Atmospheric glow discharges from the high-frequency to very high-frequency bands

This letter reports an experimental investigation of an atmospheric glow discharge in both the high-frequency (HF) band of 3-30 MHz and the very high frequency band of 30-300 MHz. At constant input power, increased frequency is found to change little the electron density and to reduce slightly the electron excitation temperature. Significantly, an eightfold frequency increase from 20 to 80 MHz leads to a 20-fold increase in the maximum plasma power without plasma constriction. The maximum power density of 355 W/cm3 achieved at 80 MHz is far greater than those reported in the HF band