Search

Your search keyword '"J. P. Coad"' showing total 15 results
Start Over Author "J. P. Coad" Topic plasma
15 results on '"J. P. Coad"'

1. Microstructure and inhomogeneous fuel trapping at divertor surfaces in the JET tokamak

Author

Per Petersson, Henric Bergsåker, Seppo Koivuranta, G. Possnert, Igor Bykov, J. P. Coad, Anna Widdowson, and J. Likonen

Subjects
deuterium retention, fusion, Nuclear and High Energy Physics, Jet (fluid), Ion beam analysis, Materials science, Tokamak, Divertor, microstructure, microbeam, Microbeam, Plasma, Microstructure, law.invention, Optical microscope, law, Deposited layers, Atomic physics, Instrumentation
Abstract

The plasma deposited layers at divertor surfaces in the JET tokamak with carbon wall have been studied post mortem, using micro ion beam analysis (µ-IBA) methods, optical microscopy and scanning electron microscopy (SEM). The layers were formed during plasma operations over different periods through 1998-2009. They frequently have a columnar structure. For µ-IBA a 3 MeV 3He beam was used, focused to about 5-15 µm size. Nuclear reaction analysis was used to measure D, Be and C. Elemental mapping was carried out both at the original surface and on polished layer cross sections. Trapped deuterium is predominantly found in remote areas on the horizontal bottom divertor tiles and in regions with locally enhanced deuterium concentration on the vertical tiles. Pockets with enhanced deuterium concentration are found in the carbon fibre composite (CFC) substrate. Areas with dimensions of about 100 µm with enhanced deuterium concentration are also found inside the deposited layers. The inhomogeneous fuel trapping is tentatively explained with co-deposition in partly protected pits in the substrate and by incorporation of dust particles in the growing layers

Published
2014
Full Text
View/download PDF

2. Material erosion and migration in tokamaks

Author

G. Federici, J. Strachan, R.A. Pitts, Marek Rubel, Jari Likonen, D. P. Coster, G. F. Matthews, Jet-Efda Contributors, K. Krieger, Wojciech Fundamenski, A. Kukushkin, J. P. Coad, and J. Horacek

Subjects
Tokamak, Nuclear engineering, fusion reactors, Context (language use), law.invention, Nuclear physics, law, ITER, divertor, divertor tiles, tokamak, plasma, Divertor, Magnetic confinement fusion, Plasma, Fusion power, first wall, Condensed Matter Physics, fusion energy, Nuclear Energy and Engineering, JET, Duty cycle, Environmental science, Transient (oscillation), divertor material, plasma-wall interactions
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 plasma-facing 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.

Published
2005
Full Text
View/download PDF

3. Hydrocarbon transport in the MkIIa divertor of JET

Author

A Kirschner, J N Brooks, V Philipps, J P Coad, and contributors to the EFDA-JET Workprogramme

Subjects
chemistry.chemical_classification, Jet (fluid), Materials science, Divertor, chemistry.chemical_element, Magnetic confinement fusion, Mechanics, Plasma, Condensed Matter Physics, Hydrocarbon, Nuclear Energy and Engineering, chemistry, Ionization, Erosion, ddc:530, Atomic physics, Carbon
Abstract

This contribution presents two-dimensional Monte-Carlo simulations of the local transport of hydrocarbons that are chemically eroded in the JET MkIIa divertor. The effect of a given background carbon flux flowing from the main plasma down to the divertor is also taken into account. The influence of local plasma temperatures and densities and the influence of different assumptions for the sticking of re-deposited particles hitting the tiles is analysed. Even under the assumption that the sticking of re-deposited hydrocarbon fragments is zero, a large amount (about 75%) of the eroded particles is re-deposited in the form of ionized carbon on the tiles. A reasonable agreement between the simulation and the experimental observation of the carbon deposition at the inner louvers in the MkIIa JET divertor is achieved, if high chemical erosion yields of about 20% together with a negligible effective sticking of hydrocarbons are assumed. Although there are experimental observations indicating such high erosion yields, such yields cannot be applied as a stationary value for the effective erosion since it would turn the inner divertor into a net erosion area in contrast to the experimental findings. The possibility of applying different erosion rates for (re)-deposited layers and the substrate material is discussed. To further improve the modelling a better knowledge about the formation and erosion of re-deposited layers is required. A first conclusion concerning the erosion and re-deposition behaviour in ITER will be drawn.

