Study on the Discharge Modes in a Microplasma Device with the Auxiliary Electrode

Summary form only given. Recently, microplasma has played an important role in various applications, such as medical devices, IJV radiation sources, environmental equipment and particularly information displays. However, the low efficiency of the microplasma due to the inefficiency of the glow discharge is currently a crucial problem. In order to improve the efficiency, a microplasma device structure with an auxiliary electrode was proposed and showed good results. However, the effects of the auxiliary electrode on the microplasma are not yet completely understood. This work investigates the microplasma generated in a microplasma device with an auxiliary electrode. In accordance with the discharge current peak time (discharge delay) and discharge current, the discharge modes were classified into three types. The first mode showed a decrease in both the discharge current and the discharge delay. The second mode showed a decrease in the discharge current and an increase in the discharge delay. Finally, the third mode showed an increase in the discharge current and a decrease in the discharge delay. According to both the measurement results and a mode analysis, the first and second modes showed an increase in the infrared (IR) efficiency with an increase in the auxiliary pulse voltage due to a decrease in the discharge current. In contrast, the third mode showed a decrease in the IR efficiency with an increase in the auxiliary pulse voltage due to an increase of the discharge current. From these results, the first and second modes are very attractive for microplasma in a plasma device with an auxiliary electrode to obtain high efficiency. Additionally, the effects of the position of an auxiliary electrode on the discharge mode were investigated by varying both the distance of the coplanar-gap and the pressure.