The breakdown voltage characteristics and the secondary electron production in direct current hydrogen discharges for the gaps ranging from 1 μm to 100 μm

This Letter reports on experimental studies of the direct current breakdown voltage curves in hydrogen discharges with parallel-plane electrodes separated from 1 μm to 100 μm. Based on the breakdown voltage curves, the role of the enhancement of the secondary electron emission due to high electric field in microgaps has been estimated. The secondary electron emission due to high electric field generated in microgaps depends primarily on the electric field E   rather than reduced electric field E/NE/N, leading directly to the violation of the Paschenʼs law.

► New experimental set-up has been developed.
► For the first time, breakdown voltage curves for dc hydrogen microdischarges have been measured for microgaps.
► For the firs time, the effective yield in microgaps has been estimated.
► The role of the field emission has been clearly resolved.
► Proposed model of the secondary electron emission provide values that are in a good agreement with the experimental data.