Residual carbon content in the initial ITER-Like Wall experiments at JET

Brezinsek, S.; Jachmich, S.; Stamp, M.; Meigs, A.; Coenen, J. W.; Krieger, K.; Giroud, C.; Groth, M.; Philipps, V.; Grünhagen, S.; Smith, R.; Rooij, G.J. van; Ivanova, Darya; Matthews, G. F.

doi:10.1016/j.jnucmat.2013.01.122

Cited by 78 publications

(70 citation statements)

References 17 publications

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“…no impurities in the wall prior to plasma exposure. According to [20] this is a reasonable assumption for JET-ILW. For JET-C this amounts to shots long after the last Be evaporation, as the ones used for gas balance measurements in [14].…”

Section: Modeled Jet Shotsmentioning

confidence: 99%

“…For an overview of the JET-ILW limiter plasmas see [20]. The background plasma for the H-mode shot 83559 was also created using the OSM approach using inter ELM profiles of T e and N e at the targets and upstream at the outer mid-plane.…”

Section: Modeled Jet Shotsmentioning

confidence: 99%

“…The background plasma for the H-mode shot 83559 was also created using the OSM approach using inter ELM profiles of T e and N e at the targets and upstream at the outer mid-plane. The conditions for shot 83559 are also described in [20] For the JET-C cases a pure C wall and for JET-ILW a pure Be main wall was assumed as initial conditions i.e. no impurities in the wall prior to plasma exposure.…”

Section: Modeled Jet Shotsmentioning

confidence: 99%

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Quantitative modeling of fuel retention in the JET-C and JET-ILW wall configurations by WallDYN and predictions for ITER

Schmid

Krieger

Lisgo

et al. 2015

Journal of Nuclear Materials

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The fuel retention in ITER will be dominated by co-deposition. Therefore predictions of retention in ITER require a global model of migration of light (Be, C) impurities and their co-deposition with hydrogenic species. To track the global material erosion/deposition balance and the resulting formation of mixed material layers the WallDYN code has been developed. This paper describes the application of WallDYN to the interpretation of results on deposition and co-deposition in JET experiments both in the ITER like wall (ILW) and full carbon configuration. The calculations show qualitative agreement with the Be deposition patterns determined from post-campaign wall tile analysis. The calculated retention results for C and Be first wall configurations even show quantitative agreement with experimental gas balance measurements when long term outgassing is taken into account. Applying WallDYN to ITER for different first wall and plasma configurations shows that for the current (Be + W only) material choice, retention will not limit ITER operation whereas C would increase retention by factors 10 to 100, leading to unacceptably high fuel retention by co-deposition.

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Section: Modeled Jet Shotsmentioning

confidence: 99%

Section: Modeled Jet Shotsmentioning

confidence: 99%

Section: Modeled Jet Shotsmentioning

confidence: 99%

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Quantitative modeling of fuel retention in the JET-C and JET-ILW wall configurations by WallDYN and predictions for ITER

Schmid

Krieger

Lisgo

et al. 2015

Journal of Nuclear Materials

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“…Monitoring pulses were introduced to the routine plasma operations of JET-ILW [13] and typically performed once a week, in order to allow tracking the evolution of the machine performance and intrinsic impurities throughout the 2011/2012 campaigns. After the initial restart of JET-ILW about 300 JET Pulses (2000s) of divertor operation were required to establish a steady state divertor composition [14].…”

Section: Impurity Sources and Contentmentioning

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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“…W sputtering which determines the lifetime of the divertor components in the Be/W mix is dominated by intrinsic impurities such as Be, O and C, and extrinsic impurities like N 2 and Ar [2], though the C and Be content are orders of magnitude lower in quantity in comparison with the carbon wall [3]. As the JET-ILW does not include carbon-based PFCs, nitrogen is being seeded to replace carbon as the radiating species in the plasma edge and mitigate heat loads at the W target plates [4].…”

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confidence: 99%

Mass spectrometry analysis of the impurity content in N2 seeded discharges in JET-ILW

Drenik

Oberkofler

Alegre

et al. 2015

Journal of Nuclear Materials

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Presented are the results of the first mass spectrometry study of impurities at JET with the ILW. Measurements are performed with the newly-installed RGA system that allows for data acquisition in all stages of machine operation. Impurities are predominantly found in the 16 -20 AMU range, populated by water, methane and ammonia, and at 28 AMU (CO and N 2 ). The main contaminants in non-seeded discharges are deuterated methane and water, and nitrogen, which are present only in low amounts, and are likely produced by plasmasurface interaction. During N 2 seeded discharges, signals increase significantly at 28 AMU, but also in the 16 -20 AMU range, indicating conversion of nitrogen to ammonia. In subsequent non-seeded discharges, impurity content is reduced by an order of magnitude, however it exhibits a 5 -7 discharge-long legacy.

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Residual carbon content in the initial ITER-Like Wall experiments at JET

Cited by 78 publications

References 17 publications

Quantitative modeling of fuel retention in the JET-C and JET-ILW wall configurations by WallDYN and predictions for ITER

Quantitative modeling of fuel retention in the JET-C and JET-ILW wall configurations by WallDYN and predictions for ITER

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

Mass spectrometry analysis of the impurity content in N2 seeded discharges in JET-ILW

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