The effect of negative feedback in multipoint nanosecond corona discharge

The results of studies on the use of low-temperature non-equilibrium plasma for the generation of ozone (O₃) in air and oxygen are presented. The results were obtained at facilities called plasma ozonators (PO), in which O₃ was generated by means of a nanosecond pulsed streamer corona discharge (NCD). The NCD was created in reactor chambers consisting of coaxially arranged high-voltage multi-pointed and grounded tubular electrodes. The high-voltage electrode was supplied with a pulse voltage generated by a three-stage Fitch frequency generator. The experiments used three types of PO with a capacity of 1–6 kW. The range of pulse amplitude was 50–75 kV, of pulse front duration was 150–250 ns, of pulse duration was 300–500 ns and of pulse repetition rate was 100–1000 Hz. The air flow through the PO varied from 10 to 1500 m³ h⁻¹. It has been established that the NCD is a system with negative feedback (NFE). The effect of NFE is that O₃ production with the help of NCD leads to a sharp decrease in corona streamer currents and energy introduced into the gas. Due to the effect of NFE with increasing O₃ concentration, the efficiency of its operating time in PO decreases by 3–4 times. A possible mechanism of the NFE effect, which is uniquely related to the structure of the nanosecond streamer corona, is discussed. (paper)