Gas Breakdown in Microgaps With a Surface Protrusion On the Electrode

This paper summarizes our recent studies on a gas breakdown in microgaps with a surface protrusion on the electrode with more detailed information. The breakdown voltages are quantified when the discharge enters into the subnormal glow region with negative differential resistance, using a 2-D fluid model. The breakdown characteristics are evaluated with the effects of the protrusion geometries, such as protrusion size and aspect ratio, as well as the discharge polarity. It is found that in an atmospheric-pressure microgap, the protrusion size has a more profound effect on the breakdown voltage than its aspect ratio, which is due to the competition between the current density enhancement and the effective cathode emission area. As gas pressure varies, the surface protrusion on the electrode results in a combined Paschen's curve, which transits from long-gap behavior at low pressure to short-gap behavior at high pressure. The key parameters on the breakdown characteristics with the surface protrusion are elucidated.