GRAPHITE SURFACE DESTRUCTION UNDER PLASMA ION AND OXYGEN GAS IRRADIATION

In this paper we describe the erosion and surface relief transformation of MPG-8 type graphite, as well as the sputtering properties of B4C and of the modified carbonic fibre material, KUP-VM + 5 at% TiC, under He+ and He+/O2 irradiation. Experiments were carried out in a gas discharge. We found an increase of the erosion rate of MPG-8 surface under He+/O2 bombardment, along with a growth of the incoming O2 flux in the range (0.5-2.0) x 10(16) mol O2 cm2 s. At T = 1200 K the sputtering yield of MPG-8 (He+/O2, j(o)2 = 1 x 10(16) mol O2/cm2 s) reached S = 1.6 at/ion. The relative increase of the MPG-8 sputtering yield in the presence of oxygen was much higher than that of B4C and KUP-VM + 5 at% TiC. On the MPG-8 surface, irradiated both by He+/O2 and O2 beams, porosity was observed.