Physics design requirements for the National Spherical Torus Experiment liquid lithium divertor

Kugel, H.; Bell, M.G.; Berzak, L.; Brooks, A.; Ellis, R.; Gerhardt, S.; Harjes, H.C.; Kaita, R.; Kallman, J.; Maingi, R.; Majeski, R.; Mansfield, D. K.; Ménard, J.; Nygren, R.E.; Soukhanovskii, V.; Stotler, D.P.; Wakeland, P.; Zakharov, L.

doi:10.1016/j.fusengdes.2008.11.102

Cited by 39 publications

(27 citation statements)

References 9 publications

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“…Thus either a wider toroidal view or radial view of the liquid lithium divertor (LLD) 28 is possible, as shown in Figure N2-3. Here, the reported heat flux results used the radial view.…”

Section: N2 Diagnostic Preparationsmentioning

confidence: 99%

NSTX Report on FES Joint Facilities Research Milestone 2010

Maingi¹,

Ahn²,

Gray³

et al. 2011

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“…Thus either a wider toroidal view or radial view of the liquid lithium divertor (LLD) 28 is possible, as shown in Figure N2-3. Here, the reported heat flux results used the radial view.…”

Section: N2 Diagnostic Preparationsmentioning

confidence: 99%

NSTX Report on FES Joint Facilities Research Milestone 2010

Maingi¹,

Ahn²,

Gray³

et al. 2011

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“…It is described in detail in refs. [5] and [31]. The Langmuir probe array used for this study is situated in between toroidal segments of the LLD and has been described elsewhere as well [7,8].…”

Section: Apparatus and Approachmentioning

confidence: 99%

“…The Liquid Lithium Divertor (LLD) was installed and tested in NSTX in order to provide an initial assessment of a porous molybdenum plasma-facing component with evaporated lithium coatings and the associated plasmamaterial interactions (PMI) [5,6]. In addition to the extensive core diagnostics available on NSTX, new divertor diagnostics were installed alongside the LLD [7,8].…”

Section: Introductionmentioning

confidence: 99%

Modification Of The Electron Energy Distribution Function During Lithium Experiments On The National Spherical Torus Experiment

Jaworski¹,

Gray²,

Kaita³

et al. 2011

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The National Spherical Torus Experiment (NSTX) has recently studied the use of a liquid lithium divertor (LLD). Divertor Langmuir probes have also been installed for making measurements of the local plasma conditions. A non-local probe interpretation method is used to supplement the classical probe interpretation and obtain measurements of the electron energy distribution function (EEDF) which show the occurrence of a hot-electron component. Analysis is made of two discharges within a sequence that exhibited changes in plasma fueling efficiency. It is found that the local electron temperature increases and that this increase is most strongly correlated with the energy contained within the hot-electron population. Preliminary in- scrape-off layer (SOL) plasma. The decrease in plasma fueling efficiency, increase in local temperature, and increase in hot-electron fraction are all consistent with an absorbing surface intercepting the SOL plasma.

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“…Experiments in T11-M at TRINITI, Troitsk, Moscow 13 the Current Drive eXperiment -Upgrade (CDX-U, at PPPL), 3 and the Frascati Tokamak Upgrade (FTU, at ENEA Frascati) 14 have all employed liquid lithium as a PFC, to varying degrees. Near-term experiments in the Lithium Tokamak eXperiment (LTX, at PPPL) 15 and NSTX 16 will make more extensive use of liquid lithium PFCs. Lithium would not be a serious candidate for a liquid metal PFC, due to its low operating temperature limit, if it did not offer the possibility of very low recycling.…”

Section: Liquid Metals For Pfcsmentioning

confidence: 99%

“…Beneficial effects observed on FTU during lithium experiments include a reduction in the plasma Z-effective, and an extension of the operational plasma density window somewhat beyond the Greenwald limit. Porous metallic systems to retain liquid lithium have also now been installed in NSTX 16 at PPPL, although the NSTX approach employs a porous plasma-sprayed molybdenum surface rather than layers of molybdenum mesh. The use of plasma sprayed porous metal technology was developed for the LTX device at PPPL, and is applicable to large-area surfaces with complex shapes.…”

Section: Lithium Wall Conditioning and Liquid Lithium Pfc Experimentsmentioning

confidence: 99%

Liquid Metal Walls, Lithium, And Low Recycling Boundary Conditions In Tokamaks

Majeski¹

2010

AIP Conference Proceedings

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Abstract. At present, the only solid material believed to be a viable option for plasma-facing components (PFCs) in a fusion reactor is tungsten. Operated at the lower temperatures typical of present-day fusion experiments, tungsten is known to suffer from surface degradation during long-term exposure to helium-containing plasmas, leading to reduced thermal conduction to the bulk, and enhanced erosion. Existing alloys are also quite brittle at temperatures under 700°C. However, at a sufficiently high operating temperature (700 -1000 °C), tungsten is selfannealing and it is expected that surface damage will be reduced to the point where tungsten PFCs will have an acceptable lifetime in a reactor environment.The existence of only one potentially viable option for solid PFCs, though, constitutes one of the most significant restrictions on design space for DEMO and follow-on fusion reactors. In contrast, there are several candidates for liquid metal-based PFCs, including gallium, tin, lithium, and tin-lithium eutectics. We will discuss options for liquid metal walls in tokamaks, looking at both high and low recycling materials. We will then focus in particular on one of the candidate liquids, lithium.Lithium is known to have a high chemical affinity for hydrogen, and has been shown in test stands 1 and fusion experiments 2,3 to produce a low recycling surface, especially when liquid. Because it is also low-Z and is usable in a tokamak over a reasonable temperature range (200 -400 °C), it has been now been used as a PFC in several confinement experiments (TFTR, T11-M, CDX-U, NSTX, FTU, and TJ-II), with favorable results. The consequences of substituting low recycling walls for the traditional high recycling variety on tokamak equilibria are very extensive. We will discuss some of the expected modifications, briefly reviewing experimental results, and comparing the results to expectations.

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Physics design requirements for the National Spherical Torus Experiment liquid lithium divertor

Cited by 39 publications

References 9 publications

NSTX Report on FES Joint Facilities Research Milestone 2010

NSTX Report on FES Joint Facilities Research Milestone 2010

Modification Of The Electron Energy Distribution Function During Lithium Experiments On The National Spherical Torus Experiment

Liquid Metal Walls, Lithium, And Low Recycling Boundary Conditions In Tokamaks

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