Collisional phenomena and current buildup in the electrical breakdown of hydrogen

The electrical breakdown of hydrogen is examined by means of a two-dimensional mathematical model applied to the case of a 0.50-mm gap at atmospheric pressure. The calculations indicate a very rapid discharge development, characterized by a marked deviation of the axial density profiles from an exponential dependence, but with an approximately exponential variation of the discharge current. The axial-electron and ion-density profiles are similar in form and nearly balanced in magnitude. Notwithstanding the small magnitude of the space-charge field, the radial profiles of the electron and ion density displayed a definite tendency towards constriction, i.e., the incipient formation of a spark-type channel