Study of the Effect of the Field Emission on the Breakdown Voltage Characteristic of Direct Current Nitrogen Microdischarges
M. Radmilović-Radjenović, B. Radjenović
Institute of Physics, University of Belgrade, Pregrevica 118, Belgrade, Serbia
Received: April 27, 2018; revised version March 26, 2019; in final form March 28, 2019
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This paper reports on theoretical studies of the role of the field emission effects in direct current nitrogen discharges between the electrodes separated from 0.5 μm up to 100 μm. The effect of the various parameters on the breakdown voltage curves and current densities was calculated by using a Breakdown Voltage and Current Density in Microgaps Calculator. The obtained results clearly show that the shape of the potential barrier depends on the gap size and the work function. The high electric fields generated in microgaps combined with the lowering of the potential barrier seen by the electrons in the cathode as an ion approaches lead to the onset of ion-enhanced field emissions and the lowering of the breakdown voltage. Therefore, electrical breakdown across μm gaps is initiated by the secondary emission processes instead of a gas avalanche process and occurs at voltages far below the minimum predicted by the standard scaling law. It was found that the gap size, the gas pressure, enhancement factor, and the effective yield affect both the breakdown voltage curves and the current density. Presented results provide better understanding of the electrical breakdown in microgaps.

topics: field emission, enhancement factor, microdischarges, breakdown voltage