Plasma Facing Component Characterization and Correlation With Plasma Conditions in Lithium Tokamak Experiment-<i>β</i>

Maan, A.; Ostrowski, E. T.; Kaita, R.; Donovan, David; Majeski, R.; Boyle, Dennis; Hughes, Paul L.; Merino, Enrique; Kozub, T.; Koel, Bruce E.; Elliott, Drew; Biewer, T. M.; Scotti, F.; Soukhanovskii, V.; Lunsford, R.

doi:10.1109/tps.2020.2969115

Cited by 17 publications

(14 citation statements)

References 17 publications

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“…[22] it was found the formation of lithium carbonate on the wall of HT-7 tokamak only after opening the tokamak vessel. In [23] it was proposed that the source of carbon for chemical reactions on the surface might be stainless steel. Li oxidized in experiments with injected lithium granules in EAST tokamak [35].…”

Section: Discussionmentioning

confidence: 99%

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Spectroscopic characterization of composite lithium materials irradiated with high-temperature plasma

Budaev

Fedorovich

Лубенченко

et al. 2020

Heliyon

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High-temperature plasma irradiation of materials leads to significant modification of surface structure, growth of deposited composite films and surface layers with induced self-similar granularity on the scale from macroscales to nanoscale due to strong plasma-surface interaction. The aim of this study was to characterize lithium materials irradiated with high-temperature plasma in the T-10 tokamak and PLM device. The reactivity of lithium leads to reactions with impurities in the plasma and on the vessel. Post-mortem analyses by the X-ray photoemission spectroscopy and X-ray analysis have been used to identify deposits composition and morphology. Lithium carbonate composites have been detected by analysis demonstrating materials mixing and evidence of plasmainduced structure. New structures with the high specific surface area of hierarchical granular are registered. The reference industrial powder of lithium carbonate irradiated with steady-state plasma in the PLM device has acquired a new similar structure demonstrating universal influence of plasma on the structure of irradiated materials.

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Section: Discussionmentioning

confidence: 99%

“…The additional source of carbon might be as well the atmospheric gases after opening the tokamak vessel as was observed in HT-7 tokamak, see [22]. The source of carbon might be as well stainless steel as discussed in [23].…”

Section: Experimental Samplesmentioning

confidence: 96%

Spectroscopic characterization of composite lithium materials irradiated with high-temperature plasma

Budaev

Fedorovich

Лубенченко

et al. 2020

Heliyon

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“…In particular, it can be flowed as a liquid which avoids permanent damage when exposed to instabilities like edge localized modes (ELMs) and disruptions. Lithium has also been seen to improve the performance of devices, which has been observed in several devices such as TFTR, NSTX, EAST, CDX-U and LTX [10][11][12][13][14]. This has been linked most closely to the fact that recycling, R, is reduced significantly.…”

Section: Introductionmentioning

confidence: 89%

First lithium experiments in HIDRA and evidence of helium retention during quasi-steady-state stellarator plasma operations

Andruczyk

Koyn

Allain

et al. 2022

Plasma Phys. Control. Fusion

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Experiments in HIDRA have had operational discharges between tdischarge = 60 – 1000 s using ECRH heating. This means that quasi-steady-state plasma discharges reach conditions to study long-pulse plasma material interactions. The HIDRA-MAT PMI diagnostic is used to place a drop of lithium onto a heated tungsten surface, transfer the sample in-vacuo and expose it in a helium plasma. Helium is of interest as there is an open question to whether lithium will be able to remove helium ash in real fusion devices. It was also observed that the plasma density and temperature increased by over 2.5 times. During lithium evaporation, as significant lithium ionization occurs, there is a 91% drop in the neutral pressure that is injected into the vessel, despite a constant flow of He gas. This is backed up by the fact that the helium neutral light intensity also drops. At one point in the discharge a lithium plasma is created, as indicated by an increase in Li+ emission and a complete reduction in He+ emission, but the electron density jumps from ne = 3×1018 m-3 to over ne = 8×1018 m-3 while the core temperature stays relatively constant between Te = 16 eV – 20 eV. Once the source of lithium is expired, residual Li and Li+ in the plasma maintain a low neutral He background which allows a He plasma to re-establish and be more efficiently heated. Here the density drops down to ne = 2×1018 m-3 and the electron temperature increases from Te = 20 eV to over Te = 50 eV. This is also indicated by the He+ emission re-establishing and having a higher intensity. In this paper we show the results from the first lithium campaign in HIDRA. In the presence of lithium, the helium disappears from the plasma via an as of yet unknown complex relationship that needs to be further studied.

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“…Flat temperature profiles were recently observed in LTX [3]. This temperature-gradient free regime was accessible with a low-recycling boundary of lithium coated PFCs [4,5]. * Author to whom any correspondence should be addressed.…”

Section: Introductionmentioning

confidence: 94%

Neutral beam prompt loss in LTX- β

Capecchi¹,

Anderson²,

Boyle³

et al. 2021

Nucl. Fusion

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Prompt loss of beam injected fast ions approaches 100% in lithium tokamak experiment-beta (LTX-β) discharges, though significantly improved confinement is expected for the higher current plasmas made available by a recent upgrade to the Ohmic heating power supply. Modeling of fast ions using TRANSP/NUBEAM finds a maximum coupled beam fraction of 76% at the near-term limits of the LTX-β operating space. The full ion orbit code POET is employed to validate NUBEAM results against possible non-adiabatic effects on fast ion orbits, but corrections to the prompt loss fraction due to collisionless transport are found to be small. The graphical method code CONBEAM is used to investigate the topology of fast ion phase space as it relates to neutral beam deposition, and counter-injected NBI is considered as a way to access a region of high field side beam deposition. A metric is developed within the CONBEAM using a beam filament model to estimate the prompt loss fraction and shown to agree well with both POET and NUBEAM, enabling near real-time analysis and potential feedback to operators between plasma discharges.

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Plasma Facing Component Characterization and Correlation With Plasma Conditions in Lithium Tokamak Experiment-β

Cited by 17 publications

References 17 publications

Spectroscopic characterization of composite lithium materials irradiated with high-temperature plasma

Spectroscopic characterization of composite lithium materials irradiated with high-temperature plasma

First lithium experiments in HIDRA and evidence of helium retention during quasi-steady-state stellarator plasma operations

Neutral beam prompt loss in LTX- β

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