Published
2003
Full Text
View/download PDF

4. Plasma-material interactions in current tokamaks and their implications for next step fusion reactors

Author

W R Wampler, V. Philipps, Dennis Whyte, A.A. Haasz, C. Grisolia, Ahmed Hassanein, C. H. Skinner, J. Roth, Jeffrey N. Brooks, J. P. Coad, G. Federici, and C. S. Pitcher

Subjects
Nuclear and High Energy Physics, Thermonuclear fusion, Tokamak, Nuclear engineering, Scale (chemistry), Plasma energy, Plasma, Fusion power, Condensed Matter Physics, law.invention, Nuclear physics, law, Environmental science, Current (fluid), Engineering design process
Abstract

The major increase in discharge duration and plasma energy in a next step DT fusion reactor will give rise to important plasma-material effects that will critically influence its operation, safety and performance. Erosion will increase to a scale of several centimetres from being barely measurable at a micron scale in today's tokamaks. Tritium co-deposited with carbon will strongly affect the operation of machines with carbon plasma facing components. Controlling plasma-wall interactions is critical to achieving high performance in present day tokamaks, and this is likely to continue to be the case in the approach to practical fusion reactors. Recognition of the important consequences of these phenomena stimulated an internationally co-ordinated effort in the field of plasma-surface interactions supporting the Engineering Design Activities of the International Thermonuclear Experimental Reactor project (ITER), and significant progress has been made in better understanding these issues. The paper reviews the underlying physical processes and the existing experimental database of plasma-material interactions both in tokamaks and laboratory simulation facilities for conditions of direct relevance to next step fusion reactors. Two main topical groups of interaction are considered: (i) erosion/redeposition from plasma sputtering and disruptions, including dust and flake generation and (ii) tritium retention and removal. The use of modelling tools to interpret the experimental results and make projections for conditions expected in future devices is explained. Outstanding technical issues and specific recommendations on potential R&D avenues for their resolution are presented.

Published
2001
Full Text
View/download PDF

5. Similarities in divertor erosion/redeposition and deuterium retention patterns between the tokamaks ASDEX Upgrade, DIII-D and JET

Author

J. P. Coad, Dennis Whyte, P. Franzen, and H. Maier

Subjects
Nuclear and High Energy Physics, Jet (fluid), Materials science, Tokamak, DIII-D, Divertor, Plasma, Condensed Matter Physics, law.invention, Nuclear physics, Deuterium, ASDEX Upgrade, law, Erosion
Abstract

The similar poloidal patterns of divertor erosion and redeposition of the ASDEX Upgrade, DIII-D and JET tokamaks are examined by comparing hydrogen isotope retention at the surfaces of divertor tiles. The outer divertor strike point undergoes net erosion. The inner divertor is a region of net redeposition, with deuterium co-deposition rates ~20 μg m2 s-1 for all three devices; despite their differences in geometry, size and plasma facing materials. This extrapolates to an unacceptably high tritium retention rate in a DT burning steady state tokamak.

Published
1999
Full Text
View/download PDF

6. Global migration of impurities in tokamaks

Author

J. Likonen, V. Rohde, Jet-Efda Contributors, Marek Rubel, Markus Airila, H. W. Müller, C. Björkas, T. Makkonen, Anna Widdowson, R. Neu, A. Kirschner, A. Järvinen, T. Kurki-Suonio, Antti Hakola, D. Borodin, M. Mayer, J. P. Coad, S. Brezinsek, J. Miettunen, M. Groth, Seppo Koivuranta, P. Petersson, K. Krieger, and V. Lindholm

Subjects
Nuclear physics, Physics, Light nucleus, Jet (fluid), Tokamak, Nuclear Energy and Engineering, ASDEX Upgrade, law, Impurity, Plasma, Global migration, Condensed Matter Physics, law.invention
Abstract

The migration of impurities in tokamaks has been studied with the help of tracer-injection (13C and 15N) experiments in JET and ASDEX Upgrade since 2001. We have identified a common pattern for the migrating particles: scrape-off layer flows drive impurities from the low-field side towards the high-field side of the vessel. Migration is also sensitive to the density and magnetic configuration of the plasma, and strong local variations in the resulting deposition patterns require 3D treatment of the migration process. Moreover, re-erosion of the deposited particles has to be taken into account to properly describe the migration process during steady-state operation of the tokamak.

