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| 2. |
- Airila, M. I., et al.
(author)
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ERO modelling of local deposition of injected C-13 tracer at the outer divertor of JET
- 2009
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In: Physica Scripta. - 0031-8949 .- 1402-4896. ; T138, s. 014021-
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Journal article (peer-reviewed)abstract
- The 2004 tracer experiment of JET with the injection of (CH4)-C-13 into H-mode plasma at the outer divertor has been modelled with the Monte Carlo impurity transport code ERO. EDGE2D solutions for inter-ELM and ELM-peak phases were used as plasma backgrounds. Local two-dimensional (2D) deposition patterns at the vertical outer divertor target plate were obtained for comparison with post-mortem surface analyses. ERO also provides emission profiles for comparison with radially resolved spectroscopic measurements. Modelling indicates that enhanced re-erosion of deposited carbon layers is essential in explaining the amount of local deposition. Assuming negligible effective sticking of hydrocarbons, the measured local deposition of 20-34% is reproduced if re-erosion of deposits is enhanced by a factor of 2.5-7 compared to graphite erosion. If deposits are treated like the substrate, the modelled deposition is 55%. Deposition measurements at the shadowed area around injectors can be well explained by assuming negligible re-erosion but similar sticking behaviour there as on plasma-wetted surfaces.
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| 3. |
- Allen, S. L., et al.
(author)
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C-13 transport studies in L-mode divertor plasmas on DIII-D
- 2005
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In: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 337-39:03-jan, s. 30-34
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Journal article (peer-reviewed)abstract
- (CH4)-C-13 was injected with a toroidally-symmetric gas system into 22 identical lower-single-null L-mode discharges on DIII-D. The injection level was adjusted so that it did not significantly perturb the core or divertor plasmas, with a duration of similar to 3 s on each shot, for a total of similar to 300 T L of injected particles. The plasma shape remained very constant; the divertor strike points were controlled to similar to 1 cm at the divertor plate. At the beginning of the subsequent machine vent, 29 carbon tiles were removed for nuclear reaction analysis of C-13 content to determine regions of carbon deposition. It was found that only the tiles inboard of the inner strike point had appreciable 1 3 C above background. Visible spectroscopy measurements of the carbon injection and comparisons with modeling are consistent with carbon transport by means of scrape-off layer flow.
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| 4. |
- Coad, J. P., et al.
(author)
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Distribution of hydrogen isotopes, carbon and beryllium on in-vessel surfaces in the various jet divertors
- 2005
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In: Fusion science and technology. - 1536-1055 .- 1943-7641. ; 48:1, s. 551-556
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Journal article (peer-reviewed)abstract
- JET has operated with divertors of differing geometries since 1994. Impurities accumulated in the inner leg of all the divertors, and operation of the first (Mk I) divertor with beryllium tiles demonstrated that most are eroded from the main chamber walls and swept along the scrape-off layer to the inner divertor. Carbon deposited at the inner divertor is then locally transported to shadowed regions such as the inner louvres, where, for example, most of the tritium was trapped during the deuterium-tritium experiment (DTE1). Factors affecting these transport processes (e.g. temperature) are important for ITER, but are not well understood.
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| 5. |
- Coad, J. P., et al.
(author)
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Erosion and deposition in the JET MkII-SRP divertor
- 2007
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In: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 363, s. 287-293
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Journal article (peer-reviewed)abstract
- Carbon-13 labelled methane was injected into the outer divertor during a series of H-mode discharges on the last day of operations with the JET MkII-SRP divertor. Tiles from around the vessel were removed during the subsequent shutdown and surface deposits were analysed by IBA techniques and SIMS. First attempts to model the pattern of 13 C deposition using EDGE2D are reported. Erosion of W markers at the outer divertor was observed, with implications for the ITER-like wall experiment planned for JET, whilst thin film growth in the same region has been followed by the effect on infrared measurements. The composition of thick films deposited at the inner divertor during the MkII-SRP campaign, and the migration to the inner corner of the divertor observed by a quartz micro-balance, provide further information on divertor transport. Crown
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| 6. |
- Krokowski, D, et al.
