Influence of nitrogen impurities on the characteristics of helium discharge at high pressure

In this paper, a helium model with nitrogen impurities was established by COMSOL Multiphysics. In order to validate the model, the results of this model were compared with those of the pure helium model and the experimental data. A concept named "reaction chain " was applied to investigate the effects of the nitrogen impurities and elucidate the underlying mechanisms. In terms of discharge mechanisms, the Penning ionization of the He* and N-2 can consume He* constantly and directly, which can shorten the reaction chain for the production of dominant ions. The direct ionization of ground state nitrogen molecules can produce more electrons to strengthen the effects of electron avalanche, which will further intensify the reactions. Therefore, the presence of nitrogen impurities can simplify the reaction pathways and intensify the reactions. As a result, the presence of nitrogen impurities can decrease the breakdown voltage remarkably. (C) 2022 Published by Elsevier Ltd.