Published
2013
Full Text
View/download PDF

7. Review of neutral beam heating on JET for physics experiments and the production of high fusion performance plasmas

Author

R. König, N. Peacock, E. Martin, L. Lauro-Taroni, D.V. Bartlett, B. Ingram, G. Vlases, A. Sibley, C. Terella, C. Lowry, N. A. Gottardi, T. Elevant, G. Saibene, J. Christiansen, M. Baronian, A. Tesini, T. Raimondi, A. J. Bickley, J. How, H. van der Beken, A. Haigh, N. C. Hawkes, M. C. Ramos de Andrade, H. Morsi, G. Murphy, M. Botman, A. Dines, A. Gondhalekar, C. Gormezano, M. Irving, H. Brelen, M. Tabellini, B. Schunke, B.J.D. Tubbing, G. Sadler, P. R. Thomas, C. Gowers, P. E. Stott, G. Corrigan, S. Cooper, W. J. Brewerton, H. D. Falter, M. Keilhacker, A. Korotkov, V. Marchese, M. Cox, P. Breger, M. Nilsen, T. Szabo, M. L. Watkins, R. Claesen, C. J. Hancock, I. D. Young, S. Ali-Arshad, M. J. Watson, O. N. Jarvis, E. Bertolini, C. Walker, S. Clement, Y. Baranov, W. Bailey, G. Celentano, C. Froger, K. D. Lawson, D. Stork, D.F.H. Start, A. Cherubini, R. Monk, S. L. Dmitrenko, H. Jaeckel, S. Richards, C. A. Steed, L. G. Eriksson, S. F. Mills, S. J. Booth, P. G. Doyle, P. Meriguet, R. J. M. Pearce, H. Duquenoy, G. Radford, R. Prentice, F. Jensen, M. A. Pick, C. D. Challis, B. Alper, R. Wolf, J. Lingertat, F. Soldner, M. O'Mullane, N. Deliyanakis, P. Nielsen, A. C. Bell, R. Lasser, E. Deksnis, J. P. Coad, P. J. Harbour, E. M. Jones, T. Budo, F. Marcus, N. Davies, B. Balet, F.G. Rimini, M. Comiskey, T. Wade, P. Burton, T. Bonicelli, P. Gaze, K. Fullard, D. Martin, W. Zwingmann, T. Winkel, M. Ottaviani, P. Massmann, J. O'Rourke, D. Bond, P. Boucquey, P. Barabaschi, R. D. Gill, M. Cooke, B. Patel, W. Suverkroop, A. Kaye, D. Chiron, T. Businaro, D. Goodall, M.F. Stamp, G. B. Denne-Hinnov, R. Ostrom, A. Girard, L. Horton, F. Trevalion, C. Woodward, J. Ehrenberg, M. Johnson, A. Loarte, S. Puppin, R. Simoni, J. Jacquinot, A. Galetsas, W. Obert, M. Schmid, J. F. Junger, J. F. Jaeger, P. Andrew, L. Rossi, K. Borras, P. Smeulders, R. Reichle, A. Rolfe, J. Plancoulaine, P. Chuilon, T. T. C. Jones, R. Barnsley, A. Gibson, P. Card, N. Dolgetta, R. Rookes, M. Rapisarda, A. Colton, P. Schild, H. Buttgereit, M. von Hellermann, C. Perry, Henrik Bindslev, M. Garribba, F. Hurd, J. Mart, C. Sborchia, S. M. Scott, K. Blackler, A. Santagiustina, G. Bosia, C. Cottrell, I. Coffey, G. Newbert, S. Papastergiou, P. Butcher, L. Svensson, G. Vayakis, O. Da Costa, T. Hender, S. Weber, C. F. Maggi, V. V. Parail, P. Froissard, A. Taroni, A.E. Costley, J. P. Poffe, V.P. Bhatnagar, A. C. Maas, Y. Agarici, K. Thomsen, H. McBryan, Francesco Porcelli, H. Altmann, T. J. Wijnands, T. Brown, R. T. Ross, D. O'Brien, R. N. Litunovski, J. J. Davies, R. Russ, P. Kupschus, Annika Ekedahl, G. Magyar, G. Fishpool, H. Deesch, A. C. C. Sips, N. G. Kidd, C. Caldwell-Nichols, T. P. Hughes, M. Newmann, R. Sartori, S. Corti, S. K. Erents, T. Martin, R. Haange, A. M. Edwards, J.A. Dobbing, M. Gadeberg, G. Matthews, Laurie Porte, M. Wykes, D. Wilson, S. J. Davies, J. M. Adams, D. Ward, Wolfgang Kerner, L. Zannelli, J. G. Cordey, A. Tanga, P. Peacock, P. Bertoldi, H. Summers, L. Galbiati, W. J. Dickson, N. P. Hawkes, Michael Loughlin, David Campbell, D. Summers, P. Stangeby, D. Campling, J. L. Hemmerich, G. Benali, S. E. Dorling, J.A. Hoekzema, P. Haynes, J. L. Salanave, F. Junique, M. Salisbury, M. Brusati, J. Wesson, E. Oord, R. Giannella, M. Bures, J. Freiling, G. Janeschitz, M. Huart, E. Righi, G. Sanazzaro, P. J. Lomas, G. Deschamps, P. Stubberfield, M. Lennholm, E. Thompson, B. Macklin, P. J. Howarth, L. P. D. F. Jones, B. E. Keen, P. Noll, M. Brandon, R. Smith, P. Barker, F. Nave, P.D. Morgan, and P. Crawley

Subjects
Physics, Fusion, Jet (fluid), Mechanical Engineering, Nuclear engineering, Plasma, Neutral beam injection, Ion, Nuclear physics, Nuclear Energy and Engineering, Nuclear fusion, General Materials Science, Tritium, Beam (structure), Civil and Structural Engineering
Abstract

The JET neutral beam injection system has proved to be both effective and reliable as a plasma heating device. The ion heating and plasma fuelling characteristics of the system are ideally suited to the production of high fusion performance plasmas while the flexibility in the choice of beam species (H, D, T, 3 He or 4 He) and the ability to inject into almost any JET plasma configuration allows a wide variety of related physics experiments to be carried out. The capability to inject (for the first time) tritium beams was essential to the successful execution of the first tritium experiments in which 1.7 MW of power from DT fusion reactions was generated.

