Spreading of lithium on a stainless steel surface at room temperature

Authors:  C. H. Skinner, A.M. Capece, J.P. Roszell, B. E. Koel


Abstract:  Lithium conditioned plasma facing surfaces have lowered recycling and enhanced plasma performance on many fusion devices and liquid lithium plasma facing components are under consideration for future machines. A key factor in the performance of liquid lithium components is the wetting by lithium of its container. We have observed the surface spreading of lithium from a mm-scale particle to adjacent stainless steel surfaces using a scanning Auger microprobe that has elemental discrimination. The spreading of lithium occurred at room temperature (when lithium is a solid) from one location at a speed of 0.62 μm/day under ultrahigh vacuum conditions. Separate experiments using temperature programmed desorption (TPD) investigated bonding energetics between monolayer-scale films of lithium and stainless steel. While multilayer lithium desorption from stainless steel begins to occur just above 500 K (Edes=1.54 eV), sub-monolayer Li desorption occurred in a TPD peak at 942 K (Edes=2.52 eV) indicating more energetically favorable lithium-stainless steel bonding (in the absence of an oxidation layer) than lithium-lithium bonding.
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Submitted to:  Journal of Nuclear Materials
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Download PPPL-5216 (pdf 4.3 MB 21 pp)
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