The impact of the ITER-like wall at JET on disruptions

Vries, P. C. de; Arnoux, G.; Huber, A.; Flanagan, J.; Lehnen, M.; Riccardo, V.; Reux, C.; Jachmich, S.; Lowry, C.; Calabrò, G.; Frigione, D.; Tsalas, M.; Hartmann, N.; Brezinsek, S.; Clever, M.; Douai, D.; Groth, M.; Hender, T. C.; Hodille, E.; Joffrin, E.; Kruezi, U.; Matthews, G. F.; Morris, J.; Neu, R.; Philipps, V.; Sergienko, G.; Sertoli, M.; Contributors, Jet

doi:10.1088/0741-3335/54/12/124032

Cited by 74 publications

(73 citation statements)

References 33 publications

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“…Correlation with disruption force reveals that the number of detected dust particles increases strongly with disruption force (figure 3) and confirms the results shown in [10]. Moreover, it indicates that disruptions may stir-up dust particles present in the machine.…”

Section: Jet-c Jet-ilw X 30supporting

confidence: 86%

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Transient impurity events in JET with the new ITER-like wall

et al. 2014

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Abstract. Transient impurity events leading to unexpected increase in radiated power have been studied in JET from the installation of the ITER-like wall. A total of 1800 events over 2800 plasma discharges have been detected. None have led to permanent changes in plasma conditions. Of all events 60% show traces of W, 25% of either Ni, Fe or Cr from either Inconel or steel structures. They occur mainly in diverted magnetic configuration, independently of strike-point position. The effect of disruptions on dust redistribution has been investigated using the Thomson scattering diagnostic and correlated with TIE occurrence. The number of dust events detected increases with disruption force and, in comparison to the full-C wall, the amount of dust mobilized is found to be about an order of magnitude lower. Their time evolution correlates well with that of the transient impurity events.PACS numbers:

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Section: Jet-c Jet-ilw X 30supporting

confidence: 86%

“…For each event, the elements responsible have been analysed using two VUV spectrometers, measuring respectively in range [10,100] nm and close to 5 nm. The first one measures spectral lines of Ni, Fe, Cr, Al and Cu, and can provide an indication of tungsten.…”

Section: Geometrical Dependencies and Impurity Identificationmentioning

confidence: 99%

Transient impurity events in JET with the new ITER-like wall

et al. 2014

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“…This results in a higher fraction of the energy to be conducted to the place facing components and also increases the current quench duration. The latter enhances the impulse exerted by the disruption on the vessel and could results in high vertical excursions of the vessel [26].…”

Section: Development Of the H-mode Baseline Scenario At I P = 35mamentioning

confidence: 99%

First scenario development with the JET new ITER-like wall

Joffrin

Baruzzo²,

Beurskens

et al. 2013

Nucl. Fusion

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In the recent JET experimental campaigns with the new ITER-like wall (JET-ILW), major progress has been achieved in the characterization and operation of the H-mode regime in metallic environments: (i) plasma breakdown has been achieved at the first attempt and X-point L-mode operation recovered in a few days of operation; (ii) stationary and stable type-I ELMy H-modes with βN ∼ 1.4 have been achieved in low and high triangularity ITER-like shape plasmas and are showing that their operational domain at H = 1 is significantly reduced with the JET-ILW mainly because of the need to inject a large amount of gas (above 1022 D s−1) to control core radiation; (iii) in contrast, the hybrid H-mode scenario has reached an H factor of 1.2–1.3 at βN of 3 for 2–3 s; and, (iv) in comparison to carbon equivalent discharges, total radiation is similar but the edge radiation is lower and Zeff of the order of 1.3–1.4. Strong core radiation peaking is observed in H-mode discharges at a low gas fuelling rate (i.e. below 0.5 × 1022 D s−1) and low ELM frequency (typically less than 10 Hz), even when the tungsten influx from the diverter is constant. High-Z impurity transport from the plasma edge to the core appears to be the dominant factor to explain these observations. This paper reviews the major physics and operational achievements and challenges that an ITER-like wall configuration has to face to produce stable plasma scenarios with maximized performance.

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“…The ITER-like Wall had a significant impact on disruption physics at JET [26]. The strongreduction of the C concentration seen from the very first ILW discharges had two direct consequences.…”

Section: Disruption Behaviourmentioning

confidence: 99%

First operation with the JET International Thermonuclear Experimental Reactor-like wall

et al. 2013

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AbstrAct.To consolidate ITER design choices and prepare for its operation, JET has implemented ITER's plasma facing materials, namely Be at the main wall and W in the divertor. In addition, protection systems, diagnostics and the vertical stability control were upgraded and the heating capability of the neutral beams was increased to over 30 MW. First results confirm the expected benefits and the limitations of all metal plasma facing components (PFCs), but also yield understanding of operational issues directly relating to ITER. H-retention is lower by at least a factor of 10 in all operational scenarios compared to that with C PFCs. The lower C content (Section 1factor 10) have led to much lower radiation during the plasma burn-through phase eliminating breakdown failures.Similarly, the intrinsic radiation observed during disruptions is very low, leading to high power loads and to a slow current quench. Massive gas injection using a D 2 /Ar mixture restores levels of radiation and vessel forces similar to those of mitigated disruptions with the C wall. Dedicated L-H transition experiments indicate a reduced power threshold by 30%, a distinct minimum density and pronounced shape dependence. The L-mode density limit was found up to 30% higher than for C allowing stable detached divertor operation over a larger density range. Stable H-modes as well as the hybrid scenario could be only re-established when using gas puff levels of a few 10 21 es −1. On average the confinement is lower with the new PFCs, but nevertheless, H factors up to 1 (H-Mode) and 1.3 (at b N ≈ 3, hybrids) have been achieved withWconcentrationswell below themaximum acceptable level.

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The impact of the ITER-like wall at JET on disruptions

Cited by 74 publications

References 33 publications

Transient impurity events in JET with the new ITER-like wall

Transient impurity events in JET with the new ITER-like wall

First scenario development with the JET new ITER-like wall

First operation with the JET International Thermonuclear Experimental Reactor-like wall

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