This paper reports a cold atmospheric pressure DC-driven air plasma brush.Three stainless steel needles are symmetrically mounted on a slot shaped PVC slab to act as the electrodes.The brush driven by a direct current(DC) power supply can generate an air plasma glow up to 30 mm wide with no inert gas addition and no air flow supplement.The plasma glow appears uniform no matter what kinds of material are processed.The measured current and the simulated current all show that each pulsed discharge including two peaks always occurs for different gaps between electrodes.Emission spectra measurement result shows that the obtained rotational temperatures are 300 K and the vibrational temperatures are 2250 K.Some reactive species are presented in the plasma glow,which suggest that the proposed plasma brush is beneficial to practical applications.
The influence of the gap on the absorption performance of the conventional split ring resonator （SRR） absorber is investigated at microwave frequencies. Our simulated results reveal that the geometry of the square SRR can be equivalent to a Jerusalem cross （JC） resonator and its corresponding metamaterial absorber （MA） is changed to a JC absorber. The JC MA exhibits an experimental absorption peak of 99.1% at 8.72 GHz, which shows an excellent agreement with our simulated results. By simply assembling several JCs with slightly different geometric parameters next to each other into a unit cell, a perfect multi-band absorption can be effectively obtained. The experimental results show that the MA has four distinct and strong absorption peaks at 8.32 GHz, 9.8 GHz, 11.52 GHz and 13.24 GHz. Finally, the multi-reflection interference theory is introduced to interpret the absorption mechanism.
