Advanced Models for Negative Ion Production in Hydrogen Ion Sources

An advanced chemical model, based on the state-to-state approach, is applied to the modeling of a multicusp negative ion source. Simulations are performed with the GPKin kinetic code that solves the Boltzmann equation for free electrons self-consistently coupled with the Master Equations, following the evolution of the non-equilibrium electron energy distribution function (EEDF) and the vibrational kinetics of the ground and excited singlet electronic states of the H2 molecule. The virtual experiments reproduce the conditions of an experiment in the literature, showing the predictive character of the present approach and validating the model. The sensitivity of the results to the selected database of cross-sections for the electron impact-induced processes is investigated, clarifying the impact of more accurate datasets for specific processes in the mechanisms of negative ion production.