Breakdown voltage curves in direct current discharges in molecular gases at microgaps

This Letter reports on experimental studies of the direct current breakdown voltage curves in oxygen, dry air, nitrogen and hydrogen discharges with parallel-plane electrodes separated from 1 to 100 μm. For the gaps sizes greater than 5 μm, the obtained breakdown voltage curves exhibit U-shaped form and follows the Paschen law. For the gaps less than 5 μm, however, in the left-hand side the curves show departure from the standard scaling law. To the author s knowledge, there is no data for the breakdown voltage in microgaps for some of the considered molecular gases. Owing to the lack of experimental data in microgaps, measured data represent basic design data of high voltage equipment.