The lifetime of gridded ion engines is primarily limited by erosion of the ion optics system. Despite extensive research, the availability of quantitative, spatially resolved erosion data under long-duration operation remains limited, particularly for internal erosion features such as aperture barrel erosion. This work presents a quantitative characterisation of erosion in a three-grid ion optics system using a combination of scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDX) and micro-computed tomography (micro-CT). The micro-CT approach, previously explored in preparatory studies within the same programme frame, is here applied to enable non-destructive, volumetric assessment of eroded ion optics after longduration operation. A dedicated experimental design incorporating three distinct aperture regions within a single ion optics system allows direct comparison of erosion behaviour under identical plasma and facility conditions during a 1000h endurance test with xenon propellant. Erosion characterisation was performed at multiple time points (0, 100, 500, and 1000h), combining surface and volumetric diagnostics to resolve both edge and barrel erosion processes. The results show consistent trends in erosion behaviour across different aperture regions, indicating a systematic dependence on local geometry. Quantitative analysis reveals distinct erosion modes, including significant barrel erosion and configuration-dependent edge evolution. SEM–EDX analysis confirms inter-grid material transfer, while no redeposition of facility materials was detected above the sensitivity limits of the method. The combined diagnostic approach is validated by the consistency between SEM and micro-CT observations, demonstrating its capability for non-destructive, quantitative assessment of ion-optics erosion. The presented results establish a highfidelity baseline dataset and provide experimental insight into erosion mechanisms and material transport within the extraction region under realistic operating conditions.     «

The lifetime of gridded ion engines is primarily limited by erosion of the ion optics system. Despite extensive research, the availability of quantitative, spatially resolved erosion data under long-duration operation remains limited, particularly for internal erosion features such as aperture barrel erosion. This work presents a quantitative characterisation of erosion in a three-grid ion optics system using a combination of scanning electron microscopy with energy-dispersive X-ray spectroscopy...     »