Published
1995
Full Text
View/download PDF

8. Overview of high performance H-modes in JET

Author

A. C. C. Sips, A.E. Costley, F. Hurd, G. Saibene, M. Salisbury, M. Brusati, C. Perry, P. J. Harbour, T. Martin, J. P. Poffe, Laurie Porte, H. van der Beken, N. C. Hawkes, J. Wesson, M. Bures, G. Janeschitz, M. Huart, A. Santagiustina, G. Bosia, H. Altmann, J. L. Salanave, A. Dines, N. G. Kidd, F. Junique, E. Righi, P. J. Lomas, P. G. Doyle, J. G. Cordey, G. Magyar, V. V. Parail, K. Thomsen, A. Gondhalekar, M. Irving, C. Gowers, R. Ostrom, C. Woodward, A. Galetsas, A. Loarte, P. Card, P. Trevalion, A. M. Edwards, T. P. Hughes, F. Jensen, M. Newman, C. Caldwell-Nichols, N. Peacock, P. Smeulders, A. Korotkov, A. Colton, P. Chuilon, T. T. C. Jones, F.G. Rimini, T. Winkel, P. Stubberfield, M. A. Pick, J.A. Hoekzema, T. Szabo, J. M. Adams, R. Prentice, Wolfgang Kerner, L. Zannelli, M. Rapisarda, D.F.H. Start, L. G. Eriksson, P. Schild, M. Wykes, D. Wilson, S. J. Davies, A. Sibley, P. Haynes, B. Alper, R. Wolf, T. Elevant, R. T. Ross, J. O'Rourke, E. Thompson, C. J. Hancock, R. Haange, P. E. Stott, A. Tesini, B. Macklin, M. Baronian, W. J. Brewerton, M.F. Stamp, L. P. D. F. Jones, A. C. Maas, B. E. Keen, A. Taroni, H. Morsi, G. Murphy, H. D. Falter, M. Keilhacker, I. D. Young, M. von Hellermann, A. Girard, A. Haigh, M. Cooke, A. Cherubini, Henrik Bindslev, D. Goodall, L. Horton, S. K. Erents, J.A. Dobbing, M. Gadeberg, E. Deksnis, G. Matthews, M. Comiskey, T. Wade, F. Marcus, M. Schmid, P. Burton, M. Garribba, G. Newbert, P. Barabaschi, A. Peacock, V. Marchese, C. Froger, K. D. Lawson, P. Noll, M. Brandon, G. Sadler, P. R. Thomas, C. F. Maggi, W. Bailey, D. Ward, K. Blackler, A. Rolfe, T. J. Wijnands, R. Barnsley, G. Celentano, R. Russ, Annika Ekedahl, G. Vayakis, T. Bonicelli, P. Froissard, C. Walker, J. Jacquinot, J. Plancoulaine, P. Kupschus, N. Dolgetta, Y. Agarici, D. Summers, M. Ottaviani, H. Brelen, S. Ali-Arshad, C. Sborchia, R. Claesen, C. A. Steed, S. F. Mills, A. Gibson, R. Smith, B. Schunke, B.J.D. Tubbing, J. Mart, H. McBryan, L. Svensson, J. J. Davis, S. M. Scott, R. J. M. Pearce, J. P. Coad, F. Soldner, T. Budd, P. Stangeby, E. M. Jones, V.P. Bhatnagar, C. D. Challis, R. Rookes, D. Campling, I. Coffey, W. Zwingmann, A. C. Bell, E. Oord, D. O'Brien, P. Gaze, N. Davies, D. Bond, David Campbell, P. Barker, F. Nave, G. B. Denne-Hinnov, S. Papastergiou, R. Monk, S. L. Dmitrenko, B. Balet, P. Butcher, L. Rossi, K. Borras, O. Da Costa, R. Giannella, P. Massmann, R. D. Gill, R. Sartori, J. Lingertat, S. Weber, R. N. Litunovski, H. Buttgereit, J. Ehrenberg, B. Patel, R. Lasser, N. A. Gottardi, A. Kaye, T. Brown, J. Christiansen, T. Businaro, L. Lauro-Taroni, C. Gormezano, O. N. Jarvis, S. Clement, A. J. Bickley, J. Freiling, D.V. Bartlett, D. Chiron, M. Botman, B. Ingram, C. Terella, C. Lowry, W. Obert, M. Tabellini, S. Corti, S. Cooper, P. Bertoldi, E. Bertolini, H. Summers, P.D. Morgan, P. Crawley, R. Reichle, Francesco Porcelli, G. Sanazzaro, G. Corrigan, T. Raimondi, G. Deschamps, M. J. Watson, M. C. Ramos de Andrade, G. Fishpool, H. Deesch, J. L. Hemmerich, G. Benali, Y. Baranov, H. Jaeckel, S. E. Dorling, G. Radford, S. J. Booth, J. F. Junger, H. Duquenoy, M. Lennholm, L. Galbiati, W. J. Dickson, N. P. Hawkes, R. Simonini, Michael Loughlin, T. Hender, M. Cox, P. Breger, W. Suverkropp, M. Nilsen, M. L. Watkins, S. Puppin, D. Stork, S. Richards, P. Nielsen, P. Boucquey, G.A. Cottrell, A. Tanga, P. J. Howarth, K. Fullard, D. Martin, M. Johnson, J. F. Jaeger, P. Andrew, P. Meriguet, Ralf König, M. O'Mullane, N. Deliyanakis, E. Martin, G. Vlases, and J. How

