Numerical Error Analysis of EMC3-EIRENE Simulations on HSX

Plasma edge simulations with codes like EMC3-EIRENE are designed to study 3D magnetic confinement devices. However, numerical errors can significantly impact simulation fidelity and are often insufficiently characterized. In this work, we analyze these error contributions in EMC3-EIRENE simulations of the quasi-helically symmetric (QHS) configuration of the Helically Symmetric eXperiment (HSX). These errors consist of the time integration error due to finite numerical timesteps, the bias and statistical error due to only following finite Monte Carlo particles, and the discretization error due to a finite grid resolution. Dependency between simulations is observed, affecting error reduction of statistical averaging. Key plasma quantities are examined across magnetic geometry to identify error trends and local sensitivity. Error reduction rates are evaluated against theoretical expectations. While the time integration error and statistical error generally follow predicted scaling, the bias error exhibits weaker correlation with theoretical reduction rates. Additionally, we identify regimes where certain numerical parameters lead to unphysical behavior and numerical instability. These results provide guidance for improving accuracy and efficiency in plasma edge modeling of stellarators with EMC3-EIRENE.