Interaction of powerful hot plasma and fast ion streams with materials in dense plasma focus devices

Damage study of irradiated tungsten and copper using proton and argon ions of a plasma focus device

The destructive effects of proton and argon ions produced in a low energy plasma focus device on the surface of tungsten and copper were investigated. Optical microscopy, SEM, EDX, XRD and ERD analysis were performed for initial and irradiated samples. The results showed that total thermal impact under the irradiation by argon is much more significant than that by hydrogen. Sub-micrometer blisters, clusters of joined bubbles and rupture patterns were observed on the surface of copper after irradiation by argon. Micro-cracks were observed on the tungsten samples irradiated by argon, which indicate fast annealing of the molten surface. Many dense blisters and evidence of ion sputtering were observed on the surfaces irradiated by protons. Results of ERD analysis showed that the highest concentration of hydrogen is 24% in the second layer and at a depth of 20-55 nm from the tungsten surface. In the copper sample, the highest density of hydrogen was found to be 23% in the second layer and at a depth of 28-68 nm. Also, the highest penetration depth of protons into the tungsten and copper samples was 118 nm and 160 nm, respectively.