Subjects
Physics, Nuclear Energy and Engineering, Diamagnetism, Plasma, Atomic physics, Condensed Matter Physics, Phenomenology (particle physics), Scaling, Ion
Abstract

An account is given of the high performance plasmas established by development of the H-mode regime in JET in the experimental campaigns up to 1992. High performance in this case is measured in terms of the confinement enhancement achieved over the L-mode scaling as measured using the plasma diamagnetism. Three JET H-mode regimes have achieved enhancement factors (H G DIA ) over Goldston L-mode scaling of 2.5 < H G DIA < 4.0. These are the Pellet Enhanced Performance (PEP) H-MODE, the high bootstrap fraction (high β POL ) H-mode and the Hot Ion (HI) H-mode. The phenomenology of these three regimes is reviewed and contrasts and common threads are elucidated

Published
1994
Full Text
View/download PDF

9. Plasma radiation distribution and radiation loads onto the vessel during transient events in JET

Author

Jet-Efda Contributors, R.A. Pitts, Gennady Sergienko, S. Brezinsek, W. Fundamenski, V. Philipps, A. Huber, Julia Fuchs, P. Andrew, K. McCormick, A. Loarte, Ph. Mertens, T. Eich, Juergen Rapp, S. Jachmich, J. P. Coad, G. F. Matthews, M. F. Stamp, and JET EFDA Contributors

Subjects
Nuclear and High Energy Physics, Jet (fluid), Chemistry, Divertor, Bolometer, Plasma, Radiation, Fusion power, Radiation pattern, law.invention, Nuclear physics, Nuclear Energy and Engineering, law, Radiative transfer, General Materials Science, Atomic physics
Abstract

The JET bolometer camera system allows greatly improved tomographic reconstruction of the radiation pattern on a timescale of the order of the typical duration of a Type I ELM period (approximate to 0.1-0.4 ms). The ELM-induced radiation is always higher at the inner than at the outer divertor with an approximately linear increase of the asymmetry up to a total Delta W-ELM of about 0.6 MJ and a decrease for higher Delta W-ELM. Large Type I ELMs with energy losses above 0.65-0.7 MJ show enhanced radiation losses, which are associated with the ablation of thick co-deposited layers in the inner divertor. During the 'compound' phase, plasma contamination can increase but does not usually lead to radiative collapse of the plasma. It is found that the radiation distribution during the transient events is poloidally asymmetric with a maximum of the observed 'radiation peaking factor' for the disruptive current quench and for MARFEs of about 4.5, and less than 5 during VDEs. (C) 2009 Elsevier B.V. All rights reserved.

Published
2009

10. Tungsten erosion in the outer divertor of JET

Author

H. Maier, M. Balden, J. P. Coad, Jet-Efda Contributors, Stefan Lindig, V. Philipps, M. Mayer, J. Likonen, E. Vainonen-Ahlgren, and JET-EFDA Contributors

Subjects
Nuclear and High Energy Physics, Jet (fluid), Materials science, tungsten, Divertor, chemistry.chemical_element, Fusion power, Tungsten, equipment and supplies, erosion, Nuclear physics, fusion energy, Nuclear Energy and Engineering, chemistry, ASDEX Upgrade, ASDEX upgrade, JET, ITER, Erosion, divertor, General Materials Science, Composite material, Carbon, Deposition (law), plasma
Abstract

Erosion of tungsten in the outer JET divertor was determined with a set of tungsten coated divertor tiles during the 2001–2004 discharge campaign. The tungsten marker was strongly eroded, with the largest erosion at the outer strike point position, where more than 75% of the initial W disappeared. Strong erosion is also observed at the outer baffle and horizontal apron of tile 8, where about half of the tungsten has been removed. These numbers are lower boundaries, because the W was locally completely eroded. The tungsten erosion is inhomogeneous on a microscopic level and depends on the micro-topography of the rough surface: large erosion with complete disappearance of the W layer is observed on plasma-facing areas of microscopic ridges, while a smaller erosion and sometimes even deposition of carbon is found on the far side of ridges and in pores.

Published
2007
Full Text
View/download PDF

11. Tungsten coating on JET divertor tiles for erosion/deposition studies

Author

J. P. Coad, D.E. Hole, Jari Likonen, M. Mayer, Sari Lehto, Jukka Kolehmainen, Tommy Ahlgren, and H. Maier

Subjects
Materials science, tungsten, Joint European Torus, fusion reactors, chemistry.chemical_element, Temperature cycling, Tungsten, deposition, Sputtering, ITER, divertor, General Materials Science, divertor tiles, Composite material, plasma, Civil and Structural Engineering, Power density, Jet (fluid), Mechanical Engineering, Divertor, erosion, fusion energy, Nuclear Energy and Engineering, chemistry, JET, Deposition (chemistry), tungsten coating
Abstract

Six Joint European Torus (JET) divertor tiles were coated with tungsten marker stripes for erosion/deposition studies. The average thickness was 3.4 μm and the film was uniform within 5% across and within 10% along the stripe. Small amounts of impurities C, Fe, Ni and Cr were found and the in-plane stress was 965 MPa. Resistance to high heat loads was tested in the Neutral Beam Test-bed at JET where a coated carbon fibre composite block was exposed to a total of 113 pulses with a maximum peak power density of 15.7 MW m −2 and a maximum surface temperature of 1280 °C. No visible changes as a result of thermal cycling nor sputtering of the film by deuterium could be detected.

