Sensitivity analysis of the particle in cell (PIC) code hPIC for near surface plasma conditions.

Sensitivity Analysis (SA) and Uncertainty Quantification (UQ) are used to assess and improve physics models. After assessing the uncertainties produced by input parameters, the next logical step is to carry out sensitivity analysis to ensure both robustness of the code over a wide range of plasma conditions (input parameters) and help understanding the underlying physics. In this work, several methods of sensitivity analysis were used to quantify the sensitivity of the Ion Energy Angle Distributions (IEADs) at the plasma sheath edge. The sensitivity analysis methods utilized include One At a Time (OAT) for local sensitivity analysis and Morris screening and variance decomposition (Sobol indices) for global sensitivity analysis. The particle in cell (PIC) code utilized for the analysis is hPIC. Due to the high computational cost of PIC simulations a surrogate model has been developed and used to generate samples for the sensitivity analysis. The global sensitivity analysis showed that the electron temperature has the most impact on the IEADs followed by the ion temperature and magnetic field inclination angle.