Predicting the low-pressure branch of the Paschen curve for hydrogen *

A physical and numerical model of Townsend discharge in molecular hydrogen has been developed for the gas switch project. The model allows to predict the low-pressure branch of the Paschen curve in 100 KV range.

In the regime of interest, electrons are in a runaway state and ionization by ions and fast neutrals sustains the discharge. It was essential to correctly account for both gas-phase and surface interactions (electron emission and electron back-scattering), especially in terms of their dependence on particle energy. The model yields result consistent with prior data obtained for lower voltage. The three-species model successfully reproduces the essential physics of the process. In future work, it can be expanded to include dissociation of H₂ molecules and resulting ionization cascades involving atomic ions and fast neutrals.