Published
2003
Full Text
View/download PDF

12. First results with the modified JET

Author

S. Clement, P. Nielsen, D. V. Bartlett, R. Goulding, M. Bures, P. Boucquey, R. Claesen, M. Cox, P. Breger, W. Suverkropp, M. L. Watkins, S. Richards, C. J. Hancock, I. D. Young, P. Card, T. Raimondi, H. Jaeckl, R. Ostrom, J. Mart, Henrik Bindslev, E. van der Goot, C. Woodward, D. Summers, R. König, B. Schunke, T. Hender, E. Thompson, F. Sartori, F. Cecil, P. Chuilon, T. T. C. Jones, S. Milani, G. Saibene, R. Prentice, B. Macklin, L. Svensson, J. Lingertat, P. Smeulders, R. L. Shaw, N. Watkins, R. J. M. Pearce, H. van der Beken, N. C. Hawkes, J. Jacquinot, P. Stubberfield, N. G. Kidd, T. P. Hughes, T. Elevant, R. Monk, W. Zwingmann, J.A. Hoekzema, S. Papastergiou, G. Vlases, R. Lasser, B. Fischer, S. L. Dmitrenko, C. D. Challis, L. Lauro-Taroni, F. Hurd, R. T. Ross, R. Cusack, D. Wilson, H. Brelen, David Campbell, A. C. Maas, G. Cottrell, E. Bertolini, J. How, J. Plancoulaine, R. Russ, O. Da Costa, K. Lawson, J. P. Poffe, N. Peacock, L. Porte, L. Galbiati, S. Ali-Arshad, B. Ingram, B. Alper, R. Wolf, K. Fullard, E. Oord, H. Altmann, A. M. Edwards, C. Terella, C. Lowry, D. Martin, E. Deksnis, A. Rossi, D. O'Brien, S. J. Davies, J. J. Davis, F. Marcus, R. Giannella, C. Walker, V. Bhatnagar, C. A. Steed, A. Gibson, F. Jensen, A. Ekedahl, M. Baronian, J. M. Adams, M. A. Pick, E. M. Jones, N. P. Hawkes, G. D'Antona, P. Schild, L. Horton, J. Freiling, D. Bond, G. Sadler, Wolfgang Kerner, D. Stork, N. Davies, S. K. Erents, R. Simonini, Michael Loughlin, M. Stamp, M. Schmid, P. J. Harbour, L. Zannelli, M. Schaffer, R. D. Gill, F. Nguyen, M. Gadeberg, A. Tanga, A. Haigh, B. Balet, F. Junique, G. Matthews, M. Johnson, G. Sanazzaro, P. R. Thomas, T. Budd, J. L. Hemmerich, G. Benali, A. Peacock, S. E. Dorling, G. McCormick, J. Dobbing, J. F. Jaeger, P. Andrew, P. Froissard, C. Perry, A. Santagiustina, M. von Hellermann, W. Bailey, D. Ward, C. Caldwell-Nichols, B. Patel, G. Celentano, T. Wade, V. V. Parail, T. Businaro, E. Lazzaro, A. C. Bell, G. Vayakis, G. Fishpool, H. Deesch, F. Rimini, S. Colombi, S. Puppin, B. Tubbing, W. Obert, A. C. C. Sips, F. Soldner, J. Christiansen, A. Sibley, N. Zornig, A. Rookes, M. Salisbury, A. Kaye, D. Chiron, N. A. Gottardi, J. Wesson, S. Sharapov, T. Martin, S. Weber, P. Lomas, D. Campling, P. Lamalle, A. Rolfe, M. Cooke, D. Goodall, A. J. Bickley, N. Deliyanakis, P. Morgan, A. Tesini, B. Fechner, I. Hutchinson, M. Garribba, R. Reichle, F. Porcelli, R. Barnsley, G. Newbert, G. Murphy, M. Tabellini, P. Stangeby, M. Huart, S. Cooper, E. Righi, L. Rossi, K. Borras, L. G. Eriksson, C. F. Maggi, C. Froger, J. G. Cordey, N. Dolgetta, H. Buttgereit, O. Pogutse, Y. Agarici, S. M. Scott, S. Ishida, D. F. Start, P. E. Stott, A. Meigs, W. J. Brewerton, H. D. Falter, M. Keilhacker, J. P. Coad, V. Marchese, A. Dines, A. Gondhalekar, M. Irving, C. Gowers, H. Guo, K. Thomsen, C. Laviron, C. Gormezano, A. Taroni, A. Howman, P. Kupschus, T. Szabo, M. Ottaviani, P. Burton, P. Ageladarakis, O. N. Jarvis, J. Ehrenberg, P. Savrukhin, T. Bonicelli, M. J. Watson, Y. Baranov, H. Duquenoy, T. Brown, Ambrogio Fasoli, P. G. Doyle, P. Crawley, G. Radford, L. P. D. F. Jones, B. E. Keen, P. Noll, M. Brandon, U. Gerstel, T. Winkel, R. Smith, J. F. Junger, E. Lyadina, P. Barker, F. Nave, P. J. Howarth, M. Lennholm, K. Blackler, H. McBryan, C. Grisolia, R. Sartori, and H. Summers

