Thermal shock behaviour of blisters on W surface during combined steady-state/pulsed plasma loading. (24th September 2015)

• Record Type: Journal Article
• Authors: Jia, Y.Z.; Liu, W.; Xu, B.; Luo, G.-N.; Li, C.; Qu, S.L.; Morgan, T.W.; De Temmerman, G.
• Is Part Of: Nuclear fusion. Volume 55:Number 11(2015:Nov.)
• Publication Date: 2015-09-24
• Subjects: blister -- crack -- tungsten -- ELMs -- pulsed plasma; Nuclear fusion -- Periodicals; 621.48405
• DOI: 10.1088/0029-5515/55/11/113015
• Languages: English
• ISSNs: 0029-5515

Abstract

Abstract: The thermal shock behaviour of blister-covered W surfaces during combined steady-state/pulsed plasma loading was studied by scanning electron microscopy and electron backscatter diffraction. The W samples were first exposed to steady-state D plasma to induce blisters on the surface, and then the blistered surfaces were exposed to steady-state/pulsed plasma. Growth and cracking of blisters were observed after the exposure to the steady-state/pulsed plasma, while no obvious damage occurred on the surface area not covered with blisters. The results confirm that blisters induced by D plasma might represent weak spots on the W surface when exposed to transient heat load of ELMs. The cracks on blisters were different from the cracks due to the transient heat loads reported before, and they were assumed to be caused by stress and strain due to the gas expansion inside the blisters during the plasma pulses. Moreover, most of cracks were found to appear on the blisters formed on grains with surface orientation near [1 1 1].