Electric strength of hydrogen in the nanosecond time range

Abstract

We have obtained information in breakdown voltage U _br of gas discharges as a function of gas pressure p and voltage surge of the discharge gap in the subnanosecond time interval. The experiments are made in a uniform electric field. The working gas is hydrogen. The pressure is varied from 0.1 to 6.0 MPa. The experiment is started at the minimal discharge gap width d = 0.15 mm. Then, d is increased with a step of 0.1–0.2 mm at a fixed gas pressure (0.1, 0.5, 1.0, 2.0, 3.0, 4.0, 5.0, and 6.0 MPa) until the discharge gap does not experience breakdown. It is found that an increase in pressure from 5.0 to 6.0 MPa increases the breakdown voltage in hydrogen by 40–170% depending on the discharge gap width. The results are plotted in the U _br vs. pd coordinates. It is shown that the charge similarity law is violated in the subnanosecond range. For the same product of pressure by the discharge gap, the breakdown voltage substantially depends on the gas pressure in the gap.