Note: Measuring effects of Ar-ion cleaning on the secondary electron yield of copper due to electron impact

In a measurement system of total secondary electron yield (SEY) with in situ ion cleaning, we investigate SEY characteristics of the Cu samples cleaned at different Ar-ion energies and cleaning time. Measured SEY data are compared with those before cleaning and simulated with the Monte Carlo method for an ideal surface of copper. We find that weakening the cleaning intensity, i.e., the ion energy or cleaning time, in some circumstances, can further reduce both the maximum SEY and the SEY at the high-energy end (>0.3 keV) of primary electrons, though the SEY is increased somewhat at the low-energy end. Accompanied by the analysis on the opposing contributions of contamination elimination and surface morphology to the SEY, this study thus provides a comprehensive insight into the effects of ion cleaning on the SEY in the investigation and suppression of secondary electron emission.