Purpose/Aim

Low temperature plasma in atmospheric pressure air has a wide application prospect in dielectric modification, but how to produce uniform and stable plasma is an urgent problem to be solved. Porous dielectric discharge is expected to solve the above problems. However, the porous dielectric itself has the complexity and irregularity of structure, and the research on it is very little at present. Its discharge mechanism still needs to be systematically explored. In this paper, to further study the discharge mechanism of porous dielectric under the DC voltage, we built the research platform and analyzed the electrical characteristics of porous dielectric discharge and classical glow discharge at low atmospheric pressure.



Experimental/Modeling methods

The experimental device is mainly composed of high voltage DC power supply, discharge electrode, vacuum tank, oscilloscope and high voltage probe. The voltage and current waveform of plasma discharge are captured by the current trigger mode of oscilloscope.



Results/discussion

The Paschen curve of porous dielectric discharge is basically consistent with that of the classical glow discharge, but the voltage curve increases and the current curve decreases. The amplitude and rise time of the discharge current are different at the discharge time. The discharge current amplitude of porous media is smaller and the current rise time is longer under different air pressure. The reason why the voltage and current curves of porous media are different at the discharge time is that, the low conductivity of porous dielectric and its adsorption and dielectric barrier effect limit the plasma discharge process.



Conclusions

Due to the involvement of porous dielectric, the electrical characteristics and discharge mechanism of porous dielectric discharge are quite different from those of classical glow discharge at low air pressure. This also provides a reference for the study of porous dielectric discharge at atmospheric pressure and a new idea for plasma dielectric modification.