Modelling ELM heat flux deposition on the ITER main chamber wall

Kočan, M.; Pitts, R.A.; Lisgo, S.; Loarte, A.; Gunn, J.; Fuchs, V.

doi:10.1016/j.jnucmat.2014.11.130

Cited by 17 publications

(14 citation statements)

References 13 publications

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“…In recent modelling efforts, it was estimated that ELMs could cyclically cause surface temperatures of up to 700 °C on the beryllium armor [23]. Even though this temperature is significantly lower than the surface temperatures that coincided with the transition region formation in the present work (min.…”

Section: Grain Boundary Oxide Segregation and The Formation Of A Tran...contrasting

confidence: 49%

“…The tendency of the temperature threshold to drop for longer holding times during the transient heat loading could possibly proceed down to ~600 °C [21], which is already below estimated surface temperatures of ~700 °C during ELMy operation at certain locations of the ITER FW [23]. Therefore, it can be concluded that the observed oxide segregation at the Be grain boundaries is possible under ITER operational conditions and further experimental studies are suggested to determine the temperature/holding time thresholds.…”

Section: Discussionmentioning

confidence: 92%

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Oxide segregation and melting behavior of transient heat load exposed beryllium

et al. 2016

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In the experimental fusion reactor ITER, beryllium will be applied as first wall armor material. However, the ITER-like wall project at JET already experienced that the relatively low melting temperature of beryllium can easily be exceeded during plasma operation. Therefore, a detailed study was carried out on S-65 beryllium under various transient, ITER-relevant heat loads that were simulated in the electron beam facility JUDITH 1. Hereby, the absorbed power densities were in the range of 0.15–1.0 GW m−2 in combination with pulse durations of 1–10 ms and pulse numbers of 1–1000. In metallographic cross sections, the emergence of a transition region in a depth of ~70–120 µm was revealed. This transition region was characterized by a strong segregation of oxygen at the grain boundaries, determined with energy dispersive x-ray spectroscopy element mappings. The oxide segregation strongly depended on the maximum temperature reached at the end of the transient heat pulse in combination with the pulse duration. A threshold for this process was found at 936 °C for a pulse duration of 10 ms. Further transient heat pulses applied to specimens that had already formed this transition region resulted in the overheating and melting of the material. The latter occurred between the surface and the transition region and was associated with a strong decrease of the thermal conductivity due to the weakly bound grains across the transition region. Additionally, the transition region caused a partial separation of the melt layer from the bulk material, which could ultimately result in a full detachment of the solidified beryllium layers from the bulk armor. Furthermore, solidified beryllium filaments evolved in several locations of the loaded area and are related to the thermally induced crack formation. However, these filaments are not expected to account for an increase of the beryllium net erosion.

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Section: Grain Boundary Oxide Segregation and The Formation Of A Tran...contrasting

confidence: 49%

Section: Discussionmentioning

confidence: 92%

Oxide segregation and melting behavior of transient heat load exposed beryllium

et al. 2016

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“…Those field lines that leave the area without intersecting any FWP are assumed to result in exposure of the corresponding location on the FILD to the plasma. The plasma-wetted area of the FILD is exposed to the superimposed time-averaged edge localized mode (ELM) heat flux density, obtained from a fluid model of the filament parallel transport [9], and static inter-ELM heat flux adopted from [10]. Additional heat load of 0.35 MW/m 2 due to plasma radiation is applied uniformly over the FILD surface.…”

Section: Jinst 12 C12027mentioning

confidence: 99%

“…The estimates of ∆T above do not include the instantaneous temperature rise during individual Edge Localized Modes (ELMs), ∆T ELM . Because of the short ELM heat pulse duration [9], ∆T ELM is restricted to the immediate vicinity of the FILD surface ( 1 mm) and does not affect e.g. the scintillator temperature.…”

Section: Jinst 12 C12027mentioning

confidence: 99%

“…However, it can lead to a local melting of the FILD surface. In [9] the instantaneous ELM heat pulse envelopes were obtained for controlled ELM for the range of the OMP separatrix distances of 4-10 cm. The corresponding ∆T ELM , obtained from the semi-infinite approach assuming q surf = q , the parallel heat flux density, is compiled in table 2.…”

Section: Jinst 12 C12027mentioning

confidence: 99%

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The impact of the fast ion fluxes and thermal plasma loads on the design of the ITER fast ion loss detector

et al. 2017

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Thermal plasma loads to the ITER Fast Ion Loss Detector are studied for Q DT = 10 burning plasma equilibrium using the 3D field line tracing. The simulations are performed for a FILD insertion 9-13 cm past the port plasma facing surface, optimized for fast ion measurements, and include the worst-case perturbation of the plasma boundary and the error in the magnetic reconstruction. The FILD head is exposed to superimposed time-averaged ELM heat load, static inter-ELM heat flux and plasma radiation. The study includes the estimate of the instantaneous temperature rise due to individual 0.6 MJ controlled ELMs. The maximum time-averaged surface heat load is 12 MW/m 2 and will lead to increase of the FILD surface temperature well below the melting temperature of the materials considered here, for the FILD insertion time of 0.2 s. The worst-case instantaneous temperature rise during controlled 0.6 MJ ELMs is also significantly smaller than the melting temperature of e.g. Tungsten or Molybdenum, foreseen for the FILD housing. K: Detector design and construction technologies and materials; Plasma diagnosticsprobes 1Corresponding author.

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