Surface modifications of fusion reactor relevant materials on exposure to fusion grade plasma in plasma focus device

• Published in: Applied surface science Vol. 355; pp. 989 - 998
• Main Authors: Niranjan, Ram, Rout, R.K., Srivastava, R., Chakravarthy, Y., Mishra, P., Kaushik, T.C., Gupta, Satish C.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.11.2015
• Subjects: Blisters; Devices; Erosion; Exposure; Fusion reactors; Irradiation; Micro-cracks; Plasma focus; Plasma focus discharge; Scanning electron microscopy; Stainless steels; Surface layer; X-rays; Blisters; Irradiation; Micro-cracks; Plasma focus discharge; Erosion
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2015.07.192

•Exposure of materials (W, Ni, SS, Mo and Cu) to fusion plasma in a plasma focus device.•The erosion and the formations of blisters, pores, craters, micro-cracks after irradiation.•The structural phase transformation in the SS sample after irradiation.•The surface layer alloying of the samples with the plasma focus anode material. An 11.5kJ plasma focus (PF) device was used here to irradiate materials with fusion grade plasma. The surface modifications of different materials (W, Ni, stainless steel, Mo and Cu) were investigated using various available techniques. The prominent features observed through the scanning electron microscope on the sample surfaces were erosions, cracks, blisters and craters after irradiations. The surface roughness of the samples increased multifold after exposure as measured by the surface profilometer. The X-ray diffraction analysis indicated the changes in the microstructures and the structural phase transformation in surface layers of the samples. We observed change in volumes of austenite and ferrite phases in the stainless steel sample. The energy dispersive X-ray spectroscopic analysis suggested alloying of the surface layer of the samples with elements of the PF anode. We report here the comparative analysis of the surface damages of materials with different physical, thermal and mechanical properties. The investigations will be useful to understand the behavior of the perspective materials for future fusion reactors (either in pure form or in alloy) over the long operations.