Research on the Analytical Solution of Electron Number Density and the Plasma Impedance of Radio-frequency Glow Discharge at Atmospheric Pressure

To study the characteristics of radio frequency atmospheric pressure glow discharge (RF APGD), based on one-dimensional uniform model, the analytical solution of electron number density ne is deduced, from which ne can be calculated using the measured amplitudes of the discharge voltage and current. This analytical solution is appliable in conditions of α mode, high pressure and small electrode gap. An equivalent circuit model of resistance-capacitance serial-parallel-connection is proposed to describe the whole discharge region. The parameters of the equivalent circuit model can be obtained using the calculated ne. The correctness of this analytical solution is verified by comparing our ne with other's numerical simulation results. The experimental results show that the voltage and the electron number density increase almost linearly with the increasing of the discharge current density; the thickness of the sheath region, the equivalent capacitance of the quasi-neutral region and the equivalent capacitance of the sheath region negligibly change with the discharge current density; the equivalent resistance of the quasi-neutral region and the total impedance of the discharge region decrease with the increasing of the discharge current density. The results can also be used to point out some mistakes in others' previous work: falsely ignoring the thickness of sheath region and regarding the electrode gap as the length of quasi-neutral region; unreasonably overlooking the electric field of quasi-neutral region and regarding it as zero. In our future work, we hope to apply the analytical solution of ne to more circumstances, such as low pressure or large electrode gap. © 2020, High Voltage Engineering Editorial Department of CEPRI. All right reserved.