In atmospheric RF discharges,a plenty of reactive oxygen species,which are very crucial for many applications,can be generated with He+O2 mixtures as working gas.By adjusting the oxygen impurities,the electronegativity of atmospheric plasmas could be changed,and the sheath dynamics become more complex with lots of negative ions produced.Under the given discharge conditions,the formation of electron peak density can be observed in the anode sheath region mainly due to the strong attachments(Fig.1),at the same time electric fields and electron temperature show different spatial distributions compared to the cases of weak attachments.