Energy-Controlled Atmospheric-Pressure Micro-Plasma Using Multistep External Ballast Capacitors

In this study, atmospheric-pressure (AP) micro-plasma discharge with a controlled energy has been developed. Using multistep external ballast capacitors, a dc voltage higher than the breakdown voltage of the plasma can be applied to an electrode. Because the stored energy at the external capacitor is injected directly into the plasma, the plasma is controlled by the stored energy of the external ballast capacitor. Discharge current, duration, energy, and light emission rate can be controlled by independently changing capacitance and applied voltage. Two types of discharges are analyzed: 1.22 nF–850 V and 10 nF–370 V. Using VI waveforms, an intensified charge coupled device (ICCD) camera, and emission spectroscopy, the electrical and spatio-temporal characteristics of the plasma are investigated. The two discharge types exhibit the same discharge energy, but there are differences in discharge duration, light intensity, and emission spectrum. Therefore, the discharge duration can be controlled at the same power, and consequently, the emission intensity can be controlled.