Uncertainty Quantification of a Collisional-Radiative model for Hydrogen plasmas

A collisional-radiative model for the Balmer emission from low-temperature Hydrogen plasma is studied. The model is based on the most accurate cross sections available for the relevant processes. An uncertainty quantification study based on Polynomial Chaos expansion is performed for ionizing and recombining plasmas with conditions typical of the tandem discharge used in Neutral Beam sources for magnetically confined fusion reactors. Results show that uncertainties in the model results larger than a factor of 5 are obtained, much larger than the typical uncertainty in the measurements. The approach, however, allows to identify few processes that have the largest role in propagating the uncertainties and where increased accuracy has the largest impact.