TY  - JOUR
AU  - Sinclair, G.
AU  - Tripathi, J. K.
AU  - Diwakar, P. K.
AU  - Linke, J.
AU  - Hassanein, A.
AU  - Wirtz, Marius
TI  - Structural evolution of tungsten surface exposed to sequential low-energy helium ion irradiation and transient heat loading
JO  - Nuclear materials and energy
VL  - 12
SN  - 2352-1791
CY  - Amsterdam [u.a.]
PB  - Elsevier
M1  - FZJ-2018-02222
SP  - 405 - 411
PY  - 2017
AB  - 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.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000417293300061
DO  - DOI:10.1016/j.nme.2017.03.003
UR  - https://juser.fz-juelich.de/record/844876
ER  -