Erosion of tungsten surfaces in He and Ar/He plasma

Irradiation tests of tungsten surface were performed with He and He/Ar plasma generated by microwave electron cyclotron resonance. Thickness loss was used as the erosion rate of tungsten surface under the plasma irradiation. The results revealed that the thickness loss increased linearly with negative bias. SEM images proved that the addition of Ar apparently increased the plasma erosion. The thickness loss increased sharply with the Ar fraction of Ar/He mixture when it was 〈20 %,where the increasing slope of thickness loss lowered down gradually.