%0 Journal Article
%A Sinclair, G.
%A Tripathi, J. K.
%A Diwakar, P. K.
%A Linke, J.
%A Hassanein, A.
%A Wirtz, Marius
%T Structural evolution of tungsten surface exposed to sequential low-energy helium ion irradiation and transient heat loading
%J Nuclear materials and energy
%V 12
%@ 2352-1791
%C Amsterdam [u.a.]
%I Elsevier
%M FZJ-2018-02222
%P 405 - 411
%D 2017
%X Structural damage due to high flux particle irradiation can result in significant changes to the thermal strength of the plasma facing component surface (PFC) during off-normal events in a tokamak. Low-energy He+ ion irradiation of tungsten (W), which is currently the leading candidate material for future PFCs, can result in the development of a fiber form nanostructure, known as “fuzz”. In the current study, mirror-finished W foils were exposed to 100 eV He+ ion irradiation at a fluence of 2.6 × 1024 ions m−2 and a temperature of 1200 K. Then, samples were exposed to two different types of pulsed heat loading meant to replicate type-I edge-localized mode (ELM) heating at varying energy densities and base temperatures. Millisecond (ms) laser exposure done at 1200 K revealed a reduction in fuzz density with increasing energy density due to the conglomeration and local melting of W fibers. At higher energy densities (∼ 1.5 MJ m−2), RT exposures resulted in surface cracking, while 1200 K exposures resulted in surface roughening, demonstrating the role of base temperature on the crack formation in W. Electron beam heating presented similar trends in surface morphology evolution; a higher penetration depth led to reduced melt motion and plasticity. In situ mass loss measurements obtained via a quartz crystal microbalance (QCM) found an exponential increase in particle emission for RT exposures, while the prevalence of melting from 1200 K exposures yielded no observable trend.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000417293300061
%R 10.1016/j.nme.2017.03.003
%U https://juser.fz-juelich.de/record/844876