Subjects
Physics, Jet (fluid), Nuclear engineering, Divertor, Plasma, Condensed Matter Physics, Power (physics), Nuclear physics, Nuclear Energy and Engineering, ___, Power handling, Electron heating, Current (fluid), Scaling
Abstract

JET was extensively modified in the 1992/93 shutdown. The new pumped divertor and many new systems were brought into operation early in 1994. Operations have progressed to 4MA plasma current and, with substantial additional heating, H-mode confinement results confirm the expected scaling. The high power handling capability of the pumped divertor with sweeping is estimated at 20MW for 20s. H-mode plasmas have large Type I ELMs. With lower hybrid heating alone, 2MA full current drive has been achieved with good efficiency, with ICRF power, effective heating and direct electron heating have been demonstrated.

Published
1994
Full Text
View/download PDF

13. Plasma heating in JET

Author

A Ainsworth, H Altmann, R J Anderson, J Arbez, D Bartlett, W Bailey, K Behringer, E Bertolini, P Bertoldi, C H Best, V Bhatnagar, R J Bickerton, G Boissin, T Bonicelli, S Booth, A Boschi, G Bosia, M Botman, H Brelen, H Brinkschulte, M L Browne, M Brusati, T Budd, M Bures, P Butcher, H Buttgereit, D Cacaut, C Caldwell-Nichols, D Campbell, J Carwardine, G Celentano, C D Challis, A Cheetman, J Christiansen, C Christodoulopoulos, P Chuilon, R Claesen, J P Coad, M Cooke, J G Cordey, W Core, S Corti, A E Costley, G Cottrell, J Dean, E Deksnis, G Deschamps, K J Dietz, J Dobbing, S E Dorling, D F Duechs, G Duesing, H Duquenoy, L de Kock, A Edwards, W Engelhardt, F Erhorn, B Eriksson, H Falter, T Hellsten, J L Hemmerich, R Hemsworth, F Hendriks, R F Herzog, L Horton, J How, M Huart, A Hubbard, M Hugon, P Jones, J Kaeline, A Kaellne, A Kaye, B E Keen, M Keilhacker, G Kinahan, A Konstantellos, P Kupschus, P Lallia, J R Last, N Foden, C Froger, K Fullard, A Galetsas, A Gallacher, A Gibson, R D Gill, A Geode, A Gondhalekar, N A Gottardi, C Gowers, R Granetz, B Green, S Gregoli, F S Griph, R Haange, C J Hancock, P Harbour, R F Herog, J Kaellne, L Lauro-Taroni, E Lazzaro, R C Lobel, P Lomas, M Lorenzo-Gottardi, C Lowry, G Magyar, D Maissonneir, M Malacarne, V Marchese, P Massmann, P McMullen, M J Mead, P Meriguet, V Merlo, S Mills, P Millward, A Moissonnier, P L Mondini, P Morgan, G Murphy, M F Nave, L Nickesson, P Nielson, P Noll, S Nowak, W Obert, B Oliver, M Olsson, J O'Rourke, M G Pacco, J Paillere, L Pannacione, S Papastergiou, D Pasini, M Pescatore, J Planncoulaine, J P Poffe, R Prentice, T Raimondi, C Raymond, P H Rebut, J Removille, W Riediker, R Roberts, A Rolfe, R T Ross, G Sadler, J Saffert, N Salmon, A Sand, A Santagiustina, R Saunders, M Schmid, F C Schueller, K Selin, R Shaw, D Sigournay, R Simonini, P Smeulders, L Sonnerup, K Sonnenberg, M Stamp, C A Steed, D Stork, P E Stott, T E Stringer, D Summers, A Tanga, A Taroni, A Terrington, A Tesini, P R Thomas, E Thompson, F Tibone, R Tivery, E Usselmann, H Van der Beken, M Von Hellerman, J E Van Montfoort, T Wade, C Walker, B A Wallander, M Walravens, K Walter, M L Watkins, M Watson, D Webberley, J Wesson, J Wilks, T Winkel, C Woodward, M Wykes, D Young, L Zennelili, J Zwart, B Beaumont, D Gambier, D Moreau, J Ehrenberg, H Jaeckel, S Kissel, U Kuephnapfel, R Mueller, A Staebler, A Weller, J H Hamnen, M Evrared, M Gadeberg, K Thomsen, P Dupperrex, G Tonetti, N Lopez-Cardozo, B Tubbing, J Von Seggern, J Tagle, F Bombarda, G Bracco, R Giannella, R Carolan, M Cox, M Forrest, D Goodall, N Hawkes, P Haynes, J Hugill, K D Lawson, G McCracken, J Partridge, N Peacock, J Snipes, T Todd, H Schamel, H Summers, and S Tsuji