(author)
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Yeast ribosomal P0 protein has two separate binding sites for P1/P2 proteins
- 2006
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In: Molecular Microbiology. - : Wiley. - 1365-2958 .- 0950-382X. ; 60:2, s. 386-400
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Journal article (peer-reviewed)abstract
- The ribosome has a distinct lateral protuberance called the stalk; in eukaryotes it is formed by the acidic ribosomal P-proteins which are organized as a pentameric entity described as P0-(P1-P2)(2). Bilateral interactions between P0 and P1/P2 proteins have been studied extensively, however, the region on P0 responsible for the binding of P1/P2 proteins has not been precisely defined. Here we report a study which takes the current knowledge of the P0 - P1/P2 protein interaction beyond the recently published information. Using truncated forms of P0 protein and several in vitro and in vivo approaches, we have defined the region between positions 199 and 258 as the P0 protein fragment responsible for the binding of P1/P2 proteins in the yeast Saccharomyces cerevisiae. We show two short amino acid regions of P0 protein located at positions 199-230 and 231-258, to be responsible for independent binding of two dimers, P1A-P2B and P1B-P2A respectively. In addition, two elements, the sequence spanning amino acids 199-230 and the P1A-P2B dimer were found to be essential for stalk formation, indicating that this process is dependent on a balance between the P1A-P2B dimer and the P0 protein.
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| 7. |
- Pitts, R. A., et al.
(author)
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Material erosion and migration in tokamaks
- 2005
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In: Plasma Physics and Controlled Fusion. - 0741-3335 .- 1361-6587. ; 47, s. B303-B322
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Journal article (peer-reviewed)abstract
- The issue of first wall and divertor target lifetime represents one of the greatest challenges facing the successful demonstration of integrated tokamak burning plasma operation, even in the case of the planned next step device, ITER, which will run at a relatively low duty cycle in comparison to future fusion power plants. Material erosion by continuous or transient plasma ion and neutral impact, the susbsequent transport of the released impurities through and by the plasma and their deposition and/or eventual re-erosion constitute the process of migration. Its importance is now recognized by a concerted research effort throughout the international tokamak community, comprising a wide variety of devices with differing plasma configurations, sizes and plasmafacing component material. No single device, however, operates with the first wall material mix currently envisaged for ITER, and all are far from the ITER energy throughput and divertor particle fluxes and fluences. This paper aims to review the basic components of material erosion and migration in tokamaks, illustrating each by way of examples from current research and attempting to place them in the context of the next step device. Plans for testing an ITER-like first wall material mix on the JET tokamak will also be briefly outlined.
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| 8. |
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| 9. |
- Abramowicz, Marek A, 1945, et al.
(author)
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A note on the slope-shift anticorrelation in the neutron star kHz QPOs data
- 2005
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In: n Proceedings of RAGtime 6/7: Workshops on black holes and neutron stars. - 807248334X
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Conference paper (peer-reviewed)abstract
- Observations show that the upper νU and lower νL of the ``twin peak'' high frequency QPOs in neutron star sources vary along lines νU = AνL + B in a frequency-frequency plot, and that their ratios νU/νL cluster near the value 3/2. This behaviour is well consistent with the predictions of the non-linear resonance model for QPOs. In this Note, we further explore our recent finding that the coefficients A, B of the frequency-frequency lines for individual sources are anticorrelated. In the (A,B) plane, they occupy rather a narrow region along the line A = 3/2 - B/600 Hz. We show that this observational property of QPOs also follows from the resonance model
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| 10. |
- Abramowicz, Marek A, 1945, et al.
(author)
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Introduction
- 2008
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In: New Astronomy Reviews. - : Elsevier BV. - 1387-6473. ; 51
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Journal article (other academic/artistic)
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