Some properties of radio frequency gas discharges in air at atmospheric pressure

Measurements were made on steady-state gas discharges maintained by RF power in air at atmospheric pressure. The frequency range 1-30 MHz was covered. It was found that these discharges operate as either RF glow or RF arc discharges. The characteristics of each are very similar to those of the corresponding dc discharge types. These RF discharges are quenched after each half-cycle and must be reignited in the following half-cycle. The minimum voltage for reignition is about 350 V. After reignition the discharge voltage is high (≥275 V) for glows and low (≥30 V) for arcs. The discharge type can alternate with polarity. The resulting asymmetric voltage-current characteristic can cause rectification. By their non-linear behavior discharges can produce high-order harmonics of the frequency at which they are maintained. These discharge properties account for various interference problems caused by parasitic RF discharges in the vicinity of high-power RF transmitters.