was generated in a wide area (150 mm2) between these electrodes for material synthesis. From optical emission spectra of argon at atmospheric pressure to critical pressure, it was observed that the plasma at a high pressure generated the same active species as the plasma at a low pressure. A weak broadening of plasma emission spectra was observed when pressure increased. Moreover, a carbon thin film was synthesized from n-pentane by using the novel reaction field of DBD. The carbon thin film was analyzed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Raman spectroscopy.