Development of a non-equilibrium 60 MHz plasma jet with a long discharge plume.

High-frequency plasma jets driven by voltages in the frequency range of 6-60MHz are developed. A long plasma jet, 40mm in length, is successfully produced by using a pair of ring electrodes outside a quartz tube. The electrode pair consists of a wide power electrode and a narrow ground electrode that is positioned at the head of the tube. The ratio of the length of the ground electrode to the length of the power electrode must be small in order to produce long plasma jets. The highfrequency plasma jet is operated in a non-thermal-equilibrium state at a gas temperature of around 60°C. Operation at the very-high-frequency of 60MHz leads to a lower discharge voltage and lower electron energy compared to lower frequencies of 6 and 13.56MHz. The ability of the very-highfrequency (60 MHz) plasma jet to produce reactive oxygen and nitrogen species in water is also investigated. High H2O2 and NO3- concentrations of more than 1mmol/l are realized by irradiating 3ml of deionized water with the plasma for a short period of 2min. [ABSTRACT FROM AUTHOR]