Flowing liquid lithium plasma-facing components – Physics, technology and system analysis of the LiMIT system

Ruzic, D. N.; Szott, Matthew; Sandoval, C.; Christenson, Michael; Fiflis, P.; Hammouti, Sabrina; Kalathiparambil, Kishor; Shchelkanov, Ivan; Andruczyk, Daniel; Stubbers, R.; Foster, C. Joel; Jurczyk, Brian E.

doi:10.1016/j.nme.2017.06.001

Cited by 20 publications

(9 citation statements)

References 18 publications

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“…This behaviour is confirmed by more than 10 years of simulations, laboratory and in-situ experiments summarized in [3]. Enhanced confinement features observed under extensive lithium wall coverage [1,8] and the numerous application of lithium in Tokamaks and Stellarators [9][10][11] make lithiumization a popular wall conditioning alternative.…”

Section: Introductionmentioning

confidence: 59%

Boron synergies in lithium film performance

Devitre

Oyarzábal²,

Fernández-Berceruelo³

et al. 2020

Nucl. Fusion

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Fusion experiments use lithium and boron getters to capture impurities and control the density of fuel species in the plasma. In the TJ-II Stellarator, the addition of a boron-carbon substrate was found to extend the lifetime of the very reactive lithium wall conditioning. However, the synergies between the lithium layer and the underlying boron-carbon, or the effect of a glow discharge cleaning, on oxygen and deuterium gettering are not fully understood. Laboratory experiments were therefore initiated to gain deeper insight on the getter properties of B(C)/Li walls. The coatings were exposed to oxygen gas and plasmas while the capture and release of O was followed by mass spectrometry. Without the boron substrate, the maximum oxygen uptake is half the number of lithium atoms in the film for both oxygen gas and oxygen plasma. Conversely, the behaviour of B(C)/Li walls depends on the nature of the oxidation process: molecular oxygen (O:Li ≈ 0.15) or plasma (O:Li ≈ 0.50). The oxygen plasma gettering is thus preserved against molecular oxidation, e.g. an overnight exposure to the residual gas. While oxygen is known to promote hydrogen retention in lithium, the oxygen content of a B(C)/Li coating shows little effect on deuterium retention. Unlike simple lithium, the oxygen and deuterium gettering of B(C)/Li recovers after a helium glow discharge treatment. These advantageous features clearly point to a change in chemistry, with complex interactions between film constituents and the oxygen-rich environment of magnetic fusion devices.

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Section: Introductionmentioning

confidence: 59%

Boron synergies in lithium film performance

Devitre

Oyarzábal²,

Fernández-Berceruelo³

et al. 2020

Nucl. Fusion

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“…A method to produce a structure capable of promoting the wicking of liquid metals, is to machine narrow channels with widths on the scale of tens of microns into the surface of the PFC. Laser micro machining is one of the means employed to produce these features with minimal impact on the underlying high temperature and structural material properties [8,9].…”

Section: Introductionmentioning

confidence: 99%

Wetting and spreading of liquid lithium onto nanocolumnar tungsten coatings tailored through the topography of stainless steel substrates

et al. 2020

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The use of liquid metal as an alternative to cover the plasma-exposed areas of fusion reactors has called for the development of substrates where refilling and metal spreading occur readily and at reasonably low temperatures. In the search for common materials for this purpose, we show that nanostructured tungsten coatings deposited on stainless steel (SS) by magnetron sputtering at oblique angles (MS-OAD) is a good option, provided that the surface microstructure of substrate is properly engineered. Tungsten thin films with nominal thicknesses of 500 and 2500 nm were deposited onto SS plates subjected to conventional surface finishing treatments (sand blasting, sand paper abrasion and electrochemical polishing) to modify the surface topography and induce the appearance of different groove patterns. In the first part of this work we show how the topographical features of the SS substrates affect the typical nanocolumnar microstructure of OAD thin films of tungsten. Subsequently, we characterize the spreading behavior of liquid lithium onto these tungsten nanocolumnar surfaces and critically discuss whether nanocolumnar tungsten thin films are a suitable option for the wetting and spreading of molten lithium. As a result, we reveal that the features of the tungsten nanocolumnar coating, characterized by a given height and void spaces between nanocolumns in the order of 1-2 µm, is critical for the spreading of molten lithium, while the existence of wider channels affects it very weakly. Moreover, it is shown that tungsten films deposited by MS-OAD on SS substrates subjected to conventional finishing procedures represent a good alternative to other more complex surface engineering procedures utilized for this purpose.

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“…In this case Li acts as a pump for hydrogenic species, and therefore fuel recovery can take place by purification of the circulating LM. These concepts are very promising, even though the level of maturity in terms of robust power handling is lower with respect to slow-flow concepts [18].…”

Section: Introductionmentioning

confidence: 99%

Self-consistent modelling of a liquid metal box-type divertor with application to the divertor tokamak test facility: Li versus Sn

et al. 2019

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In the present work a model for a liquid metal (LM) box-type divertor is presented, aimed at including the most relevant aspects of its rich physics, as well as some engineering elements. Given the upstream plasma conditions and for a fixed divertor geometry, the model selfconsistently evaluates the plasma heat and particle flux on the LM surface, the thermodynamic state of the metal (liquid and vapor) in the divertor boxes and the temperature distribution in the solid walls. The model is then applied to the divertor tokamak test facility, which is currently being designed in Italy, comparing Li and Sn as possible LM choices, in terms of operating temperatures and of metal vapor flux from the divertor box system towards the main plasma chamber.

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Flowing liquid lithium plasma-facing components – Physics, technology and system analysis of the LiMIT system

Cited by 20 publications

References 18 publications

Boron synergies in lithium film performance

Boron synergies in lithium film performance

Wetting and spreading of liquid lithium onto nanocolumnar tungsten coatings tailored through the topography of stainless steel substrates

Self-consistent modelling of a liquid metal box-type divertor with application to the divertor tokamak test facility: Li versus Sn

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