Subjects
Jet (fluid), Settore FIS/03, Materials science, Nuclear Energy and Engineering, Resonance, Electron temperature, Plasma, Sawtooth wave, Electron, Atomic physics, Condensed Matter Physics, Neutral beam injection, Ion
Abstract

Heating the JET plasma well above temperatures reached in the ohmic phase is the aim of the two additional heating systems planned for JET: ion cyclotron resonance heating (ICRF) and neutral beam injection (NBI). Operations with the latter started in February 1986, initially with hydrogen injection, up to a power level of 7 MW. ICRF power has been delivered to the plasma by three antennae and has reached power levels of 6 MW for 2 s. In most experiments, the frequency of the waves is adjusted to position the minority ion resonance layer close to the centre of the discharge, resulting in a centrally peaked power deposition profile. Results have also shown that the increase of the volume averaged electron temperature was much less dependent on the radial position of the ion resonance layer than were the central temperatures of both ions and electrons which can both approach 5 keV. In cases of 'on axis' heating, large increases in the sawtooth activity is observed with sawtooth periods exceeding 0.3 s. Initial results with NBI have shown a decrease of the global energy confinement time with additional power similar to the one observed with ICRF heating.

Published
1986
Full Text
View/download PDF

14. ICRF studies on JET

Author

J Jacquinot, R J Anderson, J Arbez, D Bartlett, B Beaumont, K Behringer, E Bertolini, V P Bhatnagar, T Bonicelli, G F Bosia, H W Brinkschulte, M L Browne, M Brusati, M Bures, D Campbell, J P Christiansen, C O A Christodoulopoulos, P Chuilon, R Claesen, J P Coad, J G Cordey, S Corti, A Costley, G Cottrell, B Denne, K Dietz, S Ejima, S K Erents, B T Eriksson, M Evrard, K Fullard, D Gambier, R D Gill, N Gottardi, B Green, G Grosso, N C Hawkes, T Hellsten, J L Hemmerich, M Huguet, O N Jarvis, E Jones, A S Kaye, H Kimura, J de Kock, L de Kock, H Krause, P P Lallia, J Last, E Lazzaro, P J Lomas, G Magyar, M Mansfield, V Marchese, F K Mast, G M McCracken, P Mondino, P Morgan, R M Niestadt, J O'Rourke, H Piekaar, J Plancoulaine, P H Rebut, G Rhoden, G Sadler, F Sand, A Santaquistina, M S Schmid, F Schueller, S Segre, A Sibley, M F Stamp, C A Steed, P E Stott, D Summers, A Tanga, J A Tagle, P R Thomas, K Thomsen, B J D Tubbing, M Valisa, H Van der Beken, M Watkins, T J Wade, and C I Walker

Subjects
Physics, Jet (fluid), Energy, Hydrogen, Tokamak, chemistry.chemical_element, Plasma, Condensed Matter Physics, ICRH, Plasma Heating, Nuclear Energy and Engineering, chemistry, Impurity, JET, Helium-3, Quadrupole, Antenna (radio), Atomic physics, Deposition, Scaling, Confinement
Abstract

Two antennae have been installed in JET and operated to the maximum design capability of the generators. 4.5 MW, 10 MJ have been coupled to the plasma which heated up to a maximum stored energy of 3 MJ with central temperatures of T e0=5 keV and T i0=4 keV without increase of the relative impurity concentration. Degradation of energy confinement is observed according to an L mode scaling. The effect of k/sub //// shaping is discussed using a quadrupole antenna. Hydrogen and helium 3 minority heating regimes give similar results.

Published
1986
Full Text
View/download PDF

15. Carbon deposition on metallic surfaces studied by r.f. plasma discharge

Author

I. A. Stenhouse, J. P. Coad, E. W. T. Richards, and J. A. Cairns

Subjects
Multidisciplinary, Materials science, fungi, Metallurgy, Plasma, Contamination, Catalysis, Coolant, Metal, chemistry.chemical_compound, chemistry, Ionization, visual_art, visual_art.visual_art_medium, Deposition (phase transition), Carbon monoxide
Abstract

The accumulation of carbonaceous deposits on surfaces exposed to gases containing hydrocarbons or carbon monoxide is an undesirable phenomenon which can cause contamination of, for example, steel containment vessels and catalyst surfaces. It has been found1 to occur also in certain conditions on the steel fuel pins of the Advanced Gas Cooled Reactor (AGR). Although in this instance it can be prevented by controlling the coolant composition, there is a strong motivation to understand the basic mechanisms involved. We show here, principally by means of a radio-frequency (r.f.) plasma-discharge system incorporating spectrographic analysis, that the deposits are formed largely as a result of the catalytic activities of the exposed surfaces (even here in the presence of highly ionized gases) and that deposition can be prevented by suitable coatings. These findings have now been confirmed by in-reactor experiments.

Published
1980
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results