Study on Discharge Modes in Submillimeter Gaps of Needle-Plate Electrodes

With the development of micro-electromechanical systems, tiny electrical devices may be applied in different altitudes and atmospheric pressures. To investigate the characteristics of different discharge modes under low-pressure submillimeter gap conditions, a needle-plate electrode discharge system with variable pressure (101–10 kPa) and submillimeter gap distances (100–500 μm) was established. Initially, the initial breakdown voltages and discharge images under positive polarity for various gap distances and pressures were acquired using a high-voltage probe, oscilloscope, and image acquisition system. It was observed that three primary discharge modes exist in submillimeter gaps as pressure decreases: streamer discharge (101–70 kPa), arc discharge (60–40 kPa), and glow discharge (30–10 kPa). The volume of the positive column region in glow discharge was estimated through image processing, and the volumes for different pressures at each gap were statistically analyzed. A detailed analysis was conducted on the discharge morphology and the transition mechanisms between these modes.