Establishing an equivalent circuit for a quasihomogeneous discharge atmospheric-pressure plasma jet with a breakdown-voltage-controlled breaker and power supply circuit

To more accurately simulate the I-V diagram of a homogeneous and a filamentary plasma discharge with an equivalent circuit model, this study employed a breaker and passive circuit components and calculated the discharge parameters, such as equivalent discharge resistances and potential distribution, in an atmospheric pressure plasma jet (APPJ). In addition, we calculated the gas-gap and dielectric capacitances of the APPJ and added a power supply equivalent circuit. Compared with other circuit models that use switches or a time-controlled current source to simulate the discharges, our present circuit model uses a breakdown-voltage-controlled breaker for the homogeneous discharge and resistors with high-frequency switches for the filamentary discharge. We employed potential simulation to obtain the equivalent dielectric capacitance in the APPJ and then derived the gas-gap capacitance. We also replaced the ideal sine wave power supply with the equivalent circuit of the common double-peak waveform power supply. MATLAB Simulink was used to construct an equivalent circuit model and the discharge area ratio, breakdown voltage and filamentary equivalent resistance were obtained via I-V waveform fitting. We measured the plasma I-V waveform with a 20 kHz frequency, various voltages (6, 12 and 15 kV), a gas flow rate of 30 standard liter per minute (SLM) and two types of gas (Ar and He). The simulated and experimental I-V waveforms were very close under the different conditions. In summary, the proposed equivalent circuit model more meaningfully describes the plasma physics to simulate homogeneous and filamentary discharges, achieving results that are compatible with our experimental observations. The findings can help with investigating plasma discharge mechanisms and full-model simulations of plasma.