One-dimensional hybrid simulation of the electrical asymmetry effect caused by the fourth-order harmonic in dual-frequency capacitively coupled plasma

A one-dimensional hybrid model was developed to study the electrical asymmetry effect（EAE） caused by the fourthorder harmonic in a dual-frequency capacitively coupled Ar plasma.The self-bias voltage caused by the fourth-order frequency changes periodically with the phase angle,and the cycle of self-bias with the phase angle is π/2,which is half of that in the second-order case.The influence of the phase angle between the fundamental and its fourth-order frequency on the ion density profiles and the ion energy distributions（IEDs） were studied.Both the ion density profile and the IEDs can be controlled by the phase angle,which provides a convenient way to adjust the sheath characters without changing the main discharge parameters.

Development of a dimensionless parameter for characterization of dielectric barrier discharge devices with respect to geometrical features

Non-thermal plasma（NTP） devices produce excited and radical species that have higher energy levels than their ground state and are utilized for various applications. There are various types of NTP devices, with dielectric barrier discharge（DBD） reactors being widely used. These DBD devices vary in geometrical configuration and operating parameters, making a comparison of their performance in terms of discharge power characteristics difficult. Therefore, this study proposes a dimensionless parameter that is related to the geometrical features, and is a function of the discharge power with respect to the frequency, voltage, and capacitance of a DBD. The dimensionless parameter, in the form of a ratio of the discharge energy per cycle to the gap capacitive energy, will be useful for engineers and designers to compare the energy characteristics of devices systematically, and could also be used for scaling up DBD devices.From the results in this experiment and from the literature, different DBD devices are categorized into three separate groups according to different levels of the energy ratio. The larger DBD devices have lower energy ratios due to their lower estimated surface discharge areas and capacitive reactance. Therefore, the devices can be categorized according to the energy ratio due to the effects of the geometrical features of the DBD devices, since it affects the surface discharge area and capacitance of the DBD. The DBD devices are also categorized into three separate groups using the Kriegseis factor, but the categorization is different from that of the energy ratio.