Realization of DC atmospheric pressure glow discharge without external airflow

A new needle-to-cylinder electrode structure with small gap (1.5 mm) was designed to realize the stable gas discharge in ambient air. The stable corona discharge and the stable glow discharge were realized without external airflow, which was proved by the discharge waveform stored in the oscilloscope, the discharge pictures recorded by the digital camera and the voltage-current plot. The image of the glow discharge showed that there was a negative glow region, Faraday dark space, a positive column region and an anode spot. Also the experiment and the COMSOL simulation showed that the needle with a diameter of 56.4 mu m can realize the glow discharge while the needle with a diameter of 626 mu m can not. The reasons for the realization of the glow discharge by the small gap between the needle and the cylinder were analyzed. It also shows that the glow discharge is easily realized with the black spot on the cylinder surface and a proper ballast resistor value (larger than 2 M Omega and less than 30 M Omega). The needleto-cylinder electrode structure is easy to fabricate by MEMS technology, which can be used in portable analytical instruments. (C) 2014 Elsevier Ltd. All rights reserved.