Chapter 9: The FTU Machine - Design Construction and Assembly

Pizzuto, A.; Annino, C.; Baldarelli, M.; Bettinali, L.; Brolatti, G.; Crescenzi, C.; Maddaluno, G.; Riccardi, B.; Righetti, Giulia; Roccella, M.; Semeraro, L.

doi:10.13182/fst04-a523

Cited by 6 publications

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“…This can be explained by the austenite-to-ferrite phase transformation that occurs in re-solidified spherical droplets and splashes when embedded in a strong magnetic field environment [8]. In addition, the FTU spectrum reveals the probable presence of martensite, typical of rapid cooling down of molten grains, a peculiarity that can be attributed to the fact that FTU is a cryogenic device [21,22].…”

Section: Analysis Of Magnetic Dustmentioning

confidence: 99%

Cross machine investigation of magnetic tokamak dust: Morphological and elemental analysis

Angeli

Ripamonti

Ghezzi

et al. 2021

Fusion Engineering and Design

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The presence of magnetic dust can be an important issue for future fusion reactors where plasma breakdown is critical. Magnetic dust has been collected from contemporary fusion devices (FTU, Alcator C-Mod, COMPASS and DIII-D) that feature different plasma facing components. The results of morphological and elemental analysis are presented. Magnetic dust is based on steel or nickel alloys and its magnetism is generated by intense plasma-material interactions. In spite of the strong similarities in terms of morphology and composition, X-ray diffraction analysis revealed differences in the structural evolution that leads to non-trivial magnetic responses.

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Section: Analysis Of Magnetic Dustmentioning

confidence: 99%

Cross machine investigation of magnetic tokamak dust: Morphological and elemental analysis

Angeli

Ripamonti

Ghezzi

et al. 2021

Fusion Engineering and Design

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“…FTU is a full metal compact tokamak, with toroidal and poloidal limiters made by TZM Mo alloy, that is designed to work with a toroidal magnetic field up to 8 T and high plasma densities [20]. The poloidal limiter is mounted on the equatorial plane of port P1, at the low field side, while the toroidal limiter is located at the high field side, all around the torus, at the equatorial plane.…”

Section: Post-mortem Observationsmentioning

confidence: 99%

Evidence for high-velocity solid dust generation induced by runaway electron impact in FTU

et al. 2022

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Post-mortem and in-situ evidence is presented in favor of the generation of high-velocity solid dust during the explosion-like interaction of runaway electrons with metallic plasma-facing components in FTU. The freshly-produced solid dust is the source of secondary de-localized wall damage through high-velocity impacts that lead to the formation of craters, which have been reproduced in dedicated light gas gun impact tests. This novel mechanism, of potential importance for ITER and DEMO, is further supported by surface analysis, multiple theoretical arguments and dust dynamics modelling.

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“…Therefore the gain of a deeper knowledge on dust characteristics and its production mechanisms, and comparison with dust collected from different tokamaks, is of high interest. From this point of view, the study of the dust accumulation in FTU (Frascati Tokamak Upgrade) is particularly significant since this tokamak has the exclusive characteristic of having been in operation with a full metal wall (kept at cryogenic temperature by the use of liquid nitrogen cooling) during its entire life [8]; moreover FTU is also equipped with a liquid lithium limiter (LLL) since 2005. As shown for other tokamaks [9][10][11][12][13][14][15], dust production depends, in terms of composition and size, on the material used for plasma facing components (PFCs) and on the history of each single machine.…”

Section: Introductionmentioning

confidence: 99%

Investigation on FTU dust and on the origin of ferromagnetic and lithiated grains

et al. 2015

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A comprehensive analysis of composition and morphology of metallic micrometric particles collected in FTU during the 2013 shut-down is presented. The data-set analyzed is the result of years of experimental activity in FTU which is a full metal machine since the beginning of operation and with a liquid lithium limiter (LLL) from 2005. It was found that the metallic population, consisting of flakes, smashed and spheroidally shaped particles from plasma facing components (mainly SS and Mo), exhibits an unexpectedly high, up to 70 wt%, fraction of magnetic grains. The change of crystalline phase from γ to α/δ of the iron component contained in the particles coming from stainless steel is suggested as the mechanism responsible for magnetic dust production. This phase change can be ascribed to the particle temperature quench and/or to the presence of a strong magnetic field during the re-solidification of molten stainless steel droplets. In connection to the dust collected close to the LLL, consisting mainly of lithium carbonate spherical-like particles up to a few mm, the mechanism of Li 2 CO 3 formation and its role as a source of C and O impurities are discussed.

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Chapter 9: The FTU Machine - Design Construction and Assembly

Cited by 6 publications

References 0 publications

Cross machine investigation of magnetic tokamak dust: Morphological and elemental analysis

Cross machine investigation of magnetic tokamak dust: Morphological and elemental analysis

Evidence for high-velocity solid dust generation induced by runaway electron impact in FTU

Investigation on FTU dust and on the origin of ferromagnetic and lithiated grains

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