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Isolated nano-tendril bundles on tungsten surfaces exposed to radiofrequency helium plasma

2017; Elsevier BV; Volume: 12; Linguagem: Inglês

10.1016/j.nme.2017.04.016

2352-1791

Kevin B. Woller, D.G. Whyte, G.M. Wright,

Ion-surface interactions and analysis

The DIONISOS experiment is used to study the impact of RF helium (He) plasma on the surface morphology of tungsten (W) at a frequency of 13.56 MHz. Helium ion energy distributions with a span of 70–75 eV, while still below the sputtering threshold result in nano-tendril bundles (NTBs) and free-standing W whiskers on surfaces at 1020 K. The NTBs are distributed intragranularly with coverage of less than 10% while reaching up to 30 µm normal to the surface for He ion fluence of 7.6 × 1025 m−2 and flux density of 1022 m−2 s−1. Analysis of the NTB interior and sub-surface structure is provided through focused ion beam cross section.