Wall conditioning of JET with the ITER-Like Wall

Douai, D.; Brezinsek, S.; Esser, H.G.; Joffrin, E.; Keenan, T.K.; Knipe, S.; Kogut, D.; Lomas, P. J.; Marsen, S.; Nunes, I.; Philipps, V.; Pitts, R.A.; Shimada, M.; Vries, P. de; Contributors, Jet

doi:10.1016/j.jnucmat.2013.01.259

Cited by 29 publications

(35 citation statements)

References 7 publications

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“…After installation of the JET ITER-like Wall (JET-ILW) the vessel was baked to 325°C, glow discharge cleaning in deuterium was carried out for about 100 hours and the temperature reduced to 200°C for first plasma [12]. There had been considerable debate on the need to clean the JET vessel of residual carbon after the CFC tiles were removed but in the end it was considered too costly in time and probably not needed.…”

Section: Residual Impurity Levelsmentioning

confidence: 99%

Plasma operation with an all metal first-wall: Comparison of an ITER-like wall with a carbon wall in JET

Matthews

Contributors

2013

Journal of Nuclear Materials

159

110

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Section: Residual Impurity Levelsmentioning

confidence: 99%

Plasma operation with an all metal first-wall: Comparison of an ITER-like wall with a carbon wall in JET

Matthews

Contributors

2013

Journal of Nuclear Materials

159

110

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“…An experimental study of GDC uniformity on JET using D 2 -GDC has been performed in which different anodes are successively operated and an array of wall mounted Langmuir probes measures wall ion flux as a function of active anode number [3]. The anodes are located in Octants 2, 4, 6 and 8 of JET, whereas probes are installed in Octant 1 and 8 (see Fig.…”

Section: Gdc In Jetmentioning

confidence: 99%

“…For these reasons the model benchmark is extended to larger devices with toroidal geometry: the JET (tokamak) and RFX (Reversed Field Pinch) devices, which have published recently experimentally obtained wall current densities during glow plasmas [3,4]. The model geometry is listed in Section 2; comparison of the experiment with modelling is given in the Sections 3 and 4 of the present paper.…”

Section: Introductionmentioning

confidence: 99%

“…In order to assess glow discharge uniformity and wall coverage, thus conditioning efficiency of the system, a new 2D multi-fluid model has been developed (Hagelaar, 2012). In this work the model is compared with published experimental data on GDC wall ion fluxes in JET and RFX (Douai et al, 2013;Canton et al, 2013). The simulations of H 2 -GDC in ITER for the case of 1 or 2 anodes indicate a good level of homogeneity of plasma parameters in the negative glow and of the wall ion flux in the common pressure domain for GDC: 0.1-0.5 Pa.…”

mentioning

confidence: 95%

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Modelling the ITER glow discharge plasma

Kogut

Douai

Hagelaar

et al. 2015

Journal of Nuclear Materials

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“…After installation of the ITER-like Wall in JET, a conditioning cycle of pumping, baking and glow discharge conditioning was carried out. Already, the first breakdown was successful due to the beneficial effect of Be first wall material [23] and no overnight glow discharges and no Be evaporation were necessary throughout the whole campaign in contrast to the experience with carbon walls. The profound impact of the ILW on plasma breakdown was investigated in more detail [20].…”

Section: B Conditioning Breakdown and Current Ramp-upmentioning

confidence: 99%

Experiences With Tungsten Plasma Facing Components in ASDEX Upgrade and JET

Neu¹,

Brezinsek

Beurskens

et al. 2014

IEEE Trans. Plasma Sci.

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Abstract-ASDEX Upgrade (AUG) has been converted to all W plasma facing components (PFCs) in 2007 and JET has implemented the ITER like wall (ILW) project (2011) using the same PFC configuration as ITER during its active phase, namely Be in the main chamber and tungsten in the divertor. As a result of the all metal PFCs in both devices much less surface conditioning is needed to arrive at reproducible wall conditions. Specifically the Be PFCs of JET led to a very small low-Z content (reduction of C and O by at least a factor of 10), reducing the edge radiation in steady state operation as well as during disruptions. Both devices successfully employ massive gas injection to mitigate disruption forces and power loads to PFCs by radiating up to 100% of the available energy. Hydrogen retention is strongly reduced (AUG: factor 5, JET: factor 10) and the remaining retention is still dominated by co-deposition with residual C in AUG and intrinsic Be in JET. The very low edge and divertor radiation could be compensated by impurity seeding either by a single gas species (N2) (AUG and JET) or by combining N2 and Ar (AUG) injection for divertor and main chamber radiation, respectively. The W sputtering in the divertor increases when seeding small amounts of N2, but decreases for higher fluxes due to the plasma cooling provided by the nitrogen radiation. The tungsten content is controlled by the source as well as by its edge and central transport. It could be kept sufficiently small by using a minimum gas fuelling to reduce the W erosion and to diminish the W penetration. The control of the central W transport by central (wave) heating had been well established in AUG, however in both devices the W content is increased during ICRH operation most probably due to increased W sputtering caused by rectified sheaths. The H-Mode threshold is reduced by 20-30% in AUG and JET, but on average the confinement is lower in JET-ILW than with C PFCs. To date it is not yet clear, whether the reduced H-Mode confinement has to be attributed to the use of W PFCs, since such a clear trend as in JET was not found in AUG.

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Wall conditioning of JET with the ITER-Like Wall

Cited by 29 publications

References 7 publications

Plasma operation with an all metal first-wall: Comparison of an ITER-like wall with a carbon wall in JET

Plasma operation with an all metal first-wall: Comparison of an ITER-like wall with a carbon wall in JET

Modelling the ITER glow discharge plasma

Experiences With Tungsten Plasma Facing Components in ASDEX Upgrade and JET

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