Impact of vibrationally resolved H₂ on particle balance in Eirene simulations

To evaluate the impact of transport of metastable, vibrationally excited states of the hydrogen molecule in dense and cold plasmas each vibrational state must be simulated as an individual species. Eirene neutral gas simulations of a one-dimensional flux-tube using a metastable-resolved model indicate a 30–50% decrease in the effective dissociation rate compared to simulations using a metastable-unresolved setup, which consider a single molecular species. Zero-dimensional Eirene simulations omitting transport effects predict a 25–65% decrease in the effective dissociation rate due to differences between the metastable-unresolved AMJUEL and the metastable-resolved H2VIBR rates available in Eirene. The exclusion of molecular hydrogen depletion via electronically excited states and vibrational transitions (Formula presented.) from the metastable-resolved rates reduce the effective dissociation rate. By accounting for the difference caused by the different collisional-radiative treatment of the metastable-resolved rates compared to the metastable-unresolved rates, transport effects are expected to be relevant under detached divertor conditions. It is, however, not possible to individually assess the role of the collisional-radiative processes and transport on the effective dissociation rate using the currently available atomic and molecular rates for the metastable-resolved and metastable-unresolved Eirene setups.