Uncertainty quantification and sensitivity analysis of the energy and particle sources from hydrogen neutral beam injection in a JET-like fusion plasma

The impact of uncertainties in different parameters characterizing the plasma on the power deposition and the particle sources is analyzed and presented. The analysis focuses on the application of uncertainty quantification and sensitivity analysis (SA) to the neutral beam injection (NBI) by performing parametric modeling of the thermal equilibrium and the ionization process of the plasma. The uncertainties are propagated through the TAPaS code (Toroidal Accelerated PArticle Simulator), obtaining various quantities of interest, such as the birth profile of the NBI and the fraction of energy that is transferred to the ions and electrons of the background plasma. A non-intrusive, black-box approach is considered for the model responses through the utilization of a polynomial chaos expansion (PCE) as surrogate model. The global SA using the analytical computation of the Sobol indices from the estimated coefficients of the PCE allows to assign and rank the individual contribution of each uncertain parameter relative to the variation exhibited in the plasma heating. Further contributions from the interactions of different parameter combinations to the variance are also investigated.