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- Ongena, J., et al.
(författare)
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Recent progress on JET towards the ITER reference mode of operation at high density
- 2001
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Ingår i: Plasma Physics and Controlled Fusion. - 0741-3335 .- 1361-6587. ; 43, s. A11-A30
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Tidskriftsartikel (refereegranskat)abstract
- Recent progress towards obtaining high density and high confinement in JET as required for the ITER reference scenario at Q = 10 is summarized. Plasmas with simultaneous confinement H-98(y.2) = 1 and densities up to n/n(Gw) similar to 1 are now routinely obtained. This has been possible (i) by using plasmas at high (delta similar to 0.5) and medium (delta similar to 0.3-0.4) triangularity with sufficient heating power to maintain Type I ELMs, (ii) with impurity seeded plasmas at high (delta similar to 0.5) and low (delta less than or equal to 0.2) triangularity, (iii) with an optimized pellet injection sequence, maintaining the energy confinement and raising the density, and (iv) by carefully tuning the gas puff rate leading to plasmas with peaked density profiles and good confinement at long time scales. These high performance discharges exhibit Type I ELMs, with a new and more favourable behaviour observed at high densities, requiring further studies. Techniques for a possible mitigation of these ELMs are discussed, and first promising results are obtained with impurity seeding in discharges at high triangularity. Scaling studies using the new data of this year show a strong dependence of confinement on upper triangularity, density and proximity to the Greenwald limit. Observed MHD instabilities and methods to avoid these in high density and high confinement plasmas are discussed.
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| 6. |
- Coad, J. P., et al.
(författare)
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Erosion/deposition in JET during the period 1999-2001
- 2003
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Ingår i: Journal of Nuclear Materials. - 0022-3115 .- 1873-4820. ; 313, s. 419-423
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Tidskriftsartikel (refereegranskat)abstract
- Coated divertor and wall tiles exposed in JET for the 1999-2001 operations have been used to assess erosion/deposition. Deposited films of up to 90 mum thickness at the inner wall of the divertor tiles are, for the most part, enriched in beryllium and other metals, whilst carbon is probably chemically sputtered from these tiles and transported to shadowed regions of the inner divertor. However, from the composition at the surface of the tiles, it appears that the chemical erosion was 'switched off' by reducing the JET vessel wall temperature for the last part of the operations to 200 degreesC. Thick powdery deposits localised at the ion transport limit at each corner of the divertor may be due to physical sputtering. Erosion of the coatings is seen at the outer divertor wall, and on all the inner wall and outer limiter tiles.
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| 7. |
- Lee, T W R, et al.
(författare)
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Precursor of human adenovirus core polypeptide Mu targets the nucleolus and modulates the expression of E2 proteins
- 2004
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Ingår i: Journal of General Virology. - : Microbiology Society. - 0022-1317 .- 1465-2099. ; 85:Pt 1, s. 185-196
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Tidskriftsartikel (refereegranskat)abstract
- We have examined the subcellular localization properties of human adenovirus 2 (HAdV-2) preMu and mature Mu (pX) proteins as fusions with enhanced green fluorescence protein (EGFP). We determined that preMu is exclusively a nucleolar protein with a single nucleolar accumulation signal within the Mu sequence. In addition, we noted that both preMu-EGFP and Mu-EGFP are excluded from adenovirus DNA-binding protein (DBP)-rich replication centres in adenovirus-infected cells. Surprisingly, we observed that cells in which preMu-EGFP (but not Mu-EGFP) is transiently expressed prior to or shortly after infection with Ad2 did not express late adenovirus genes. Further investigation suggested this might be due to a failure to express pre-terminal protein (preTP) from the E2 region, despite expression of another E2 protein, DBP. Deletion mutagenesis identified a highly conserved region in the C terminus of preMu responsible for these observations. Thus our data suggest that preMu may play a role in modulating accumulation of proteins from the E2 region.
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| 8. |
- Rubel, Marek J., et al.
(författare)
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Beryllium and carbon films in JET following D-T operation
- 2003
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Ingår i: Journal of Nuclear Materials. - 0022-3115 .- 1873-4820. ; 313, s. 321-326
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Tidskriftsartikel (refereegranskat)abstract
- After the D-T operation (DTE-1 campaign) at JET a large number of limiter and divertor tiles were dismounted from the torus for ex situ examination. The relative distributions of deuterium, tritium, beryllium and carbon are presented and discussed. Significant asymmetry observed in the distribution of erosion and deposition zones indicates preferential flow of the deuterium background plasma and impurities towards the inner divertor leg. The comparison of the beryllium content on the limiter tiles from the main chamber and the content of this element on the inner divertor tiles clearly proves the beryllium erosion from the main chamber wall and its transport to the divertor. However, no beryllium is detected in the shadowed regions of the divertor where the formation of thick and fuel-rich carbon films occurs. This is interpreted in terms of different mechanisms governing the erosion and transport of Be and C. The results allow a conclusion that the operation with a full beryllium wall would lead to a significantly decreased fuel inventory due to removal of the carbon source.
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| 9. |
- Rubel, Marek, et al.
(författare)
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Overview of tracer techniques in studies of material erosion re-depostion and fuel inventory in tokamaks
- 2004
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Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 329, s. 795-799
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Tidskriftsartikel (refereegranskat)abstract
- C-13 labeled methane and rhenium-boron coated plates were used at the JET tokamak as tracers for studies of the material transport, its erosion and re-deposition. Experimental procedures are described. The results are discussed in terms of processes underlying the material transport and the change of morphology of targets exposed to the plasma: physical sputtering, chemical erosion, prompt re-deposition. The influence of wall materials on fuel inventory is also addressed. C-14 measurements in the TEXTOR tokamak are presented and possibilities of using C-14 in carbon migration studies are considered.
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