Microscopic evolution of pre-damaged and undamaged tungsten exposed to low-energy and high-flux helium ions

• Published in: Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms Vol. 325; pp. 73 - 78
• Main Authors: Yang, Qi, Liu, Dongping, Fan, Hongyu, Li, Xin, Niu, Jinhai, Wang, Younian
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.04.2014
• Subjects: Conductive atomic force microscopy; He bubbles; Irradiation; Conductive atomic force microscopy; Irradiation; He bubbles
• ISSN: 0168-583X; 1872-9584
• DOI: 10.1016/j.nimb.2014.02.011

High-energy (260keV) He+ pre-damaged and undamaged polycrystalline tungsten samples were irradiated with low-energy (220eV) and high-flux (∼1021ions/m2s) He+ at a sample temperature of 873K to a fluence of 1.0×1025ions/m2. Microscopic evolution of these samples was carried out using non-destructive conductive atomic force microscopy and a nanohardness test. Analysis indicates that a large number of nanometer-sized protuberances of irradiated tungsten samples results from over-high internal pressure of nanometer-sized helium bubbles. Ordered and nanostructured helium bubbles with the same diameter and average spacing can be formed due to the self-trapping and self-organizing of helium atoms in the tungsten materials. In the case of pre-damaged, low-energy He+ irradiation results in a random distribution of nanostructured helium bubbles, indicating that high-energy He+ implantation results in serious irradiation damage of tungsten materials, acting as nuclei for helium bubbles.